S
Stevekir
Guest
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NOTE: This posting got screwed up (also Part 2). I hope to be able to repair it sometime.
Part 1 (of 2)
These examples have been made for OO scale (1/76) but the techniques can be used for any scale.
Study images on the Internet of natural rock faces and scenes in general, both as to shape and colour. Search for “images of sedimentary” (or sandstone or igneous) “rock cliffs” etc.
Think about the scale of your model and decide the size of rock. Don’t forget a tiny piece of graffito somewhere and, if the scale allows, a bird’s nest.
Practice techniques on practice.
If using them, see the detailed instructions on Woodland Scenics’ and Scenery Express’s Web sites for the use of their products.
To minimize handling damage, a coat of matt varnish can be applied. The easiest way to do that is by brush using varnish from a DIY shop (but avoid brush marks), or better, by a spray can of matt clear synthetic lacquer such as from Tamiya. (It’s solvent is Cellulose Thinners which are smelly.)
I have no commercial involvement with Woodland Scenics or Scenic Express. The former’s products can be got from (among others):
Walton’s Models. http://shop.waltonsmodels.co.uk/index.php?cPath=79 Choose Scenic Materials.
Hobycraft. http://www.hobbycraft.co.uk/advancedsearchresults.aspx?query=woodland-scenics
Addlestone Model Centre. http://www.addlestone-models.co.uk
Scenic Express’s address is http://www.scenicexpress.com They don’t seem to have outlets in the UK.
PVA glue can be bought much more cheaply from a builders’ merchant in larger quantities than that expensively sold for scale modelling. Polyfilla is suitable for making these models unless you want to do much carving, in which case Woodlands Scenics’ Carving Plaster is better (it is not so hard).
For US and Canadian readers, Expanded Polystyrene (EPS) is generically called Styrofoam in Canada and the USA. Cellulose Thinners is called Lacquer Thinners. PVA (Poly Vinyl Acetate, similar to Elmers glue) is a white water-soluble sticky liquid widely uses as a wood or other glue, and many other purpose (including carp fishing!).
I made the five models in Items 1 to 5. The rest came from the Internet.
1. Stratified Limestone
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Limestone is a white rock which when weathered can show a variety of brown and yellow colours. It is made mainly of calcium carbonate which was either precipitated from limey seawater or formed by the shells of very tiny creatures, and then deposited at the bottom of a sea. Geological conditions changed frequently causing different material being deposited for a usually short time, such as muddy run off from the land. These cause separation of the limestone into strata (which are horizontal at this stage, it being the bottom of a sea. These separating strata can be of various thickness but are usually thin.. Over millions of years it was then compressed by later deposits (either more limestone or other material) and turned by chemical action and pressure etc. into rock. Finally it was pushed up by earth movements to the surface. This pushing often caused the limestone to tilt. The pushing also caused bending which resulted in the faults often seen at right angles to the strata. Limestone can be quite soft, or hard enough for building. The main driver of weathering is rainwater which is slightly acidic. Erosion, insertion of roots and freeze-thaw etc. all cause chunks to fall off, and surface effects such as algae, pitting, coloured minerals etc. add to the typically varied appearance of a limestone face. There is also chalk (White Cliffs of Dover) which is sufficiently soft to be readily eroded and therefore kept white
This example shows a cliff of weathered stratified limestone. The bottom stratum is much thicker. On reflection, the upper strata look a bit too perfect—they need roughing up and. The model is 9 inches (22cm) long (equivalent to 57 feet/17m in 1/76 scale)
a) Make a slab of Polyfilla about ½ inch thick. Make sure that the edges are that thickness (to avoid breakage). Make its surface fairly smooth but any large variations in thickness or folds and other surface features will help realism. It will become hard within a few hours and fully set after about 18 hours in a warm room.
b) Spread Woodland Scenics Carving Plaster C1198 a minimum of ¼ inch thick. Also make its surface fairly smooth but any variations in thickness or folds and other surface features will help realism. It will be set in about 18 hours in a warm room. (Carving Plaster is like Polyfilla but less hard and therefore easier to carve.)
d) Make your own tools, or use Woodland Scenics Easy Rock Carving Tools C1186. These consist of a double-ended chisel and pick for making the straight horizontal lines between the strata (using a ruler). Make sure that the strata line have rectangular bottoms. Rounded bottoms make it clear that a tool has been used. Use the excellent Strata Tool to cut the slightly wavy cracks running parallel with the strata. Preserve any surface features on the plaster that will improve naturalness. Use the pick again to cut the vertical cracks which in Nature will have been formed by bending deep within the Earth. Make them also with rectangular bottoms and go through the full height of each stratum.
e) Use the chisel end to remove plaster here and there to represent local failure, chips etc. Encourage breakages to make their sides and bottoms rough.
f) Paint the surface. Woodland Scenics sell several water-based earth pigments in liquid form which will need to be heavily diluted to prevent harsh colours (especially the black) and allow several coats as the colour is built up to your liking. Add the pigment using a big brush and slop it on with lots of liquid so that it runs down and into cracks and other indentations. Practice on a practice piece helps.
g) The brush I use is this one:
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h) See the Woodland Scenics movies listed in Item 5. The final application is an overall grey-ish wash to tie everything together visually (as used on many models). They advise diluting the final black 1:16 with water (the others are 1:8) but I found that was too dark for limestone. Try 1:24 or 1:30. The usual grass and shrubby etc. effects can be added.
i) The rock face needs to be embedded into the diorama or layout to look as though it has been there for millions of years and not plonked on top looking wobbly. Use plaster or scenic stuff like grass.
j) Since I made this face I discovered that the Polyfilla slab could be replaced by hardboard or similar which would be quicker and lighter. Best to varnish or paint it first with what house decorators use, to avoid water penetration which would soften it.
2. Limestone Rock Outcrop
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This depicts a heavily weathered limestone outcrop found in upland areas of Derbyshire and elsewhere. It uses the ability of polyurethane foam to produce a natural-looking surface but you might need to make several and practice to get the best shape and size. The model is set here in a simple scene as a demo. In a finished diorama it would be best if other similar outcrops were present in different sizes and probably running parallel. Make the ground surface uneven. The model is 7 inches (18 cm) long.
a) Lay a piece of plastic or other material on a work surface. Use a polyurethane foam can (about £3.50) to create on the plastic a suitably sized and shaped blob. Don’t bother to use the tube supplied—squirt straight from the plastic spout screwed on the can’s nozzle. For a small object hold the nozzle close to the plastic. Holding it further away will produce a bigger object. Release the trigger on the spray can and if there is an unwanted knob on the foam, press the nozzle inwards while the foam is still soft, but try to avoid manipulating the surface or it will look unreal. Any blob can be cut off and sanded and although its surface texture will be slightly different, paint will disguise it. The foam is incredibly sticky so avoid touching it and keep the cat away. It produces no smell and its surface hardens in about an hour, curing fully in about 5 hours in a warm place. However, the part of the base where it lies on the plastic takes longer, so turn it over to let it fully cure.
b) Clean the plastic spout and the inside of the can’s nozzle very thoroughly within a few minutes with Cellulose Thinners, using a rod such as from a wire coat hanger. Once the polyurethane sets it cannot be removed and the rest of the can will be unusable.
c) Place the model on a flat surface and note that the sides probably curve in at the bottom. These need to be removed or the rock will look unnaturally plonked on the surface rather than “growing out of it”. This is surprisingly important for realism. Therefore (perhaps with a carving knife), cut about ¼ to ½ inch of the base over its whole area (which will of course reduce the height of the model a little).
d) Paint the surface with matt white paint. I used Vallejo Model Color. When dry, and as described in Items 1 and 6, add generous runny blobs of water-based pigment from Woodland Scenics or elsewhere—Yellow Ochre and Burnt Umber. Before they have dried wash over the whole surface with Black (I used Flory Models’ Dark Dirt Weathering Wash FMW002, or Black from Woodland Scenics, both diluted, very much so in the case of the second. A black wash binds the colouring together visually and dulls any strongly coloured parts. On reflection, this model does not seem to be deeply enough embedded in the ground.
3. Hard Fractured Rock
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This rock uses the well-known method of crumpled aluminium foil.
These multifaceted rock faces come mainly from very hard igneous (formed after melting) rocks and sometimes have been shattered within the Earth, or have been shattered by explosives when making a road, or have been attacked by freeze-thaw weathering when exposed at the surface. Examples are diorite, dolerite and granite. Sandstone can also be hard but is usually a medium brown colour and often less sharply shattered. Very hard rock blasted by explosives will have very large angled facets often several feet in size in Nature whereas other less hard will have facets of only 3 inches or so. Except for granite (light colour) these rocks are usually fairly dark in colour and sometimes uniformly grey or grey with some dark reddish or even bluish or greenish colours here and there. If made of sandstone they can be browner. The model is 7 1/2 inches (19cm) wide.
a) Get a piece of new clean kitchen foil about 1 ½ times as wide and 1 ½ times as long as your rock face, for trimming (or more if you want to practice). If you just crumple it into a ball and open up you will get lots of angular faces but not much variation. Variation is essential in nature. Therefore, instead, place one hand under one side of the foil and one above. Press both sets of fingers gently together and wiggle them in a variety of ways. Work your way to the other end. This can give a variety of shapes. To get a greater variety of size of crinkles, repeat in several places but keep your fingers closer together to create patches of smaller crinkles. Experiment.
b) Lay it carefully on newspaper in a safe place face down (choose which face is best). This can be done indoors: the foam has very little smell. Make it as flat as possible without damaging the crinkles (the edges of the sheet of foil tend to curl up a little). Holding the polyurethane foam can more or less upright and quite near the foil, add the foam. It will expand during the following 10 seconds or so. Practicing on waste material will help to judge how much to apply and the distance between the nozzle and the foil. Refer to the instructions for model 2: Limestone Rock Outcrop. Don’t touch the foam because it will stick to your fingers. It stiffens in about 1 minute and sets solid in about 8 hours at room temperature.
c) See model 2 for cleaning the nozzle.
4. Cellulose Thinners and Polystyrene Foam (EPS)
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This material in the UK is officially called Expanded Polystyrene Foam (EPS) and is used in packaging. Large pieces can be found in the waste areas of firms selling domestic machinery such as washing machines or TV sets, and it is sold in some craft shops. It is very light in weight. Cellulose Thinnersdissolve polystyrene foam. You might like to experiment with dripping it on to a scrap piece of polystyrene slab to make natural-looking surfaces. But do it in a well-ventilated area such as a garage or outside.
a) Get a slab of Polystyrene not less than about 2 inches (50 mm) thick to prevent the thinners eating right through if you are over-enthusiastic. You can stick two slabs together with PVA glue but do this around the edges (in a thin line) - the thinners will not dissolve PVA. Once the Thinners has eaten through to the under slab it will join the two together.
b) Preferably using a small (probably polythene) pipette sold on the Internet, or an eye-dropper, drip very small amounts of thinners on the polystyrene, as small drops as you can. Practice first on scrap—it eats the foam quite quickly. Hold the polystyrene surface vertical with the top of your cliff uppermost. This will cause the thinners to drip down over the lower part of the surface rather than settling in pools and eating its way through to the back. By putting the drops close together the whole surface can be eaten away and forms the distorted surface shown above with no sign of the original surface. (You could experiment with lightly brushing the thinners on.) This model could represent that type of limestone which has been heavily dissolved by acidic rainwater which has run off a peat moor. It would be very difficult indeed to manually carve such a surface from plaster etc. to make it look natural. A cave could be made at the bottom, with a small stream coming out. The model is 5 inches (13 cm) long.
Here is a variation of this method which has plaster added.
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c) If the drops of Cellulose Thinners have not been close to each other you might end up with several sharp-edged pillars of uneaten plastic standing out from a lower, dissolved surface. These pillars need to be rubbed off because they would not look natural. You could then make the surface more gently undulating but rough by brushing with very wet plaster. The picture immediately above shows this and could be coloured to represent other rock types besides limestone. Again, it would need a lot of hand carving and artistic talent to achieve this type of surface. (The tree-line has been superimposed graphically for this tutorial.) The model is 15 inches (39 cm) long.
d) A different way to get a result similar to the picture above, is to make a slab of Polyfilla. When it is hard break it into a large number of small angular chips. For 1/76 scale, remember that 1 and 5 mm equal 7.6 and 38 cm respectively at full size, so you need to keep within this range. Mix them with wet plaster and apply to a support in the form of a slab of Polyfilla or other plaster, or of Expanded Polystyrene (EPS) eaten away with Cellulose Thinners to give the larger undulations (thereby saving some weight of plaster). The chips will form a suitably rough surface. Or you could add the chips afterwards to the surface of the wet plaster. The pieces of broken plaster can also make fallen rocks. Etc. etc. “The world is your lobster” as Morecambe and Wise used to say.
e) Then colour the rock faces as shown in the second example of this item, and in items 1, 2, 5 and 6.
5. Rock Moulding With Latex
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This method uses a latex mould of a real rock to make a plaster copy which I think looks very realistic. Ready-made moulds, and latex to make your own, can be bought (eg, from Woodland Scenics or Scenic Express or art shops). Both types of moulds can be re-used many times, and several model rocks can be cut, turned round, partly buried etc. to make it look like there are many different rocks. Here is an example of a rock made from a home-made mould. Your support (supporting the rock face) does not need to be covered in many separate rocks. This model is designed to sit on a 45 degree slope and is therefore triangular in side cross-section with its flat back surface (hidden in this view) stuck on to the sloping support. This would produce an outcrop in a sloping rock or earth face with the rest of the support being covered by a few similar model rocks or rubbly rock pieces (shattered plaster) and small stuff such as scattered sand glued on. Item 12 shows this although made by hand carving. Making the mould takes time and other methods are quicker for a large area, but a mould will produce very authentic-looking surfaces very difficult to make by other means. The model is 7 inches (18 cm) long.
a) Scenic Express offer “Wet Water”, a glycol mould release agent (these agents help to prevent the mould from sticking to an object, a rock in this case). Their movie shows it being sprayed on to the rock before the latex is applied. I did not use this product and had no problem in peeling off the latex mould.
b) Get some latex. This is a thick white liquid. It smells too much for a domestic environment in the open bottle and when on the rock for several minutes after each coat but after that it has no smell. I think the rock can be damp but clean its surface of dust etc. Brush on a coat of latex, finishing each area with dabbing strokes to increase the thickness of latex. The brush must be washed out after every coat in warm soapy water. Note that here you are making a cup-shaped mould which has the exposed rock surface as the base with a rim deep enough to hold pouring plaster without overflowing. Therefore, for this model, to make a ½ inch rim, coat a band of about ½ inch wide of the rock surfaces which are at an angle to the exposed rock surface. Get the rim as thick with latex as the rest of the mould, especially at its edge, to minimize tearing when peeled off. The photo below shows the base of the mould (exposed rock surface) facing you and part of the rim at right angles to it. Each coat will take about 3 hours or more to dry in a cool garage (a hair dryer speeds things up here), about 2 hours in a warm room, and less if placed on a hot central heating radiator. Hollows will take longer but it seems OK to put another coat over a hollow still showing some white. It becomes almost transparent when fully dry. Apply several coats, perhaps 3 for a small hand-held rock. I gave this rock 4 coats. The movie on Scenic Express’s site mentions the use of a reinforcing gauze. I did not use that for this model but it might be necessary for much bigger rocks.
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c) When fully dry peel off the mould carefully. You can judge whether more coats are needed at this stage. Starting the peel is quite easy. The latex does not stick to the rock (at least not in making this model). Rub you finger at 90 degrees over the edge until a small amount has been rolled up, then gently lift the edge and stretch the latex away from the edge of the mould as you put something like a wooden coffee stirrer gently under the latex to prize it over an inch or so from the rim. The latex is very elastic and will stand quite a lot of pulling. Having got a hold on the latex, gently pull the mould off the rock. Inspect it for holes.
d) Scenic Express has a useful movie “Making a Basic Latex Rock Mold” at:
As mentioned above, I did not find the latex sticking to the rock.
e) Brush the inside of the mould with a mould release agent (two drops of washing-up liquid in a cup of water) although I am not sure that is necessary to prevent sticking but (this is a guess) it might destroy bubbles because of the lower surface tension of the plaster close to the mould. Place the mould on a piece of plywood, chipboard, cardboard etc. (the base) on the table. If the bottom of the mould has a lump (following a depression in the rock at that point) put a small ball of wet newspaper under it to prevent the weight of the plaster flattening it. The rock being triangular in section it was necessary to prop the base at an angle so that the rim all the way round was level so that plaster would reach all of it without spilling out. The rim is quite floppy and might need support to prevent it bulging after plaster is poured. (See the next photo.)
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f) Make a pourable mix of Polyfilla and remove lumps but don’t beat it vigorously like when making a cake because that will create bubbles whose hollows are very unconvincing on a rock face. If the rim is stiff enough or well-enough supported, fill the mould up to the top, preferably in one go to prevent a “seam” line. Gently try to reduce the number of bubbles touching bottom (what will become the exposed rock surface). It might be a good idea to use a soft but coarse brush to brush the bottom of the mould. Alternatively, you could brush the mould with a thin coat of plaster. This might minimize the production of bubbles. Setting takes about 4 hours, but it will still be tender. It takes about 12 hours to strengthen fully and longer to dry out completely. (One of Woodland Scenics’ movies states that their special plaster, Hydrocal, sets more quickly.)
g) Note that the side of the base nearest the camera had been propped up to give a backward slope. This is to make the rim of the mould level, (remember that here, the mould is triangle-shaped). Also, the back left of the base has been raised to make the mould level in the left-right direction. When you judge that the plaster is strong enough (about 3 to 4 hours, peel back from the edges of the mould to reveal your rock. Check for bubble-holes on the surface and fill them.
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h) There are many holes seen above, necessary for a moon surface but not here, and I spent a relaxing half hour filling them with plaster using a cocktail stick. Pressing the filling with a finger made them disappear. If the surface on which the model is placed requires a different painting programme, the painting of the model could be done before fixing. Otherwise fix it to the support with plaster, adding plaster around the rim to make sure that the model seems to “grow out of the ground” rather than being plonked on the top.
i) Next is painting. If you want to make a colourful rock, paint as shown in Items 1, 2 and 6. As my original rock was quite plain and a dark grey, I chose to add the black wash first, (the opposite way round from the Woodland Scenics’s method) as dark grey is the dominant colour. I found that it is best with all rock painting to have a very weak wash coat and slosh it on generously. One advantage is that you need several coats and can therefore make adjustments to the depth and variation of colour. I applied three generous coats of quite dilute black wash with the big brush shown above, pressing the brush end-on to the surface (stippling) before setting each coat to dry. This gave a mottled appearance which the original rock had. Where appropriate, consider holding the rock vertically to make the dribbles flow. The slight yellow (Yellow Ochre) and orange (Burnt Umber) colouring were added using a small brush.
j) A point on adding black wash (and this applies to any colour): if you add it using a small brush it will dry pale grey, but the same black wash (same dilution) applied with the big brush described above will dry much darker because much more colour has been applied. I actually made two trial castings before I got it right . Once colour is added it is immediately absorbed by the plaster and is there for ever. As usual, a final coat of clear matt varnish should be added to fix the colour (and the plaster). Use a spray can which is easier than an airbrush.
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In this close-up, note the three shades of black/white: black on the lower surfaces where the wash pooled; medium grey on the intermediate surface; pale grey in the ridges and other higher areas, and a nearly white area on the tops. The pale grey on the ridges and white on the tops can be made more noticeable by gently rubbing with a kitchen sponge—the type with a medium-coarse surface. (This has a similar effect as dry brushing.) These differences occur in real rock of this type and ad the perception of depth, and I think it looks very realistic.
6. Thick Stratum of Heavily Weathered Limestone.
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This shows an example by Woodland Scenics of a heavily weathered rock face or outcrop which is formed from a single thick limestone stratum. Therefore, there are no separate strata to cut but lots of horizontal and some vertical cracks
a) Begin with making the support for your face or outcrop. If a face, it could be made in the form of a flat slab of Expanded Polystyrene (EPS). If it will have a top surface (as shown here), make a support curved away from the face at the top to produce a gentle slope or flat ground. This support could be made with stiff damp paper coated with PVA to strengthen it, or (easier as shown above) use Woodland Scenics Shaper Sheet C1178 which is a semi-stiff sheet which can be shaped by hand to give the basic curves, lumps and hollows and will keep its shape. Cover about ½ inch thick plaster with undulations. Slop it on. Once set and following the undulations, cover with Woodland Scenics Carving Plaster C1198 to a minimum of ¼ inch thick, (also used in Item 1. It will be set in about 18 hours in a warm room. (Carving Plaster is like Polyfilla but less hard and therefore easier to carve.) In all cases make the surface quite rough with lumps and indentations and some small overhangs
b) When the carving plaster is hard, spray it with water to make it a little softer. Use the Woodland Scenics Easy Rock Carving Tools. Use the (very effective) Strata Tool to cut the small semi-horizontal slightly wavy cracks. Press hard to make them obvious. Then use the double-ended chisel + pick for making curved cracks and to break off rough chips. There is a good movie of this below:
and the same at
http://woodlandscenics.woodlandscenics.com/show/video/RockCarving
Making a rock face and colouring it:
http://woodlandscenics.woodlandscenics.com/show/video/RealisticRocks_TipsnTechniques
c) Colour the surface with very generous blobs of highly diluted water-based pigments Yellow Ochre, Burnt Umber and Black (as an overall wash) from Woodland Scenics or elsewhere, as shown in the above movies and in item 1 above. Slop it all on generously. There is advice above in paragraph i) of Item 5. Rock Moulding With Latex.
Practice this before hand.
Continued in Part 2....
NOTE: This posting got screwed up (also Part 2). I hope to be able to repair it sometime.
Part 1 (of 2)
These examples have been made for OO scale (1/76) but the techniques can be used for any scale.
Study images on the Internet of natural rock faces and scenes in general, both as to shape and colour. Search for “images of sedimentary” (or sandstone or igneous) “rock cliffs” etc.
Think about the scale of your model and decide the size of rock. Don’t forget a tiny piece of graffito somewhere and, if the scale allows, a bird’s nest.
Practice techniques on practice.
If using them, see the detailed instructions on Woodland Scenics’ and Scenery Express’s Web sites for the use of their products.
To minimize handling damage, a coat of matt varnish can be applied. The easiest way to do that is by brush using varnish from a DIY shop (but avoid brush marks), or better, by a spray can of matt clear synthetic lacquer such as from Tamiya. (It’s solvent is Cellulose Thinners which are smelly.)
I have no commercial involvement with Woodland Scenics or Scenic Express. The former’s products can be got from (among others):
Walton’s Models. http://shop.waltonsmodels.co.uk/index.php?cPath=79 Choose Scenic Materials.
Hobycraft. http://www.hobbycraft.co.uk/advancedsearchresults.aspx?query=woodland-scenics
Addlestone Model Centre. http://www.addlestone-models.co.uk
Scenic Express’s address is http://www.scenicexpress.com They don’t seem to have outlets in the UK.
PVA glue can be bought much more cheaply from a builders’ merchant in larger quantities than that expensively sold for scale modelling. Polyfilla is suitable for making these models unless you want to do much carving, in which case Woodlands Scenics’ Carving Plaster is better (it is not so hard).
For US and Canadian readers, Expanded Polystyrene (EPS) is generically called Styrofoam in Canada and the USA. Cellulose Thinners is called Lacquer Thinners. PVA (Poly Vinyl Acetate, similar to Elmers glue) is a white water-soluble sticky liquid widely uses as a wood or other glue, and many other purpose (including carp fishing!).
I made the five models in Items 1 to 5. The rest came from the Internet.
1. Stratified Limestone
View attachment 150158
Limestone is a white rock which when weathered can show a variety of brown and yellow colours. It is made mainly of calcium carbonate which was either precipitated from limey seawater or formed by the shells of very tiny creatures, and then deposited at the bottom of a sea. Geological conditions changed frequently causing different material being deposited for a usually short time, such as muddy run off from the land. These cause separation of the limestone into strata (which are horizontal at this stage, it being the bottom of a sea. These separating strata can be of various thickness but are usually thin.. Over millions of years it was then compressed by later deposits (either more limestone or other material) and turned by chemical action and pressure etc. into rock. Finally it was pushed up by earth movements to the surface. This pushing often caused the limestone to tilt. The pushing also caused bending which resulted in the faults often seen at right angles to the strata. Limestone can be quite soft, or hard enough for building. The main driver of weathering is rainwater which is slightly acidic. Erosion, insertion of roots and freeze-thaw etc. all cause chunks to fall off, and surface effects such as algae, pitting, coloured minerals etc. add to the typically varied appearance of a limestone face. There is also chalk (White Cliffs of Dover) which is sufficiently soft to be readily eroded and therefore kept white
This example shows a cliff of weathered stratified limestone. The bottom stratum is much thicker. On reflection, the upper strata look a bit too perfect—they need roughing up and. The model is 9 inches (22cm) long (equivalent to 57 feet/17m in 1/76 scale)
a) Make a slab of Polyfilla about ½ inch thick. Make sure that the edges are that thickness (to avoid breakage). Make its surface fairly smooth but any large variations in thickness or folds and other surface features will help realism. It will become hard within a few hours and fully set after about 18 hours in a warm room.
b) Spread Woodland Scenics Carving Plaster C1198 a minimum of ¼ inch thick. Also make its surface fairly smooth but any variations in thickness or folds and other surface features will help realism. It will be set in about 18 hours in a warm room. (Carving Plaster is like Polyfilla but less hard and therefore easier to carve.)
d) Make your own tools, or use Woodland Scenics Easy Rock Carving Tools C1186. These consist of a double-ended chisel and pick for making the straight horizontal lines between the strata (using a ruler). Make sure that the strata line have rectangular bottoms. Rounded bottoms make it clear that a tool has been used. Use the excellent Strata Tool to cut the slightly wavy cracks running parallel with the strata. Preserve any surface features on the plaster that will improve naturalness. Use the pick again to cut the vertical cracks which in Nature will have been formed by bending deep within the Earth. Make them also with rectangular bottoms and go through the full height of each stratum.
e) Use the chisel end to remove plaster here and there to represent local failure, chips etc. Encourage breakages to make their sides and bottoms rough.
f) Paint the surface. Woodland Scenics sell several water-based earth pigments in liquid form which will need to be heavily diluted to prevent harsh colours (especially the black) and allow several coats as the colour is built up to your liking. Add the pigment using a big brush and slop it on with lots of liquid so that it runs down and into cracks and other indentations. Practice on a practice piece helps.
g) The brush I use is this one:
View attachment 150159
h) See the Woodland Scenics movies listed in Item 5. The final application is an overall grey-ish wash to tie everything together visually (as used on many models). They advise diluting the final black 1:16 with water (the others are 1:8) but I found that was too dark for limestone. Try 1:24 or 1:30. The usual grass and shrubby etc. effects can be added.
i) The rock face needs to be embedded into the diorama or layout to look as though it has been there for millions of years and not plonked on top looking wobbly. Use plaster or scenic stuff like grass.
j) Since I made this face I discovered that the Polyfilla slab could be replaced by hardboard or similar which would be quicker and lighter. Best to varnish or paint it first with what house decorators use, to avoid water penetration which would soften it.
2. Limestone Rock Outcrop
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This depicts a heavily weathered limestone outcrop found in upland areas of Derbyshire and elsewhere. It uses the ability of polyurethane foam to produce a natural-looking surface but you might need to make several and practice to get the best shape and size. The model is set here in a simple scene as a demo. In a finished diorama it would be best if other similar outcrops were present in different sizes and probably running parallel. Make the ground surface uneven. The model is 7 inches (18 cm) long.
a) Lay a piece of plastic or other material on a work surface. Use a polyurethane foam can (about £3.50) to create on the plastic a suitably sized and shaped blob. Don’t bother to use the tube supplied—squirt straight from the plastic spout screwed on the can’s nozzle. For a small object hold the nozzle close to the plastic. Holding it further away will produce a bigger object. Release the trigger on the spray can and if there is an unwanted knob on the foam, press the nozzle inwards while the foam is still soft, but try to avoid manipulating the surface or it will look unreal. Any blob can be cut off and sanded and although its surface texture will be slightly different, paint will disguise it. The foam is incredibly sticky so avoid touching it and keep the cat away. It produces no smell and its surface hardens in about an hour, curing fully in about 5 hours in a warm place. However, the part of the base where it lies on the plastic takes longer, so turn it over to let it fully cure.
b) Clean the plastic spout and the inside of the can’s nozzle very thoroughly within a few minutes with Cellulose Thinners, using a rod such as from a wire coat hanger. Once the polyurethane sets it cannot be removed and the rest of the can will be unusable.
c) Place the model on a flat surface and note that the sides probably curve in at the bottom. These need to be removed or the rock will look unnaturally plonked on the surface rather than “growing out of it”. This is surprisingly important for realism. Therefore (perhaps with a carving knife), cut about ¼ to ½ inch of the base over its whole area (which will of course reduce the height of the model a little).
d) Paint the surface with matt white paint. I used Vallejo Model Color. When dry, and as described in Items 1 and 6, add generous runny blobs of water-based pigment from Woodland Scenics or elsewhere—Yellow Ochre and Burnt Umber. Before they have dried wash over the whole surface with Black (I used Flory Models’ Dark Dirt Weathering Wash FMW002, or Black from Woodland Scenics, both diluted, very much so in the case of the second. A black wash binds the colouring together visually and dulls any strongly coloured parts. On reflection, this model does not seem to be deeply enough embedded in the ground.
3. Hard Fractured Rock
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This rock uses the well-known method of crumpled aluminium foil.
These multifaceted rock faces come mainly from very hard igneous (formed after melting) rocks and sometimes have been shattered within the Earth, or have been shattered by explosives when making a road, or have been attacked by freeze-thaw weathering when exposed at the surface. Examples are diorite, dolerite and granite. Sandstone can also be hard but is usually a medium brown colour and often less sharply shattered. Very hard rock blasted by explosives will have very large angled facets often several feet in size in Nature whereas other less hard will have facets of only 3 inches or so. Except for granite (light colour) these rocks are usually fairly dark in colour and sometimes uniformly grey or grey with some dark reddish or even bluish or greenish colours here and there. If made of sandstone they can be browner. The model is 7 1/2 inches (19cm) wide.
a) Get a piece of new clean kitchen foil about 1 ½ times as wide and 1 ½ times as long as your rock face, for trimming (or more if you want to practice). If you just crumple it into a ball and open up you will get lots of angular faces but not much variation. Variation is essential in nature. Therefore, instead, place one hand under one side of the foil and one above. Press both sets of fingers gently together and wiggle them in a variety of ways. Work your way to the other end. This can give a variety of shapes. To get a greater variety of size of crinkles, repeat in several places but keep your fingers closer together to create patches of smaller crinkles. Experiment.
b) Lay it carefully on newspaper in a safe place face down (choose which face is best). This can be done indoors: the foam has very little smell. Make it as flat as possible without damaging the crinkles (the edges of the sheet of foil tend to curl up a little). Holding the polyurethane foam can more or less upright and quite near the foil, add the foam. It will expand during the following 10 seconds or so. Practicing on waste material will help to judge how much to apply and the distance between the nozzle and the foil. Refer to the instructions for model 2: Limestone Rock Outcrop. Don’t touch the foam because it will stick to your fingers. It stiffens in about 1 minute and sets solid in about 8 hours at room temperature.
c) See model 2 for cleaning the nozzle.
4. Cellulose Thinners and Polystyrene Foam (EPS)
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This material in the UK is officially called Expanded Polystyrene Foam (EPS) and is used in packaging. Large pieces can be found in the waste areas of firms selling domestic machinery such as washing machines or TV sets, and it is sold in some craft shops. It is very light in weight. Cellulose Thinnersdissolve polystyrene foam. You might like to experiment with dripping it on to a scrap piece of polystyrene slab to make natural-looking surfaces. But do it in a well-ventilated area such as a garage or outside.
a) Get a slab of Polystyrene not less than about 2 inches (50 mm) thick to prevent the thinners eating right through if you are over-enthusiastic. You can stick two slabs together with PVA glue but do this around the edges (in a thin line) - the thinners will not dissolve PVA. Once the Thinners has eaten through to the under slab it will join the two together.
b) Preferably using a small (probably polythene) pipette sold on the Internet, or an eye-dropper, drip very small amounts of thinners on the polystyrene, as small drops as you can. Practice first on scrap—it eats the foam quite quickly. Hold the polystyrene surface vertical with the top of your cliff uppermost. This will cause the thinners to drip down over the lower part of the surface rather than settling in pools and eating its way through to the back. By putting the drops close together the whole surface can be eaten away and forms the distorted surface shown above with no sign of the original surface. (You could experiment with lightly brushing the thinners on.) This model could represent that type of limestone which has been heavily dissolved by acidic rainwater which has run off a peat moor. It would be very difficult indeed to manually carve such a surface from plaster etc. to make it look natural. A cave could be made at the bottom, with a small stream coming out. The model is 5 inches (13 cm) long.
Here is a variation of this method which has plaster added.
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c) If the drops of Cellulose Thinners have not been close to each other you might end up with several sharp-edged pillars of uneaten plastic standing out from a lower, dissolved surface. These pillars need to be rubbed off because they would not look natural. You could then make the surface more gently undulating but rough by brushing with very wet plaster. The picture immediately above shows this and could be coloured to represent other rock types besides limestone. Again, it would need a lot of hand carving and artistic talent to achieve this type of surface. (The tree-line has been superimposed graphically for this tutorial.) The model is 15 inches (39 cm) long.
d) A different way to get a result similar to the picture above, is to make a slab of Polyfilla. When it is hard break it into a large number of small angular chips. For 1/76 scale, remember that 1 and 5 mm equal 7.6 and 38 cm respectively at full size, so you need to keep within this range. Mix them with wet plaster and apply to a support in the form of a slab of Polyfilla or other plaster, or of Expanded Polystyrene (EPS) eaten away with Cellulose Thinners to give the larger undulations (thereby saving some weight of plaster). The chips will form a suitably rough surface. Or you could add the chips afterwards to the surface of the wet plaster. The pieces of broken plaster can also make fallen rocks. Etc. etc. “The world is your lobster” as Morecambe and Wise used to say.
e) Then colour the rock faces as shown in the second example of this item, and in items 1, 2, 5 and 6.
5. Rock Moulding With Latex
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This method uses a latex mould of a real rock to make a plaster copy which I think looks very realistic. Ready-made moulds, and latex to make your own, can be bought (eg, from Woodland Scenics or Scenic Express or art shops). Both types of moulds can be re-used many times, and several model rocks can be cut, turned round, partly buried etc. to make it look like there are many different rocks. Here is an example of a rock made from a home-made mould. Your support (supporting the rock face) does not need to be covered in many separate rocks. This model is designed to sit on a 45 degree slope and is therefore triangular in side cross-section with its flat back surface (hidden in this view) stuck on to the sloping support. This would produce an outcrop in a sloping rock or earth face with the rest of the support being covered by a few similar model rocks or rubbly rock pieces (shattered plaster) and small stuff such as scattered sand glued on. Item 12 shows this although made by hand carving. Making the mould takes time and other methods are quicker for a large area, but a mould will produce very authentic-looking surfaces very difficult to make by other means. The model is 7 inches (18 cm) long.
a) Scenic Express offer “Wet Water”, a glycol mould release agent (these agents help to prevent the mould from sticking to an object, a rock in this case). Their movie shows it being sprayed on to the rock before the latex is applied. I did not use this product and had no problem in peeling off the latex mould.
b) Get some latex. This is a thick white liquid. It smells too much for a domestic environment in the open bottle and when on the rock for several minutes after each coat but after that it has no smell. I think the rock can be damp but clean its surface of dust etc. Brush on a coat of latex, finishing each area with dabbing strokes to increase the thickness of latex. The brush must be washed out after every coat in warm soapy water. Note that here you are making a cup-shaped mould which has the exposed rock surface as the base with a rim deep enough to hold pouring plaster without overflowing. Therefore, for this model, to make a ½ inch rim, coat a band of about ½ inch wide of the rock surfaces which are at an angle to the exposed rock surface. Get the rim as thick with latex as the rest of the mould, especially at its edge, to minimize tearing when peeled off. The photo below shows the base of the mould (exposed rock surface) facing you and part of the rim at right angles to it. Each coat will take about 3 hours or more to dry in a cool garage (a hair dryer speeds things up here), about 2 hours in a warm room, and less if placed on a hot central heating radiator. Hollows will take longer but it seems OK to put another coat over a hollow still showing some white. It becomes almost transparent when fully dry. Apply several coats, perhaps 3 for a small hand-held rock. I gave this rock 4 coats. The movie on Scenic Express’s site mentions the use of a reinforcing gauze. I did not use that for this model but it might be necessary for much bigger rocks.
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c) When fully dry peel off the mould carefully. You can judge whether more coats are needed at this stage. Starting the peel is quite easy. The latex does not stick to the rock (at least not in making this model). Rub you finger at 90 degrees over the edge until a small amount has been rolled up, then gently lift the edge and stretch the latex away from the edge of the mould as you put something like a wooden coffee stirrer gently under the latex to prize it over an inch or so from the rim. The latex is very elastic and will stand quite a lot of pulling. Having got a hold on the latex, gently pull the mould off the rock. Inspect it for holes.
d) Scenic Express has a useful movie “Making a Basic Latex Rock Mold” at:
As mentioned above, I did not find the latex sticking to the rock.
e) Brush the inside of the mould with a mould release agent (two drops of washing-up liquid in a cup of water) although I am not sure that is necessary to prevent sticking but (this is a guess) it might destroy bubbles because of the lower surface tension of the plaster close to the mould. Place the mould on a piece of plywood, chipboard, cardboard etc. (the base) on the table. If the bottom of the mould has a lump (following a depression in the rock at that point) put a small ball of wet newspaper under it to prevent the weight of the plaster flattening it. The rock being triangular in section it was necessary to prop the base at an angle so that the rim all the way round was level so that plaster would reach all of it without spilling out. The rim is quite floppy and might need support to prevent it bulging after plaster is poured. (See the next photo.)
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f) Make a pourable mix of Polyfilla and remove lumps but don’t beat it vigorously like when making a cake because that will create bubbles whose hollows are very unconvincing on a rock face. If the rim is stiff enough or well-enough supported, fill the mould up to the top, preferably in one go to prevent a “seam” line. Gently try to reduce the number of bubbles touching bottom (what will become the exposed rock surface). It might be a good idea to use a soft but coarse brush to brush the bottom of the mould. Alternatively, you could brush the mould with a thin coat of plaster. This might minimize the production of bubbles. Setting takes about 4 hours, but it will still be tender. It takes about 12 hours to strengthen fully and longer to dry out completely. (One of Woodland Scenics’ movies states that their special plaster, Hydrocal, sets more quickly.)
g) Note that the side of the base nearest the camera had been propped up to give a backward slope. This is to make the rim of the mould level, (remember that here, the mould is triangle-shaped). Also, the back left of the base has been raised to make the mould level in the left-right direction. When you judge that the plaster is strong enough (about 3 to 4 hours, peel back from the edges of the mould to reveal your rock. Check for bubble-holes on the surface and fill them.
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h) There are many holes seen above, necessary for a moon surface but not here, and I spent a relaxing half hour filling them with plaster using a cocktail stick. Pressing the filling with a finger made them disappear. If the surface on which the model is placed requires a different painting programme, the painting of the model could be done before fixing. Otherwise fix it to the support with plaster, adding plaster around the rim to make sure that the model seems to “grow out of the ground” rather than being plonked on the top.
i) Next is painting. If you want to make a colourful rock, paint as shown in Items 1, 2 and 6. As my original rock was quite plain and a dark grey, I chose to add the black wash first, (the opposite way round from the Woodland Scenics’s method) as dark grey is the dominant colour. I found that it is best with all rock painting to have a very weak wash coat and slosh it on generously. One advantage is that you need several coats and can therefore make adjustments to the depth and variation of colour. I applied three generous coats of quite dilute black wash with the big brush shown above, pressing the brush end-on to the surface (stippling) before setting each coat to dry. This gave a mottled appearance which the original rock had. Where appropriate, consider holding the rock vertically to make the dribbles flow. The slight yellow (Yellow Ochre) and orange (Burnt Umber) colouring were added using a small brush.
j) A point on adding black wash (and this applies to any colour): if you add it using a small brush it will dry pale grey, but the same black wash (same dilution) applied with the big brush described above will dry much darker because much more colour has been applied. I actually made two trial castings before I got it right . Once colour is added it is immediately absorbed by the plaster and is there for ever. As usual, a final coat of clear matt varnish should be added to fix the colour (and the plaster). Use a spray can which is easier than an airbrush.
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In this close-up, note the three shades of black/white: black on the lower surfaces where the wash pooled; medium grey on the intermediate surface; pale grey in the ridges and other higher areas, and a nearly white area on the tops. The pale grey on the ridges and white on the tops can be made more noticeable by gently rubbing with a kitchen sponge—the type with a medium-coarse surface. (This has a similar effect as dry brushing.) These differences occur in real rock of this type and ad the perception of depth, and I think it looks very realistic.
6. Thick Stratum of Heavily Weathered Limestone.
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This shows an example by Woodland Scenics of a heavily weathered rock face or outcrop which is formed from a single thick limestone stratum. Therefore, there are no separate strata to cut but lots of horizontal and some vertical cracks
a) Begin with making the support for your face or outcrop. If a face, it could be made in the form of a flat slab of Expanded Polystyrene (EPS). If it will have a top surface (as shown here), make a support curved away from the face at the top to produce a gentle slope or flat ground. This support could be made with stiff damp paper coated with PVA to strengthen it, or (easier as shown above) use Woodland Scenics Shaper Sheet C1178 which is a semi-stiff sheet which can be shaped by hand to give the basic curves, lumps and hollows and will keep its shape. Cover about ½ inch thick plaster with undulations. Slop it on. Once set and following the undulations, cover with Woodland Scenics Carving Plaster C1198 to a minimum of ¼ inch thick, (also used in Item 1. It will be set in about 18 hours in a warm room. (Carving Plaster is like Polyfilla but less hard and therefore easier to carve.) In all cases make the surface quite rough with lumps and indentations and some small overhangs
b) When the carving plaster is hard, spray it with water to make it a little softer. Use the Woodland Scenics Easy Rock Carving Tools. Use the (very effective) Strata Tool to cut the small semi-horizontal slightly wavy cracks. Press hard to make them obvious. Then use the double-ended chisel + pick for making curved cracks and to break off rough chips. There is a good movie of this below:
http://woodlandscenics.woodlandscenics.com/show/video/RockCarving
Making a rock face and colouring it:
http://woodlandscenics.woodlandscenics.com/show/video/RealisticRocks_TipsnTechniques
c) Colour the surface with very generous blobs of highly diluted water-based pigments Yellow Ochre, Burnt Umber and Black (as an overall wash) from Woodland Scenics or elsewhere, as shown in the above movies and in item 1 above. Slop it all on generously. There is advice above in paragraph i) of Item 5. Rock Moulding With Latex.
Practice this before hand.
Continued in Part 2....
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