Brush painting with Tamiyas

Mix some of the paint with a slow-drying acrylic blending (retarted) medium on a plalette, dip your brush in a acrylic flow improver, then dip the brush into the paint. This will thin the paint to flow better and keep it from drying out so you have time to work with it.

My problem with it is precisely because Tamiya acrylics drys WAY too quickly. It literally dries on the brush seconds after exposure to air, then it dries into small grits onto the brush that's not even washable by water, having to use thinner to remove. In general flat colour is more prone to drying than their gloss range. Their semi-gloss can be treated the same as flat in terms of drying time. Most of local HS where I get my paint supplies do not have retarders.

If I must, I would thin with Tamiya thinner + water extensively and apply thin coats, and apply it multiple times to achieve eventual coverage. This obviously does not work well on small/complex surfaces due to paint pooling and is for large surfaces only. With Tamiya acrylics if you can see brush strokes, it's already starting to dry and it will not end well for you. Better it be a pool of thin paint instead.

I try to avoid brush painting large areas with Tamiya acrylics, but I've found that one part Tamiya X-20A thinner to three parts paint makes it flow that much better and retards the drying a little so you don't get as much "pull-up".

Lay down one coat, do not be tempted to even it out after it starts drying. Let it cure overnight before re-coating.

When recoating, do not linger on any given spot or it will "burn through".