Recently submitted to the FSM tip department...
FSM -
I may have discovered a potential incompatibility between Testor's new Universal Enamel Thinner (red metal can) and Future Floor Polish.
For nearly 15 years, I have been using the almost universally recommended detailing and weathering method of adding enamel washes over a coat of Future which protects the enamel and metalizer paints beneath. I apply the Future in several consecutive, light layers and allow the entire coat to cure for 4-5 days. In the past I've wiped the wash away using Testor Airbrush Thinner (black can) and q-tips, cotton balls, or tissue paper, always with excellent results.
As I believe Testor Airbrush Thinner is no longer available, I used the Universal Thinner (red can) for the first time on my most recent project. Unfortunately, I discovered a potential problem when attempting to remove a wash I had applied over Future. Using a q-tip and just a bare amount of thinner, the Future began to soften after only a few strokes to the point that cotton fibers became embedded. In trying to remove the cotton residue with more thinner, I rather quickly stripped the Future and the underlying paint down to the bare plastic. This also occurred in spots where I had several paint-Future-paint-Future layers.
I should note that I mix my washes using enamels, a small amount of clear gloss finish, and thinner. I let each wash dry at least a day after application.
After some experimenting, I believe the issue is with the Universal Thinner. Maybe it's too strong even for cured Future. And since I'm now using that same thinner to make the wash, I'm possible already weakening or otherwise affecting the Future during application of the wash before unknowingly delivering the coup de grace when I try to remove it with more thinner.
I found that Turpenoid did not cause the same problem, but unfortunately I don't have any more of the old Airbrush Thinner (black can) to determine if it's a problem with my bottle of Future, which admittedly is about 13 years old. I did finish a project a few months ago using the same bottle of Future and Airbrush Thinner and did not have any problem with removing washes applied over the Future.
Given the number of sources (including countless FSM articles) which recommend using Future to protect paint from subsequent detailing and weathering methods, I imagine there are a lot of modelers who would be interested in this potential problem.