For years I used Floquil 'Dust' as a flat overspray on Models that I painted with enamels. Airbrushing a light coat gave me a great dead-flat look that also dulled the intensity of the colors, while heavier coats gave in increasingly dusty look.

However, Floquil Railroad Colors have gotten harder and harder to find, and don't seem to work very well when sprayed over Acrylics. I recently tried spraying Dust over an LVT-2 painted with Tamiya acrylics, and instead of getting the expected dead flat finish, what I ended up with was a semi-gloss sheen. I imagine this was a reaction between the Floquil and the Tamiya Acrylic.

So, I'm looking for a replacement. I know that Testors/Floquil makes "Dust" in the Polly-scale line, but I have never had good luck airbrushing Polly-S/Polly-Scale paints. The airbrush clean-up is a nightmare. What I'm looking for is a mixture that I can spray over acrylics to give me similar results to what I got with Floquil Dust over enamels. I've thought about trying to mix Flat base with clear and a buff or yellow shade, and then thinning it way down.

Has anyone tried this who can give me any ideas/pointers.

Vallejo Matt in their Air line.....drop it in the airbrush and go. Gives you a dead flat finish.

They also have a gloss and a semi-gloss in the same line.

I had not tried the Vallejo as none of my local shops stock it, while they do stock Tamiya and Testors/ModelMaster. Will have to order some.

I'm a huge fan of Vallejo but I don't think they have, could be wrong because they have way over 400 separate products in their paint lines, anyway, I don't think Vallejo has a "dust" specific product. Lifecolour does. At least two Dust 1 and a slightly warmer dust 2. Both are available in their 6 bottle "rust" set and I assume they are available singly.
I've been testing them and the finish is quite beautiful. "BUT", always a "but", they have to be thinned down to more of a glaze, a very thin glaze, 5-10% "dust" and 95-90% acrylic thinner or distilled water. I prefer Gunze "Mr Thinner" right now. My problem with water is that it seems to "soap" up when mixed with an acrylic paint. The thinner alleviates that problem plus it flows better. 10% paint might be too much. The paint right out of the jar is simply white and light buff paint really=fully opaque. There is supposed to be some grit/tooth in all the rust set paints and there is but very subtle though visible and quite nice. I would recommend the whole set too.
I got my Lifecolour from John, "the tankrat"-he's seems to have all of the Lifecolour line
my25cworthbobC

Tamiya Buff thinned about 95% with thinner. If you want a couple of layers of color, used the Desert Sand and do the same thing.

If all your shop carries is Testors and Tamiya...that would be your best bet.

I use Testors Clear Flat Lacquer, and thin it down a bit with hardware store Lacquer thinner... then mix in some Mig pigments in the color I want the dust to be. This is good either stand-alone or in conjunction with more pigments applied with a brush on top of the dusty base coat.