>>7890945So here's what I found: The thinner I use is Supralux H-100, and according to its safety sheet it's 94% naphta and 6% 1-butanol. Tamiya cement according to it's safety sheet (I use Gunze Cement, but this was the one I could find) is 50% acetone and 50% butyl-acetate.
Now according to Wikipedia butyl-acetate is manufactured from butanol, so maybe it works in reverse and it can weaken model cement welds. Now I'm in no way a chemist, but it sounds like it could make sense. So for now I'm switching over to the hydrocarbon solvent I use for work (again, hard to translate, it's either petroleum benzine or petroleum ether or whatever) or try to get more pure naphta from somewhere.