Takes longer to work than what you think. My artex was over 30years old so who knows how many coats of paint it had. Don’t paint it on it has to go on thick. Use the cheap poly dust sheet to cover it and leave for 24hrs. Next day it scrapes off easily.
For older artic I recommend leaving on for at least 2 hours and a second coat may be needed.
I bought this to remove artex from my ceilings. First of all, the tub was delivered with a huge crack in it and product leaking out. As I only had two days before the plasterer came and the branches don’t stock the 15L tubs, I just had to hope the product hadn’t spoiled. For the application: I researched it, read all the reviews, followed them carefully. I was removing very thin artex with only one coat of paint over it. I liberally painted it on with a pasting brush, applied cling-film, let it soak for four hours, peeled pack the film, sprayed with water and… nothing. Did not turn to goop. Absolute waste of time. Turns out the plasterer charges £150 extra to skim over the existing artex, this tub of nonsense was £140. So I recommend just paying the plasterer more.