Vladimir
Detail Decepticon!
i have also used this urethane thinners lately after I used the white schmincke Airo color in my brush, this could not be cleaned with the airbrush cleaner.
but can the use of this urethane thinners not give problems after a long time?
I use only urethane paints reduced by big amount of the thinner. Paint can sit literally for weeks inside the AB and nothing happens to it.
Thinner can affect only the things mentioned by @basepaint in the post above. If you work carefully and your ABs are well maintained, there's no chance for the thinners to get to the parts of the tool that can be harmed by its action. I haven't changed any rubber seal for the reason of being spoiled by the thinners in the period of 10 years I have airbrushes.