Dry construction, edge joints of plasterboard panels with acrylic after smooth fleece

Acrylic as well as silicone are ultimately not miracle cures. You can basically do whatever you want, if you're lucky there won’t be any cracks. I would apply the acrylic before painting. You definitely have to expect that there will be cracks somewhere in 1 or 2 years. After just under a year, I also have a crack here and there. But they are so inconspicuous that I might just go over them with acrylic at some point. Maybe I’ll only do that the next time I paint the apartment, because if you apply the acrylic after painting, it usually has a different shade of white and you can often see that better than a small crack. So your painters are right. Maybe you can also incorporate the typical mesh tape. Then the crack resistance is higher.

Silicone would be better, much more elastic, but it is not paintable. Therefore, it is out. Acrylic is simply cheap, inferior stuff that you only use because it is paintable, inexpensive, and easy to work with, wet finger, zap, done. But it shrinks a lot, it is not very stretchable, does not adhere strongly... one could use MS polymer, strong adhesion, almost no shrinkage, very elastic, paintable. But quite expensive and difficult to work with, no wet finger, it sticks great even to saliva. That is why I am a fan of a delicate molding in corners covering the gap, that works permanently. Karsten