Fine cracks:

1. Wet the wall with a roller brush.

2. Remove the existing wall plaster.

3. Apply cotton duck or a specialized base cloth available on the market.

4. After applying, smooth out the putty.

5. Sand the roller latex paint once it's dry.

Large cracks:

1. Check if the plaster layer on the wall is loose; if so, smash it off and re-plaster until it's solid. 2. If the wall is made of gypsum board, apply paper tape to the joints.

3. If the wall cracks are only a few millimeters, and it's unappealing not to fill them, you can scrape off the putty and fill the gap with cement or plaster (mixed with some adhesive).

4. After the issue was resolved, applied bandages, filled in gaps with putty, and rolled on latex paint.

Three, Peeling: If there are local bulges or minor cracks and peeling on white or bare walls, you can scrape off the affected areas, smooth the edges after removal, then re-skim and apply primer before repainting. This allows for timely repairs, but there may be a slight color difference. Do not rush to fix cracks and peeling; first, determine the cause before proceeding.