Hi guys. Recently I have painted a ceiling of my own classroom but it seems that the paint won't stick on the ceiling because the ceiling has some white dusty particles on it. Whenever I start rolling, the first time it will stick but as I roll it down again it will come off. Do I need to scratch off the first layer first? Or what should I do? The paint I'm using is not genuine paint. I think it's something of paint mix with water that kind. Cheap one.

why dont u clean d ceiling first with water pipe pump, d one dat they use to wash car...

I heard rolling a layer of detergent would be helpful for the peeling paint to come easily, then you can paint the final coating

Wow..lol. I tried using water to clean but it seems that the white powder still exist.

So you meant paint first, clean the paint and paint again?

Get a specialized primer for this prior to decorative paint