Failed Plastering with Gypsum Plaster

[ZipLock]

During my construction project, I repaired damages and did some simple plastering with Gypsum plaster. I think I've become quite good at handling the plaster, but the last time it didn't turn out well at all. When the plaster dried, it wasn't as hard as usual, and if you scratch it with a nail, it leaves marks.

While I was mixing and applying the plaster, it was as usual. Does anyone have an idea of what went wrong?

 

[anders07]

Either it hasn't dried properly or it might be absorbing moisture somewhere.
Are you sure you mixed it correctly and didn't get something else in the bucket?

 

[ZipLock]

Thanks for the input. I need to investigate if it can absorb moisture from somewhere.

I know it's mixed correctly as I only have one bag and the consistency was good.

How long is the drying time expected for gypsum plaster?

 

[b0hlin]

The drying time can vary depending on the layer thickness, humidity, temperature, etc. Normal drying time is approximately 2-6 mm per day at 20 °C and 65% relative humidity.

 

[ZipLock]

I can now report a few days later that the plaster has dried and is as hard as it usually is. Apparently, it dried much slower than I expected.