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pffreestyler3 Jul 2019 11:34Hello,
Here is the situation: We applied gypsum plaster, and around the ring beam and lintels, the plaster dried very slowly. That makes sense since concrete doesn’t absorb water, whereas the Ytong wall dried very quickly. In the end, there were still some damp spots left, mainly on the lintels above the doors. When you ran your finger over these spots, there was no visible change at first, but after a few minutes, the area appeared dry.
We have now painted directly onto the plaster, and the areas where we wiped with a finger stand out from the rest. There are clearly visible streaks. We have painted the lintel three times already, but there has been no improvement.
The surface is completely smooth—so there are no scratch marks, especially since we wiped the surface gently with our finger.
What could be the cause? Is there still more moisture in those areas compared to the rest?
Here is the situation: We applied gypsum plaster, and around the ring beam and lintels, the plaster dried very slowly. That makes sense since concrete doesn’t absorb water, whereas the Ytong wall dried very quickly. In the end, there were still some damp spots left, mainly on the lintels above the doors. When you ran your finger over these spots, there was no visible change at first, but after a few minutes, the area appeared dry.
We have now painted directly onto the plaster, and the areas where we wiped with a finger stand out from the rest. There are clearly visible streaks. We have painted the lintel three times already, but there has been no improvement.
The surface is completely smooth—so there are no scratch marks, especially since we wiped the surface gently with our finger.
What could be the cause? Is there still more moisture in those areas compared to the rest?
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pffreestyler3 Jul 2019 12:00Drying time: nearly 3 months
Paint: Renovo Crystal White
Primer: none applied, painted three times with color. The other walls only required 1-2 coats – also without primer.
Plaster: no additional treatment, was smooth like a baby’s bottom from the start
Well, a guess:
A sinter layer usually forms on the plaster, and you may have wiped it away by rubbing with your finger, so the substrate here absorbs moisture while the adjacent area does not.
To achieve a clean finish, plaster is typically sanded and primed.
Sanding the lintel with fine sandpaper, then applying a primer (deep penetrating primer), and repainting afterward should solve the problem.
A sinter layer usually forms on the plaster, and you may have wiped it away by rubbing with your finger, so the substrate here absorbs moisture while the adjacent area does not.
To achieve a clean finish, plaster is typically sanded and primed.
Sanding the lintel with fine sandpaper, then applying a primer (deep penetrating primer), and repainting afterward should solve the problem.
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pffreestyler3 Jul 2019 13:05Okay, thanks, we will give it a try.
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