Acrylic wash over Tamiya?

Tamiya acrylics are lacquer-based, believe it or not, and are extremely tough. You don't need any clear coat at all. Putting Future on it will ruin the effect because Future is self-leveling, and so will fill in the grain of the wood. Nope, just put it over the paint. Make sure you use a tiny dot of some kind of soap in the wash to help it flow nicely.

The myth is that you supposedly can't apply an acrylic wash directly to acrylic paint. This is bull. Ask a figure painter, they do it all the time, at least with water-based acrylics anyway. If you apply a wash with an acrylic that has solvents in it, you may get into trouble. Always test first. Vallejo's washes are water-based, so you will be fine applying over anything.

I personally don't buy the "Tamiya acrylics are lacquers" rumors, but that's a discussion for another thread.