How is the cracking of the putty layer caused? What should I do?

here are many reasons for the cracking of the putty. There are external reasons and internal reasons. From the outside, dry and wet changes form dry shrinkage cracks; temperature changes and thermal expansion and contraction cause temperature cracks; wall structure deformation static load causes structural cracks. Internally, factors such as product quality, construction process (batch thickness, interface treatment), and maintenance methods may cause cracking of the putty.

Solution:

Micro-cracks caused by dry and wet, temperature changes or batch scraping: can be sanded, brushed and solidified, and carefully controlled;

The large crack caused by thick scraping, etc., after the eradication, the wall is fixed, and then putty;

Large cracks caused by wall cracking, after painting, wall coating, paste mesh cloth, and then putty scraping. If the wall crack is large, the wall crack treatment plan should be treated.