Tamiya acrylic vs. Humbrol Gloss varnish.

[Gern]

Hi guys, back again.

I brush painted some Tamiya acrylics onto some small parts on Friday night. I've tried to brush on a coat of Humbrol gloss varnish this morning and it's fetching all the paint off. Are they incompatible or is there something else going on?

Both the paint and varnish are neat straight from the jars.

[A_J_Rimmer]

Okayyyyy, trying not to sound like an expert here, which I'm not, but being a life long brush painter I ran a few experiments with painting Tamiya acrylics a few years back, because I'd heard what a PITA it can be to brush-paint.

First off, I suspect there was a compatibility issue, in only that enamel clears are hotter than water based clears, but I suspect the main issue was with the Tamiya paints.

Tamiya paints are notoriously bad for brush painting because, asides from the crap coverage and quick drying time, they have a tendency to lift when you apply a second coat (or even go over a dried section whilst still applying a first) due to reactivation. They are also rather fragile and don't tend to adhere to the base plastic very well - a primer it pretty much a must-have.

There are things you can do to make it better, in fact I got it to the point where I could bash it around quite a lot, but it gets to the point where the hassle is not worth the effort. Certainly trying thinning it with Tamiya's thinner and adding some Tamiya flow enhancer - that will improve things.

But prime, prime and prime again.

I do suspect the enamel paint/clear reactivated the Tamiya paint and just lifted it off the surface. As I said above, if you stripped and re-primed the part, and then painted and clear coated it, you might have better luck.

[Tim Marlow]

Is the Humbrol water based acrylic or enamel? If enamel that could well be lifting the Tamiya as Arnie says. Enamel thinners is quite aggressive, I’ve even had it detach glued on parts when I’ve used enamels as a basis for a wash. On the other hand, if it’s acrylic then the only thing it can be is the bond between the model and the paint film failing.

[Gern]

It's the acrylic varnish so I suspect you guys are correct with the paint/plastic bond. Not to worry. I daresay I've got a Vallejo colour that will be OK so just gotta remove what I've done.