How to Restore Cracked Plaster | howtos | DIY
A previous repair to the plaster was made with a drywall patch and gypsum. In this case, use a limebased plaster because gypsum and lime create a negative reaction. To smooth out the rough patch, we skimcoat the area with more gypsum compound and smoothed down our finishcoat even with the patch, feathering it in for a smooth appearance.