Puttying - gaps keep appearing

Tools, Techniques, and Reference Materials Techniques
1

Putty - I can never seem to get it right.

I was hoping someone could enlighten me on my horrible techniques.

I’ve tried Tamiya putty (tube type, semi-liquid), and Millliput (two-part clay-like epoxy putty).

The problem is - no matter what I do, gaps always seem to appear between the model and the putty.

If I plug the seam with putty, wait for it to dry, then sand… The putty “flakes” off when sanding. I think this is due to the putty not “sticking” to the plastic/resin.

If I wipe the putty with nail polish remover (Acetone), the putty also comes off the model, leaving a slight depression and a visible seam line.

If I don’t wipe so much so that it leaves a depression, leaving a little putty slightly above the model surface, there is still a seam line visible where the putty joins the model surface. What to do?

Everywhere I’ve read people don’t seem to have these problems. I have given up on putty, but my next model absolutely needs putty to fill in the gaps. (The model is non-plastic. It’s some kind of ceramic/porcelain cast model. It’s a very light grey, almost white; very heavy and brittle. Is that resin?)

I’ve been trying and experimenting but I’m getting awfully frustrated. Is there a secret, or am I just doing it wrong?

I was wondering also, if there was some kind of glue that can be used to fill huge gaps. Something sticky, can be squeezed from a tube, extremely viscous (like goo), dries hard for sanding, drilling… You get the idea? Is there such a glue around?

Superglue is just too thin/watery to be used to fill gaps…

2

First, make sure your plastic is clean of mold release. Wash it rhoroughly before trying to putty it. The putty won’t stick if there is oil or grease on the surface. I usually clean parts with alcohol before puttying or painting.

Testors putty is for styrene and probably won’t work on resin (haven’t tried that!) or any kind of metallic medium. The solvents in the putty just won’t dissolve the base enough to let it stick. I would think that Milliput would have worked since that is epoxy based. I’ve had pretty good luck with Squadron putty on styrene and resin parts.

Two-part epoxy in the tubes can be used to fill large areas, but that’s basically what Milliput is, I think. It is viscous and when dry can be sanded, drilled, even threaded, but you’ll need some sort of backing for it or it will just run out of the joint. I don’t use epoxy on plastic models but for other chores I have occasionally mixed 5-minute 2-part epoxy and let it sit for a few minutes until it gets really thick. It tends to stay in place a little better that way.

I frequently use Zap-A-Gap (gap-filling Zap) for small gaps on models. It is cyanoacrylate but is thick enough to stay put in a gap. It can also be sanded once dry.

3

There are alternatives for filling seams. Milliput is not one of them. It doesn’t stick to plastic very well. I use it to backfill voids that I might sand into (two part resin fills better but takes a while to dry and if you get the proportions wrong, may get too hot or never dry) and make shapes to carve and sand parts out of. Super glue has to be used to attach it.

I have no experience with Tamiya putty, but yours doesn’t sound very good. I use a lacquer based putty that’s for automotive body work finishing; it’s readily available, spreads and sticks okay (don’t put too much on at once, it will “melt” plastic), drys reasonably fast without much shrinking, and sands easily. Other people swear by super glue - there are various techniques to make it less hard when dry like mixing it with talcum power or putting an accelerator on it after it is in place. You probably ought to start with a relatively thick super glue; get it sanded as soon as it dries to be sure that it doesn’t get too hard.

Seam lines and very small pits in the filler can be eliminated with enamel paint or white-out and fine sandpaper. This won’t work for seam lines that occur because the parts aren’t glued together.

Plastic is one thing. Resin is another, which is probably what your next model is from the description. In both cases you want to minimize the gaps by sanding the mating surfaces. With resin, thick and/or thickened (talcum powder) super glue is probably the best answer.

4

For styrene, I have the best luck with Squadron White Putty. But I use Zap-A-Gap CA+ for most filling. For resin, conventional model putties won’t work. You will have to a CA or epoxy.

5

I agree with Rick.

Put some CA glue on it and as soon as it cures sand it before it becomes too hard.

Mike

6

Wow, thanks guys!

I think I’ll try the two part 5 minute epoxy tube glue stuff. A big problem with this model is there are huge seams in unsandable areas - it’s a human figurine, not an airplane . I absolutely must be able to clear up the excess when it is still wet - if there’s too much when it’s dry I’m doomed.

I’d really like to try the Zap-a-Gap, but I can’t seem to find it in my country.

7

Your can get that 5 min epoxy for under $2.00 at wal-mart in the paint section.
Just my [2c] That’s where I got mine and it beats all the other prices I’ve seen for it by a long shot. [8D]
kelley G in tha hizzouse [8][:-,]
Cheers!!!

8

Zap-a-Gap is super glue. There are different thickness (viscosity) super glue. The gap filling kind are thicker. You can also put accelerator on the super glue to make it dry faster. Just make sure you start sanding before it has hardened completely.

By the way, what country are you in?

9

Wow! I tried the epoxy glue, and it works like a charm!

Sticks very well, dries hard. Sands well, etc…

Best of all, if sanded properly, there are NO gaps, and NO seams!

I haven’t gotten to putting primer for the final check yet. Will update you guys on the progress.

So far though, it looks great!

10

Epoxy is great stuff if you can keep it from sagging and running away from where you wanted it. I’ve used it for everything in the world. I used to build a lot of electronic stuff, and I’ve used it to hold all kinds of high-stress things together. I even drilled and tapped it for a bolt once.

It does get hard though. On styrene stuff that can make it hard to sand because the plsatic around it will go away before the epoxy does.

11

So can anyone describe the difinative difference between the Squadron white and green putties? Is there more to it than the color - such as one being a finer grain etc??

Bri~

12

The biggest difference I’ve noticed in White VS Green, is that the Green is thick, and harder for me to spread out evenly, and the white is a bit more “flexible”. Beyond that, I haven’t the clue!!!

13

The white has a finer grain to it I believe. It also dries faster than the green.

Mike

14

Personally I try and fill the gap as much as possible with some styrene, sanded or scraped down to fit in the gap, then glue that in.
After that, Tamiya putty to fix any voids.

15

I’ve switched from Squadron Green to Bondo spot putty. Behaves similarly and is a lot cheaper.