If you use plaster to cover, be careful how fast it is. The reaction is quite spectacular and comes in just a few seconds.
To avoid getting trapped and having the time to apply the plaster before it hardens, make sure you have all the necessary equipment close at hand.
On the other hand, the speed of setting allows a "stripping" of the repair barely an hour after the application of the plaster.
Before applying a finishing coat, allow the plaster to dry permanently. Consult the drying time on the plaster carton.
Remove the formwork
About one hour after the plaster has been applied, remove the shoring, the plywood plate and the cardboard. The latter, softened by moisture, comes off without any difficulty.
To equalize the surface with the berthelée
Plasterers use a special trowel to scrape excess fresh plaster and even out the surface of the existing plaster.
If you do not own it, use a rigid spatula.
Sand and coat
If the repair has some gaps, replace them with plaster balls.
After final drying, sand with sandpaper and then apply a finishing coat, carefully smoothed.