Lime-gypsum plaster crumbly and therefore defective?

Hello everyone,

the lime-gypsum plaster was applied in October/November (screed, underfloor heating still to follow). Today we wanted to remove some sockets from their covers. When knocking off the plaster, it turns into the finest crumbs (like trickling sand). Is it normal for this plaster to be so soft? Even the slightest bump will leave a mark?! Should we have used gypsum plaster or is the quality poor? (in the bathrooms there is lime-cement, which is noticeably harder, but also partly crumbly when chipping off).

Wintersonne

Well, you can't seriously judge that in a general way and from a distance. But it sounds strange. Are there any photos?

1st image: after the first two hammer blows, which were not excessively strong
2nd image: after further hammer blows, the whole thing starts to crumble. Or is that normal?
3rd image: here you can see the fine crumbs, you can simply "rub off" the plaster at the edges (with the hammer or another hard object)

Looks quite normal in the pictures. I cannot judge whether the plaster is excessively soft.

You can already scrape off the plaster with pressure using your fingernail (Bild 3), then it continues to crumble... I am tempted to test the plaster in our rental apartment to have a comparison, but I think I should leave it... Here, the plaster has also withstood sharply shot balls without damage, I somehow can't imagine that here. But as I said, I lack the experience.

Which is not even remotely comparable to a hammer. Especially not with a cavity behind it. You are probably confusing plaster with mortar.