I spray Tamiya acrylics and sometimes need to touch up spots with a paintbrush. The problem is that a brushed spot is noticeably darker than the surrounding sprayed area. Is there a way to make a brushed area look reasonably close to the sprayed area in terms of the color tone?

So long as they aren't larges areas, being a slightly different shade won't matter. The filters, washes, and weathering will blend it nicely. It may even add more depth to the finish.

Chris, well, if you really do want the same matching finish, there is only one way: get the airbrush out again... the thing is, is the amount of effort (and anxiety ) that you might put into trying to make it match by some other method easier than simply doing it by airbrush again?

Well, I eventually had to AB again to touch up on a few occasions.

But what I don't understand is this. When I sprayed Vallejo paints in the past, their sprayed color tones were very similar to brushed color tones. Why does Tamiya look much darker when brushed?

Could it be that when brushed Tamiya goes on thicker or the solvents evaporate faster when airbrushed. Tamiya is a solvent based acrylic. Where as Vallejo in my opinion is closer to latex in its finish . Well that's just my interpretation .

When you brush paint Tamiya, being solvent based, you actually chew into the previous layer.

With Vallejo, which is water based and is a vinyl acrylic paint,
it sits on the previous layer and because it does not chew into that layer, touch ups are virtual impossible to detect.

This is the beauty of the Vallejo product, it is not perfect though as it does have some other issues, but touch ups are great.

Cheers,
Joe