Tamiya X-21 and X-22 for Clear Coats

Update (10-Aug-2016):

It's been two years since my original post. I realized I should write an update based upon my experience when working with plastic model kits rather than game miniatures.

Try lacquer thinner.

Consider using Tamiya's lacquer thinner instead of Tamiya's acrylic thinner. In fact, I now favor the lacquer thinner, espeically for gloss coats; it doesn't seem to matter much for semi-gloss or flat. I've discovered that the gloss finish is generally much smoother and avoids the dreaded "orange peel" look that you can sometimes experience when using an airbrush. Definitely give it a try on a piece of scrap and judge for yourself.

Apply no more than 2 light coats and allow to dry.

Go easy when spraying flat coats. If you build-up multiple coats during a single airbrush session, you may be at risk of applying too much and creating a milky white finish. Disaster! It won't be obvious until after it dries. Try to spray no more than 2 light coats and allow to dry overnight. You can always apply more the next day. Honestly, this milky effect can happen with any flat finish product including the popular Testors Dullcote. I've learned this the hard way. I routinely apply a "wet coat" for a smooth finish when painting as I wrap-up any given airbrush session. However, I've learned to avoid that practice with any clear flat finish and I've had good luck ever since. Sorry - I should have shared that insight in my original post.

It may sound like a lot of effort getting to understand these products, but I think it's worth it. In my experience, I personally believe the Tamiya finishes are much stronger when compared to Dullcote or other acrylic products. That's an important consideration for weathering. But who knows? Try to remain open minded for new products. Maybe the next great thing is around the corner!

Original post:

Not sure why this pops up in forums so often, but here is how you can use Tamiya’s products to airbrush a clear coat. I generally prepare a 50:50 mixture of paint:thinner and spray at 10 to 20 psig.

The following table describes the mixtures using volumetric percentages:

Finish	Acrylic Thinner X-20A	Flat Base X-21	Clear X-22
Gloss	50%	0%	50%
Semi-Gloss	50%	5%	45%
Flat	50%	10%	40%

And this table describes the mixtures using volumetric ratios:

Finish	Acrylic Thinner X-20A	Flat Base X-21	Clear X-22
Gloss	10	0	10
Semi-Gloss	10	1	9
Flat	10	2	8

Flat base is not at all intended to be used directly; it must always be mixed with another paint. More information may be found here on Tamiya's web site.

I generally prefer to use Duplicolor gloss clear spray as a durable finish for game miniatures, followed by a light dusting of Testors Dullcote. However, once the cold sweeps in, I can no longer spray paints outside. Tamiya clear is a nice alternative and I can airbrush it indoors. I do believe a lacquer-based clear is stronger than acrylic, yet that may just be my own perception. Honestly, I have no way to really measure this and can happily say that both techniques have held up well over the years.

Good luck!