Once fully dry, sand smooth, prime, and paint.
The most common cause. If the background (brick, block, or plasterboard) is too dry and porous, it sucks water out of the new plaster too quickly. The plaster on the surface shrinks while the plaster behind it is still wet, creating tension and surface cracks.
Not all plaster cracks are created equal. There are several types of cracks that can occur, including: plaster cracking when drying
Applying a single layer too thickly (over-thickening) can cause the material to sag and crack. Professionals typically apply two thin coats to create a homogeneous, crack-resistant layer.
Finally, human error can dictate the result. Applying a layer that is too thick in a single pass increases the volume of water that must escape, leading to significant shrinkage. Similarly, using the wrong mixing ratio—too much water or not enough binder—weakens the crystalline structure of the plaster, making it more prone to failure under the slightest stress. Once fully dry, sand smooth, prime, and paint
Plaster cracking occurs when the plaster mixture dries too quickly, causing it to shrink and contract. This shrinkage can lead to the formation of cracks, which can be unsightly and even compromise the structural integrity of the wall. There are several reasons why plaster may crack when drying:
External conditions play a massive role in the drying timeline. High temperatures, direct sunlight, or heavy drafts can pull moisture from the surface while the layer underneath remains wet. This uneven drying rate causes the surface to become brittle while the base is still shifting, leading to deeper cracks. Conversely, applying plaster in extremely cold conditions can interfere with the chemical set, weakening the overall structure. The plaster on the surface shrinks while the
Fortunately, there are several solutions to plaster cracking when drying. Some of these include:
A mix that is too wet will shrink excessively as the water evaporates. Conversely, inconsistent quality in raw materials, such as using low-grade sand with high water requirements, also increases shrinkage risk.