Enamel Paints on resin part

oggy4u · Post by **oggy4u** » Sat Oct 18, 2008 8:44 am

Hi everyone,
Here is my problem. I am building a PM Yak-15 in an acrobatic red colour scheme. The model is plastic but I replaced the the tail fin with a resin copy from an other model . So, I have read you cannot use enamels on resin.
Do I apply MR. Surfacer first?
Can I apply a thin layer of acrylic paint first? Then add the enamel paint!

Mixed media models are common these days so hopefully someone has the answer.

Thanks, Alan

Kylwell · Post by **Kylwell** » Sat Oct 18, 2008 10:42 am

If you've got Mr. Surfacer (or even better Mr. Resin Primer) go with that first, then paint with acrylics (enamels & lacquers don't get a long). Make sure the resin is clean, clean, clean of mold release & oils.

Does somebody out there have a list of paint compatibilities? What can go over what, and what shouldn't go over what?

kenlilly106 · Post by **kenlilly106** » Sat Oct 18, 2008 10:49 am

Enamels over bare resin is usually ok, acrylics over bare resin is a bad idea, the solvents in acrylics are normally not 'hot' enough to bond to the resin.

I'd prime it with Mr.Surfacer first, let it cure overnight, then apply the enamel or acrylic color of your choice.

The application rule is:
Lacquer then enamels then acrylics. Always go in this order and not the other way.

Ken

Kylwell · Post by **Kylwell** » Sat Oct 18, 2008 10:57 am

Ah, I had to check. Yes, enamel over lacquer is ok, but lacquer over enamel is bad. Acrylic over lacquer is fine, I do that all the time.

Mr. Badwrench · Post by **Mr. Badwrench** » Tue Oct 21, 2008 6:07 am

I've had endless trouble putting enamel over lacquer- namely, Model Master enamels over Mr. Surfacer lacquer primer. Once I put a barrier coat of Future over the primer, the problems went away. So while this seems to contradict the rules, (Enamel over acrylic over lacquer), literally years of problems vanished overnight.

kenlilly106 · Post by **kenlilly106** » Tue Oct 21, 2008 6:43 pm

Hmmm, Mr. Surfacer is basically automotive primer repackaged, and I use auto primers on a regular basis over resin, styrene, metal, epoxy and CA and I haven't had any compatibility problems, once cured the primer accepts any paints I've shot onto it.

What was your problem with the enamels and Mr. Surfacer?

Ken

Richard Baker · Post by **Richard Baker** » Tue Oct 21, 2008 7:40 pm

MODs-
How about making this thread a sticky?

.

oggy4u · Post by **oggy4u** » Wed Oct 22, 2008 10:19 am

Thanks for your input guys. I thought I could put acrylics only on resin. \this has saved me a lot of headaches. I think it is vinyl models that will accept acrylics only. It would be great to have a list of model paints like enamel, acrylic etc. and the kinds of materials they can or cannot be used with as the case may be.
Thanks, again. Alan

Mr. Badwrench · Post by **Mr. Badwrench** » Thu Oct 23, 2008 5:07 am

kenlilly106 wrote:Hmmm, Mr. Surfacer is basically automotive primer repackaged, and I use auto primers on a regular basis over resin, styrene, metal, epoxy and CA and I haven't had any compatibility problems, once cured the primer accepts any paints I've shot onto it.

What was your problem with the enamels and Mr. Surfacer?

Ken

MM enamels won't stick to it. Low tack Tamiya tape peels the stuff up. So does Parafilm-M. I can even flake it off with my fingernail. I thought perhaps the surface finish Mr. Surfacer provides was maybe too smooth, giving the enamel too little to bite into. But even roughing up the surface with 600 grit paper only helped a little. Now for the record, I usually let each coat cure for about a week. I don't do this on purpose, I just don't have all that much time to devote to painting. (I'm wasting my free time here instead...)

So I read, (on a decal instruction sheet, of all places), that putting enamels over lacquers is asking for trouble. I figured what the heck, I've got plenty of trouble, and it all started when I switched to Mr. Surfacer primer. So I tried airbrushing a barrier coat of Future over the primer. Lo and behold, the enamels stuck to the Future just fine.

I believe that when practicing any sort of skill, it is best to understand the theory first. But I am not at all averse to experimenting. Especially when there are two or more contradictory theories. This experiment seems to confirm the theory that enamels do not go over lacquers.

kenlilly106 · Post by **kenlilly106** » Sat Oct 25, 2008 11:21 am

When the MM enamels came up, was it in a few spots or all over?

What thinner did you use?

Ken

Mr. Badwrench · Post by **Mr. Badwrench** » Sat Oct 25, 2008 10:27 pm

It peeled up in spots at first, but I could get it to come off completely without much trouble. I used several different kinds of thinner, because at first I thought that was the problem, I was using cheap thinner. But I also used MM thinner, lacquer thinner, and Mr. Color leveling thinner. (BTW- the first time I used Mr. Color thinner with MM enamels was by accident. But it works really well! Better than anything else I've tried. I'm surprised.) Anyway, the results were pretty much the same. Obviously the MM thinner works better than the hardware store paint thinner, it flows thru the airbrush better and lays down more smoothly. But as far as adhesion goes, it was all crappy.

kenlilly106 · Post by **kenlilly106** » Sun Oct 26, 2008 9:09 am

At first I thought the adhesion problem was due to using a 'cooler' thinner like mineral spirits that would not melt into the primer, but would sit on top of it.

Lacquer thinner or Mr. Color would be hot enough to stick unless the paint went on in very dry coats, which I could see if the problem was in random spots where maybe the paint went on drier than in other places, but not all over.

I use the combination of auto lacquer primer and MM enamels cut w/lacquer thinner on a regular basis and I haven't had the adhesion problems you've noted.

I could see it being contamination problem where something leached through the Mr. Surfacer, but that should have happened only with one kit.

I'm really stumped on this one.

Ken

DX-SFX · Post by **DX-SFX** » Mon Oct 27, 2008 8:57 am

So I read, (on a decal instruction sheet, of all places), that putting enamels over lacquers is asking for trouble.

No, that's OK. Lacquers over enamels is bad.

As a rule of thumb, the paints with the most aggressive thinners go on first and should not be used to overcoat weaker paints.

Enamels should also stick to resin fine providing all trace of release agent or silicone residue has been removed. The more agressive car sprays tend to work better because the thinners has a greater tendency to bite through any surface contaminants but enamels don't do it so well. Truly clean resin is not a problem.

Another point that confuses people is that some paints are referred to as a cellulose enamel. They are still cellulose paints not to be confused with modelling enamels which are based on drying oils and thinned with white spirit/turps.

Any paint thinned with water should go on last although Future can provide a barrier coat to certain paints higher up the ladder (but not lacquer based car paints). That's not to say you can't 'get away with it' on occasion but it's risky and not to be recommended.