Tamiya matt varnish

I wonder if you are using Flat Base X-21. If that is the case, you might have chosen the wrong paint. Flat Base X-21 is to be used to mix with other paint, mainly gloss paint to produce a paint with more flatness. X-21 is not supposed to be use as a finishing paint. I had the same problem as you did. Some paints, such as Gunze H029 or Micro-scale flat finish, despite they claimed to be flat finished, I still get the some minor symptom of white power and the flatness is not ldeal(actually they are like stain). So far the only success I've got is from Humbrol flat. But Hubbrol flat is enamel, so you must be very caution in ventilation. Get enough air and with no flamable fire around. Some member mention Model Master acrylic flat finish is good, perhaps you might want to try it first. IMHO, for airbrush use, I suggest you try acrylic paints first.

As Anthony said, Tamiya Flat Base is not meant to be used alone, even if thinned. You have to mix it with water-based acrylic paint. In my case, I either mix it with Tamiya Clear (a gloss coat ) or Future to make a final flat coat. Remember that you only need a small amount of flat base to create a flat sheen; too much and you get that white powdery appearance. Try 1:5 flat-base-to-gloss ratio for starters. You can add more flat to make the sheen duller, if you want. Hope this helps.

Cheers,
onyan

Thanks guys.. both of you were correct.

I was using the X-21 alone. I now know what I need to do..

Thanks..

I strongly recommend finishing with lacquer-based flat coat such as Testors Dull Cote. Lacquer (nitro) based clear has better physical properties (strength, resistance to scratches) and better chemical properties (once it dries it is 100% resistant to water and solvents).

I had finished a tank model with Gunze Sangyo acrylic flat clear, had a drop of water with traces of isopropyl alcohol in it fall on the surface of the finish and there was a strong chemical reaction forming a white deposit that wasted the finish and the model had to be repainted. 100% pure water still left permanent spots on the acrylic flat finish.

But nitro-based clear finish is like tempered glass after it dries. It's veritable chemical armor for your model.

The bonus of Testors Dull Cote is that the luster is just what it should be-neither too glossy nor too flat. Some clear finishes on the market are too flat, notably the Model Master (Testors) "Akryl" flat clear (acrylic). This particular flat varnish also alters the color of the model quite dramatically!!! No such problems with Testors Nitro although remember not to spray more than one coat as consecutive coats will darken the color a bit at a time until the model looks too dark. This gradual darkening is true for all brands and types of clear varnishes.

Another problem to be aware of: all clear varnishes are extremely sticky while they dry which poses a serious risk of lint and pollen from the outside or inside of the home getting stuck all over the surface of the model. If you can get away with spraying just the basic color (enamels are best if you're not finishing with clear) and then weathering and applying dry transfers you will get the best overall quality of finish. Every time you spray a model and then come back the next day to apply a new coat you're begging for lint and dust in the finish, even if you do your best to dry the model in a lint-free environment.

You can spray the Testors Dull Cote flat clear straight from a can which saves time and stress setting up the airbrush.

Must admit, I've used Gunze flat acrylic varnish without any issues on a number of models.

I like the finish of this varnish too, as it leaves just a trace of sheen, which I find suits my Luftwaffe models perfectly.

Karl