Tiling Over Waterproof Paint - Tile Advice

[dundeetiler]

Got a kitchen to tile that's had 2 different layers of paint on the plasterboard. 1st layer is that heavy waterproof paint and the 2nd layer is just an awful yellow. Tried to sand it back a bit but it's proving a nightmare. Debating whether to keep going with it or just score it with a blade since sandpaper and wire brushes are failing.

 

[Dan]

If you score through the plasterboard paper you take the strength away, apparently.

Do the paint test. Stick some duct tape on it for a hour, then rip it of (do it in a few different places) - If nothing comes off, you can tile it. I think. Is that right lads?

 

[On one]

Is it finish plaster on plasterboard or dry lining over plasterboard?

 

[On one]

If you score through the plasterboard paper you take the strength away, apparently.

Do the paint test. Stick some duct tape on it for a hour, then rip it of (do it in a few different places) - If nothing comes off, you can tile it. I think. Is that right lads?

Depends on the quality of the adhesive on the tape?

 

[Flintstone]

On a kitchen splashback I often give it a good scoring up if it's painted skim and the paint is well on there, then prime it and tile. Different story in a bathroom

 

[dundeetiler]

I done the tape test beforehand with decent gaffa tape and not a drop of paint came off. Just a little uneasy with it being thick waterproof stuff.

Just the drylined. It was a new-build about 20 bloody year ago that's just been painted over a few times.

I'll just score the paint in the usual crisscross and pray it doesn't take the paper off the plasterboard.
Cheers guys!