Why does my plasterboard ceiling turn yellow and discolor? An expert can tell at a glance: there's a problem with the putty.

A friend told me that she was recently renovating her house, and everything was going smoothly until she saw the plasterboard ceiling. Her face turned pale; it had already yellowed and discolored in such a short time. She had no choice but to ask a professional to take a look, but the expert told her that it needed to be redone. She was furious!

Actually, I've explained before why plasterboard changes color after being painted. I told her again here, and there are two main reasons, which made her even angrier. First, the plastering process was flawed. The workers, trying to save time, didn't let the first coat of plaster dry completely before applying the second and third coats. This caused the color to seep through, resulting in discoloration. That's why I emphasized the importance of hiring a responsible contractor. I strongly advise everyone not to be tempted by cheap prices and think any contractor will do the job. Haha, you'll regret it later.

On the other hand, the decorators didn't apply a primer before painting, and the substrate was too alkaline, causing the paint to turn yellow. What's even more infuriating is that even though I paid a fair amount, they used terrible quality latex paint for me. No wonder it turned yellow (this mainly applies to walls other than plasterboard).

Besides the renovation workers, I also told her that there are other reasons why the walls turn yellow. For example, if the rust prevention work on the self-tapping screws (without rust prevention) is not done properly, it can also cause the ceiling to turn yellow. In addition, water seepage from the floor slab can also cause the ceiling to become damp and turn yellow, so waterproofing is especially important.

Based on her family's specific situation, the renovation workers also suggested some solutions, and I personally prefer the first one.

The first method is to remove the original putty and redo it. This is a permanent solution, so you don't have to worry about yellowing or discoloration anymore.

However, if you want to avoid the hassle, you can apply a new primer over the existing latex paint and then reapply putty. This can also cover up the discolored ceiling, but the effect is definitely not as good as the first method.

We must remember to apply anti-rust paint to the areas with self-tapping screws, otherwise the nail heads will rust and cause the drywall to turn yellow.