Is it just me...

[Laurie]

I have just done some airbrushing for the first time since about last September—Vallejo Model Air Grey Primer. I opened the flap and unscrewed the top and using a stiff brush cleaned all the stuck primer. I was surprised at how difficult it it was to remove all of it (which is good for modelling). Having thoroughly shaken the bottle before, I shook it a second time. (It has a rattle object in it—an M4 nut). On shooting AB cleaner through my brush (a Harder and Steenbeck CR Plus, 0.4 mm) the flow fell to half during spraying. On cleaning it, I pushed as usual an interdental brush wet with cleaner into the nozzle and a worm of quite stiff primer came out. The AB had been thoroughly cleaned last time—cup cleaned, body brushed inside with cleaner (the tiny bottle brush being inspected in a bright light against a dark background and under a magnifying lens to detect hairs before every use of it), nozzle cleaned and inspected under a magnifying lens against a bright light, put into an ultrasonic cleaner, re-assembled in clean conditions.
Despite this rigorous cleaning every time, I get blockages quite often (say every 5th session), many showing evidence that thick paint was the culprit. Any paint that had hardened blow the neck of the bottle (which perhaps I did not detect) would probably have formed a flake (like I found on the cap when cleaning) rather than produced a worm which is what I found.


How often to you others get blockages? What causes them? Are they something that we must accept?

Blockages well not at all unless I have been careless with cleaning the airbrush or I am weathering at low pressure.


Sounds to me Steve as if the paint has not been agitated enough. If you are getting a worm the paint has not been mixed well enough. I have 5 different colours of primer and just checked and they are all free of pint around the lid. Just wondered if in not stirring well the thinners and dryers have been used out of proportion to the remainder of the paint leaving the unused paint thickish.


Laurie

 

[Stevekir]

Sounds to me Steve as if the paint has not been agitated enough. If you are getting a worm the paint has not been mixed well enough.

I think that is the basic problem.

Just wondered if in not stirring well the thinners and dryers have been used out of proportion to the remainder of the paint leaving the unused paint thickish.

Yes, I can see that. It assumes that the thinners and dryers sit on top of the rest of the paint in the bottle. But I do shake really hard, and the nut in the bottle should surely mix things up. I will have to shake even harder in future. (Total shoulder replacements are increasingly successful these days!)

 

[Laurie]

I think that is the basic problem.
Yes, I can see that. It assumes that the thinners and dryers sit on top of the rest of the paint in the bottle. But I do shake really hard, and the nut in the bottle should surely mix things up. I will have to shake even harder in future. (Total shoulder replacements are increasingly successful these days!)

Steve I hold the bottle up to the light inverted. You can then see if there are dregs in the bottom. If there are I flip the top off and stir the bottom.


Laurie

 

[Stevekir]

Steve I hold the bottle up to the light inverted. You can then see if there are dregs in the bottom. If there are I flip the top off and stir the bottom.
Laurie

Yes, I do that but it works for me only for varnish. For others I can never see clear dregs. I think I will have to stir every bottle with a rod for a while and see if that makes a difference.

 

[Stevekir]

More very frustrating woes. I had another go this afternoon. Vallejo Model Air Grey Primer was sprayed successfully this time although yesterday the spray fell to about half its usual flow after a few seconds and there was a worm of stiff paint that came out of the nozzle. It seemed to have the usual thickness when poured. AB flushed out thoroughly with Vallejo AB Cleaner. After very vigorous shaking and having cleaned the spout, when pouring Vallejo Model Air "Dark Sea Grey" into the cup I noticed (too late!) that it was unusually thick. Sure enough, it blocked immediately. I cleaned the AB. (When I say "cleaned" I mean Spring Clean. Every time: remove needle, nozzle cap, needle and cup; use an interdental brush on the nozzle; pointed cotton bud on the cap; soak both in Vallejo Airbrush Cleaner; use one of those little bottle brushes soaked in cleaner up the passage from the end to the middle of the AB, several times; clean the cup; use the interdental brush again on the nozzle and check through a mag. glass while rotating it to check for anything there. What more can I do?


I then thinned the Dark Sea Grey with Vallejo Thinner to about its normal consistency as when bought fresh. Sprayed again. Almost immediate blockage. Worm again.


Shot through some "Muc-Off", "Fast Action Bike Cleaner" which I once read was good. Cleaned the AB thoroughly again, thinned some more (to a very liquid consistency), another blockage but no worm.


AB cleaner goes through the AB perfectly after cleaning.


The last time I used the AB for Acrylic was last June. It was cleaned as above with the addition of a session in the Ultrasound cleaner.


The Primer and the Dark Sea Grey were bought in March 2013 and were much used from then until Last June—15 months.


Using logic, could it be that Vallejo Acrylic Paint goes off in the bottle after a time and has to be thrown away? Does anyone else have to do that?





If not, what is going on please?

 

[Laurie]

could it be that Vallejo Acrylic Paint goes off in the bottle after a time and has to be thrown away? Does anyone else have to do that?

Vallejo say some is 10 years old and still going. From memory they say at least five years. Where do you store your paint Steve. Just not had any problems like you have.


It could be, speculating, that the nozzle was not clean or half clogged. What happens if the thinners can go thro with some paint but then the paint clogs up and courses the worm ie slightly clogges nozzle and a .35 nozzle becomes a .18.


A nother is a stray piece dryed paint, only needs a minute piece, of paint from the cup when cleaning lodges near the nozzle and then is puched into the nozzle when you load the paint.


If the cap has not been tightened up then the thinners/dryers will evaporate.


Have you tried squirting a bit of paint into a saucer and see if it looks normal.


Laurie

 

[Stevekir]

To try and defeat the Carpet Monster when handling small parts, and especially when peering through a recently cleaned airbrush nozzle (costs money to replace), I sit up very close to the edge of the work table and lean forward. Sometimes a small part, when held by tweezers which looses its grip, will jump like a cricket and land far away and be lost. Also, this can happen when cutting small parts off the sprue. The snapping shut of the cutter's blades can give it the propulsion of a Saturn rocket, so keep hold of it. I visited the Jewellery museum in Birmingham. To save bits of gold the workers had a big leather pouch fixed to the front edge of the bench and in some way kept close to their stomachs like part of an apron. We don't need to go that far! Also, when detaching several small parts from the sprue, put them in a closed container until used, not strewn on the table. And if small parts on a sprue seem loose, stick them with sellotape or something or they will loosen and disappear. Once a part has been removed from the sprue it will loose its part number which can cause difficulties if there are two or more similar parts (left and right handed for example).


It's a wonder any of us make it to the end!

 

[Laurie]

when detaching several small parts from the sprue

On small parts on the sprue before cutting I put a piece of tape across. Also for working on small pieces which may disappear into the ether I put a sticky stick on an end before holding with tweezers.


For left right handed bits I have a collection of small plastic boxes. Bit of tape on top left hand box right hand box. For pieces which have disappeared 3 pieces of wide tape sticky up across the backs of the hand is very successful. Failing that. muslin on the end of the vacuum cleaner brush is a winner.


Laurie

 

[Stevekir]

To try and defeat the Carpet Monster when....

I think I posted this in the wrong thread. I aimed at a newcomer somewhere else, just starting modelling.

 

[Stevekir]

I've ground to a halt. I simply cannot go for more than a few seconds before it blocks. I suspected the paint (Laurie: I always screw the top on hard). Perhaps lumps, so (as Laurie suggested), I took a Vallejo Model Air paint bottle (not one mentioned earlier) and poured the contents slowly into a small glass jar, watching the stream as it went in for any lumps. None. It looked at normal consistency: no thicker than normal. I cleaned the Vallejo bottle, its spout and cap incredibly well, almost surgically clean, with a brush and washing up liquid. Not an atom of flecked paint remained. Poured the paint back again looking for lumps. None. Repeated exactly for another bottle. (It also was at normal thickness). Same result (although while washing its bottle before returning its paint I noticed a small patch of paint still adhering to the inside. Not a flake, just some paint very slightly stiffer, which unlike the rest (now washed away) allowed it to remain on the bottle wall (until I brushed it away).


Airbrushed one of the paints at 20 PSI. Blockage in 2 seconds. Cleaned the AB again as thoroughly as described in my earlier post, this time also in an Ultra-sonic cleaner. The other paint in. Blockage in 2 seconds. Cleaned the AB again, also ultrasonically...


As the paint was now free of suspicion I had a minute inspection of the AB. Needle not bent. Nozzle not dented. But I noticed a small amount of crud adhering strongly to the outside of the nozzle, the main cylindrical part, not the conical nozzle part itself. Removed completely. This is where the air, not paint, flows, outside the nozzle, (I think, as the paint goes through the inside), but crud is crud and must be removed.


Sprayed one of the paints poured as above. Blocked in seconds. (I noticed a worm, a very soft worm, came out of the nozzle when I pushed the needle into it. I can't imagine where it came from. I would expect that normally all the paint would remain liquid.) Cleaned the AB, also ultrasonically. Tried the other bottle, having thinned it with Vallejo thinner, about 15%. Blocked in about 6 seconds.


At all times, Vallejo Airbrush Cleaner sprays perfectly and for a long time. Harder & Steenbeck Cr2 Plus, 0.4 mm needle. I have been able to spray Vallejo for 18 months or more very successfully. It seems that not using it for 5 months affected it.


So, unless anyone on this forum has any more suggestions (and many thanks for the help so far), and if I haven't died of exhaustion, I will send it to Everything Airbrush where I bought it 22 months ago (they have been helpful in the past). @&^$£*+;~~±|

 

[Laurie]

I've ground to a halt. |

I feel for you Steve. Matter of interest have you a leak some where. About every year they say, or some one did, replace the seals.


With a .4 needle/nozzle there should not been any problems with this airbrush which is very reliable as I know from experience.


Laurie

 

[Stevekir]

I sent my latest post to Everything Airbrush at past midnight last night and got the following reply at 08:50 this morning. Good service or what! Problem analysis and options given. I will either buy the Nozzle Cleaning Kit and Brushes(£15.54 including VAT) or a new nozzle (£13.76). Will need to think about that. What do people think?


I will report the result. If such blockages are likely in the future, the kit might be best. I will use the Drying Retarder in future.


--------------------

If your airbrush sprays cleaner or water without blocking but blocks when spraying paint then it will be residue dry paint inside the fluid chamber of the nozzle.


Cleaner or Water flows because it contains no pigments and is just fluid and can travel through the smallest areas. Model Air and any other acrylic paints have plastic paint pigments and the water based part of the paint is just a delivery system to transfer the pigments to the surface. Dried paint inside the nozzle restricts the room where paint would flow around the needle and out through the nozzle. As the pigment struggles to squeeze through the nozzle they start to block.


The Very Soft Worm that came out of the nozzle is semi cured paint. Acrylic paints are fairly quick curing and this is more so when they are sprayed through an airbrush. The air pressure semi-cures the paint while spraying resulting in paint pigments drying on the tip of the needle and inside the nozzle (known as tip dry). Unfortunately if the paint is completely cured inside the nozzle then ultrasonic cleaning won't remove the paint unless the cleaning agent is solvent based.


When airbrushing for 10 minutes at a time you should flush the airbrush through with cleaner to prevent the build-up of tip dry. Vallejo produce an additive that slows down the drying time of the paint thus reducing tip dry called Drying Retarder

https://www.everythingairbrush.com/paints/vallejo-paints/vallejo-model-air/vallejo-drying-retarder-17-ml.html




There are only two solutions to your current problem


1. Purchase the Harder & Steenbeck Nozzle Cleaning Kit and Brushes: This contains two brushes and a nozzle reamer to remove dried paint from the nozzle. There is no guarantee that this would cure the problem depending on how blocked the nozzle is



https://www.everythingairbrush.com/nozzle-cleaning-set.html




2. Purchase a new 0.4mm nozzle -

https://www.everythingairbrush.com/airbrushes/airbrush-spares/harder-steenbeck-spares/0-4mm-nozzle-for-evolution-grafo-colani-infinity-airbrush.html




Kind Regards, Tim Murrell, Manager

For the record, I never spray for more than 10 minutes before thorough cleaning and putting the AB away. I think I will copy this message to the Tutorials and How-Tos thread.

 

[Dave W]

I've not had any problems with Vallejo air.In fact the only Vallejo product that causes me problems is the matt Varnish.I used to have one of the large bottles of their polyurethane primer and it's good stuff.Then I tried Alclad primer/microfiller and was so impressed that it's now my primer of choice.Only down side is I have to use cellulose thinners to clean the airbrush after using them.

 

[Laurie]

This contains two brushes and a nozzle reamer to remove dried paint from the nozzle.

Actually if you have a magnifier light Steve place under the magnifier large end upwards and look through. You will soon locate any residue of paint. With a .4 it is easy not so with a .2. You will see, if clean a lovely round hole.


If you use a reamer take care as you will if pressing hard wreck the nozzle. Just place in the nozzle and gently turn without any pressure and with water running over the whole nozzle.


There is not much that Tim does not know except about keeping his premises tidy.


Laurie

 

[Stevekir]

Actually if you have a magnifier light Steve place under the magnifier large end upwards and look through. You will soon locate any residue of paint. With a .4 it is easy not so with a .2. You will see, if clean a lovely round hole.
If you use a reamer take care as you will if pressing hard wreck the nozzle. Just place in the nozzle and gently turn without any pressure and with water running over the whole nozzle.


There is not much that Tim does not know except about keeping his premises tidy.


Laurie

The looking at a bright light is a good idea. I do that every time after cleaning (which is why I first thought that it was the paint, in view of the odd bits I found in the bottles. If the nozzle is held at slightly different angles to the light, sky seems best, most of the length of the inside of the nozzle can be seen. During the many inspections I did recently, the inside was always shiny bright with no tiny bits. It looks like the laying up of the AB contributed to my problem—lots of time for crud to harden. Perhaps using the reamer gently every 5th time of using the AB might be a good idea, especially when laying it up for a time. How often do you use it?

 

[John Rixon]

I admire your persitance Steve! And feel your pain, there's nothing more frustrating than equipment that inexplicably starts to not work. If it were me, at that price I'd go for a new nozzle, so I'd be confident that that was all dandy. Then try again, but my money's on the primer, I still think we expect a lot when buying liquid acrylics and expect them to stay 100% uncured for a long period of time, I have tubes of artists acrylics in my box, that are just rock solid, the cap is firmly on them, and there is no air gap in the nozzle, they just eventually set. When I started buying Vallejo air colour, I wished that they were in larger bottles, I'm not so sure now! I have one large bottle of grey (just slightly not white, more like, grrr!) and one olive primer. The grey is a pain, and I think needs thinning, the olive is beautiful and sprays perfectly every time through the 2.5 nozzle - go figure! Excellent service from everything airbrush though, good to know top service still exists.

 

[Ian M]

An often over looked cause of 'goop' is an incorrect additive.


If you are for example normally using Vallejo paints, and for some reason use a spirit or cellulose base paint or primer, you naturally use the appropriate cleaners for that. Then go back to the Vallejo...The tiniest drop of cellulose thinners, hiding in the airbrush will make the Vallejo coagulate. This also works the other way.


Mr Kir. A few things to invest in:


A set of air brush cleaning brushes. John sells them. they are basically mini bottle brushes.


A fine brush with bristles long enough to go through the nozzel. Does not need to be a luxury item. as long as the hairs are long enough and will not melt in cellulose (even if you do not use the stuff!)


A squirty bottle. The empty thinners bottles never get thrown away by me. Make a hole that you can screw the nozzle of your airbrush into. Make sure it is a tight fit. After a good clean scew the nozzle into the tip of the squirt bottle and blast cleaner through it. (make sure the nozzle does not fly out.


A last good idea. Try to have a spare nozzle 'in stock' That way if you get a bad blockage, you can swap over and carry on and bath the blocked nozzle in thinners while you work on...


Due to boredom I just gave my airbrush a "damned go clean". It was clean enough to work, in fact I had just used it to prime with some Alclad primer. It was working totally OK.


Using the brushes and squirt bottles, and cellulose thinners I gave it a strip down and scrub. You would not believe the amount of "nasties" that came out of it.


So even though you think it is clean, it might not be as clean as you think.


Oh one more tip: Never add paint directly in the airbrush and thin then stir. Always mix up in a separate container.. The small clear plastic "disposable" shot glasses are perfect for this.


Ian M

 

[John Rixon]

Too true, Ian. And it only takes a particle the size of a midge's knacker to upset the status quo!

 

[Stevekir]

I admire your persitance Steve! And feel your pain, there's nothing more frustrating than equipment that inexplicably starts to not work. If it were me, at that price I'd go for a new nozzle, so I'd be confident that that was all dandy. Then try again, but my money's on the primer, I still think we expect a lot when buying liquid acrylics and expect them to stay 100% uncured for a long period of time, I have tubes of artists acrylics in my box, that are just rock solid, the cap is firmly on them, and there is no air gap in the nozzle, they just eventually set. When I started buying Vallejo air colour, I wished that they were in larger bottles, I'm not so sure now! I have one large bottle of grey (just slightly not white, more like, grrr!) and one olive primer. The grey is a pain, and I think needs thinning, the olive is beautiful and sprays perfectly every time through the 2.5 nozzle - go figure! Excellent service from everything airbrush though, good to know top service still exists.

I am about to start a new model and following your remark I will buy a fresh supply of primer. I usually use Vallejo but I wonder whether others are more stable in the can. What about the much-praised Halfords spray can primer? If it became lumpy in the can it would just block and a quick wipe of the model would repair any blobbyness, and the can could be replaced.


What do other users of Halford primer think? Is it suitable for acrylic paint over it?


On the difference between the performance of your grey and olive primers, each probably has a different pigment whose particle size might be different after they are ground, or they might be more likely to clump together. I am no physical chemist, but clumping (flocculation) is a phenomenon in chemistry that can be a help or a hindrance, depending on the application. Inter-molecular forces and all that.

 

[Laurie]

Oh one more tip: Never add paint directly in the airbrush and thin then stir.

I do Ian and have never had a problem. First I add thinners (always having a pre squirt at anything handy before on the job in hannd) then paint then a small paintbrush to give the thinners and paint a good stir. Also do the same for paint mixes. Vallejo Air 4 of this and 6 of another etc. Saves throwing away paint as you can top up as necessary.


After cleaning with airbrush cleaner I wait until it begins to make a slushing noise as it begins to empty out of the brush then stop leaving a smidgen in the nozzle. Before starting to load paint I always put in thinner to give a bit of an "oil".


Laurie