Today's Apr 19, 2019 and the test started on Nov 19, 2018. For all this period one airbrush with new O-ring installed was loaded with the urethane paint. Airbrush had "C" cup with small hole in the lid, so from time to time I was pouring in some reducer for the reason the paint wouldn't dry in the cup (reducer evaporates from the paint).
This part of the experiment has been done for the reason to find out how solvent proof new O-rings might be. The result - yes, they are absolutely solvent proof!
Here's a photo of just removed O-ring from the AB, cleaned and wiped off with the paper towel (on the right) and absolutely never used similar O-ring (on the left).
You can see some white particles on the O-rings, these are just particles from the paper towel, in reality the seals themselves are in like new shape (actually one is real new).
So, I can be sure that if the airbrushes will be loaded with the urethanes for a month project, nothing will happen to the seals and the tools can be freely used for this long period of time, or even more, if required. I mean no matter how long the project period might be, the O-rings will bear it giving the same smooth performance of the needle, predictable spray start and other features mentioned in this thread.
Definitely, this part is for professional use!
