I put 1 coat of flat Tamiya feild gray on a figure, I thined it a little with tamiya thinner.It dried with a low semi gloss.

Anyone know why?

Yes, I find that Tamiya Flat and Semi-gloss are both too glossy. I usually add some of their Flat Base to the Semi-gloss to get a true satin.
But now I use Vallejo Premium Flat and Satin with their thinner. They spray very well and are tough - invulnerable to enamel washes using AKi, Humbrol and A.mig enamel thinners. I stay away from turps.

I like this one personally. It dries dead flat!



I get it from Sprue Brothers.

so you spray or brush that on your figure when your done?

I spray straight from the bottle. I looks milky but dries totally clear and flat as a pancake.

so do you spray it on all of your figures all of the time or only when they are to glossy?

I use it pretty much all the time.