Clear coating bare plastic

[anime52k8]

I've noticed some semi-frequent talk in the toy section about applying clear coats to toys partially or competely unpainted toys to protect factory markings and small paint apps from scratches, so I decided to give it a try on a gundam model. I ended up taking the kit (which had decals and panel lining applied directly to the plastic) and coating all the armor parts with Model Masters Flat clear Lacquer. When everything was said and done, the clear coat appears to have dried completely and while it stays on well enough it's fairly easy to scratch all the way down to bare plastic.

So is this normal? I don't use Flat clear all that often on models and never over bare plastic.

I'm wondering if anyone has advice/ideas on how to get Clear paint to stick better to unpainted plastic. Is their any special prep-work I need to do to the plastic? (I cleaned the parts before applying decals and I tried to avoid getting any oil/residue on the parts before painting it)

Is it the type of paint I'm using (Model Masters paint is made by Testors and it seams to be about the same as Dullcote). Do I need to apply more coats of paint or maybe start with a gloss/semi-gloss coat before applying the flat clear coat?

any advice for the future or advice on how to improve the durability of the clear coat on the kit I've already painted. (for that kit, stripping it and starting over isn't really an option as I'd loose all the decals and I don't want to have to track down a replacement set and apply them all again, also I want to keep the matte finish so any additional paint needs to be matte.)

:edit:

It might be wroth noting that the gundam kit was given only one full coat of clear. Also, I have noticed that some of the leg armor got a heavier coat than other parts and those parts seem to be a little better, although I haven't tried scratching at them or anything to really test it.

Edited June 4, 2010 by anime52k8

[Vifam7]

Clear coat is technically just a "clear" type of paint so they will come off if you scratch hard with fingernails or use sandpaper.

That said, with regards to clear coating the bare plastic of Gundam models, one thing I can advise to make the clear coating stick better is to clean the plastic of mold release and any oils from your fingers. Mold release in particular hurts the adhesion of paint on plastic.

It's often recommended that you wash the parts with dish washing liquid before & after buildup.

Most of the time I just lightly wipe the parts down with a clean rag and some rubbing alcohol (probably not the best/recommended way).

[anime52k8]

I do my best to wash parts before painting, although in this case I didn't want to risk scrubbing off the decals. I'm beginning to think the main problem was that the layer of paint was too thin in spots. thin enough that even a very light abrasion will go all the way through the paint.

if I'm lucky a couple more coats of paint will help (fingers crossed)

[Noyhauser]

This site might be of help... If you have more questions just ask. Using future is tough, I've been experimenting with it lately because it works so much differently with slight variations in the mixture. Edited June 4, 2010 by Noyhauser

[David Hingtgen]

Most clear coats aren't a special formula or anything---they just don't have pigment. Clear gloss is the same as glossy bright red, without the red pigment. Clear flat is the same as flat black, without the black pigment. Treat clear coat paints the same as you would normal paint.

Future is one of the few exceptions, as it's not intended to be used as model paint, it just works really well for our purposes. (some people like future so much they do try to mix it with paint and use it for their color coats---works with some, not others)

[thegunny]

Most clear coats aren't a special formula or anything---they just don't have pigment.

That's a bit simplistic and not quite true.

@OP; You could try using a polyurethane based clear that is sold in art shops. It does provide a fairly scratch proof finish but you have to be careful using it as some of them can be quite thick and can clog up detail if you get too heavy handed.

I used Jo-Sonja's polyurethane matt on my Warhammer figures as I was sick of them getting chipped all the time during the heat of battle. Worked like treat, never had to touch up any chips again.

Edit: One more thing you can rub down the surface with 600 or finer (400 if you are using matt) to aid with adhesion and still get a smooth finish as the clear will fill the sanding marks.

Edited June 5, 2010 by thegunny

[David Hingtgen]

Ok, I was specifically referring to the most commonly-used ones for planes/valks, from Testors/Tamiya/Humbrol etc.

[Ghost Train]

As long as the bare plastic has cured, it should be fine ...

On a more serious note, I normally stick to the types of "normal" clears that David mentioned. Never had problems against unpainted surfaces. In theory though, I can see the clear being "weaker" since it's just interacting directly with the plastic, and not bonding with a surface already coated with the same type of paint or a layer of primer.

In practice though, I've never noticed the difference.

[anime52k8]

thread bump.

Just a general question about clear coats.

what's the best way to do a flat clear coat over decals? I'm looking for something that will give a very flat finish and will hold up to light handling.

Till now I've been using Testors dullcote but I'm finding that even once it's dry it's still a little delicate (heat and oil from your fingers enough to mess up the finish). I've also been experimenting with future mixed with Tamiya flat base, but so far it keeps turning out blotchy (i.e. the flat base isn't being distributed evenly throughout the future). I've been thinking about trying Tamiya TS-80 flat lacquer spray paint, but I'm worried that it will eat the decals underneath. (I also read an article online claiming that Tamiya clear lacquers will crack if you don't apply them within half an hour of laying down the underlying color layer. That honestly sounds like BS but I'd rather find out first hand. )

tl;dr: I'd like to know how to get a really flat finish using just future (if that's even possible), alternatively is Tamiya flat lacquer safe over decals.

Edited June 20, 2010 by anime52k8