Sprue goo?

[zuludog]

My tube of filler putty is more or less finished, and I thought that instead of buying more I'd try making my own sprue goo, but I have a question -

In the past when I've used too much tube glue this has softened the surrounding plastic and taken ages to fully dry and harden
How do I prevent this if I use sprue goo, especially on wider areas and bigger gaps?

Alternately, what is the current favourite filler - Humbrol? Revell? or knifing stopper from Halfords?

 

[Tim Marlow]

I think the issue you’ve experienced with sprue goo is down to using tube glue. I would try using something like EMA or Tamiya extra thin solvents as the base. They evaporate off more quickly after application so shouldn’t cause this.
Failing that, cellulose knife stopping is probably as good as it gets if you can still find some. It was my go to for a long time. The acrylic stuff isn’t so good. Failing that, Tamiya filler is a very close substitute. It sticks well and sands to a glass smoothness. Mr Color tube stuff (can’t remember the name, probably Mr Filler) is also good. Delux Perfect plastic putty is very good, easily the best of the acrylics, and is excellent for cracks and seams because it can be easily cleaned up when still wet, but not so good for shallow dents. Does tend to go off in the tube before you’ve used it all though.
You can, of course, just stretch some sprue and glue it in the gaps. It’s all down to what you are filling I suppose.

 

[Jakko]

I normally use car body filler from a tube, bought in a hardware store. Recently I got a tube of Tamiya white putty (due to needing it at a model show, where I had forgotten to bring any) that I have been using since, and to be honest, it feels just about the same as my usual car body filler, both when applying it and when scraping, filing and sanding it after it’s dried. Except the Tamiya filler cost me €7 for 32 g while the car body filler is about €12 for 125 g …

Aside from that, I used to like Revell Plasto, but only after squeezing all the glue-like liquid from the tube The much drier putty that remains is a lot more workable than the very wet putty you get if you knead the tube to mix the glue back in.

BTW, if you’re going to use Tim’s advice of using Tamiya extra thin to dissolve sprue, it’s much cheaper to get Tamiya airbrush cleaner instead — the bottle contains the exact same stuff as the TET bottle, but costs less than half per unit of volume. You can also refill your empty TET bottle with it, of course.

 

[Scratchbuilder]

As Jakko said, car body filler in the form of cellulose stopping putty. I bought a tube when they first invented the wheel and still not used it all... (not really but it seems to last forever). It has the same consistancy of 'Green Stuff' and Tamiya putty. The other product that can come in usefull is Mr Surfacer - you can get it in three grades from thick to thin and is ideal for filling in those small holes or scratches.

 

[BarryW]

I find that it is best to have several types at hand for different jobs.

Most commonly I use Mr Dissolved Putty which has a tiny pigment dissolved in a lacquer type base and is very self levelling. This is good for treating seams or for any uneven surface. The carrier medium evaporates off leaving the filler material in the bottom of any ‘indent’. Perfect for this gluey finger marks.

Mr Surfacer 500 is also useful for many actual gaps. Similar to above but thicker with larger pigment.

Vallejo Plastic Putty I use for larger gaps and specially where in awkward places.

Ammo Black CA is another useful gap filler to have on hand.

You can use all the above together but always make sure the material is fully cured, essential before you sand anyway.

Sprue goo, made with an extra thin cement has its uses where you want plastic welded into place to strengthen a join but can be a bit messy.

 

[rickoshea52]

Chopped up sprue dissolved in Humbrol liquid poly can be useful too. I’ve used it to create a rotor brake handle round nob and for a tail rotor fairin, also for filling larger gaps. As it’s home made you can make it as thick as you like.
Some other great tips her though.

 

[zuludog]

Thanks for your replies

I have Milliput, Mr Surfacer, and various bottles & tubes of glue
The presenters of the videos seem happy enough with sprue goo, and I have a bottle of Tamiya Extra Thin that's under half full, so I've started to make my own, partly out of curiosity
However I suspect that I will also buy some proper filler, probably Tamiya or Vallejo

 

[zuludog]

Well, this hasn't turned out very well

I added some chopped sprue to the bottle of Tamiya Extra Thin, the amount based on several YT videos ...... shook it regularly for about half a day and left it overnight
All that's happened is the sprue has clagged together on the bottom of the bottle to form a big lump and the glue is still very liquid, just coloured
It was interesting and worth trying, but I'll buy some proper filler soon

 

[Andy T]

Sounds like it needs a good stir, then if it's still too liquid add more sprue.

It took me quite a while to get a consistency I was happy with. Remember the smaller you chop the sprue, the quicker it'll dissolve. Shaving it like you were sharpening a pencil gets nice fine pieces.

 

[zuludog]

There's no convenient way to stir inside the bottle, so I'll just use it up as a slightly thicker liquid glue, and buy some tube putty

 

[Flip]

The type of filler really depends on the particular needs but one additional one I have used has proved to be quite handy (picked up in a mag, I think):

Make up a mixture of medium viscosity CA glue and pure talcum powder (not the cheap smelly stuff, but proper French Talcum). It goes grey when mixed and can be smoothed into a gap pretty easily. Try to get it as smooth as possible during application as it will cure rock-hard. Once cured, it can be filed/sanded as normal and , because it has the talc in it, can be filed/polished to a very smooth finish.

 

[zuludog]

Hmmmm .....

When I started making kits in the 1960s I made my own filler from clear dope and talcum powder, as recommended by Alan Hall in the Airfix magazine