Jim Scott wrote:
Are proprietary 'Stain block' paints any better than oil-based undercoats?

I have used the stain block that Screwfix sell to cover water marked
plaster. I found the yellowing stain came through the stain block as
well, which looked suspiciously like normal emulsion to me. Eventually
I managed to cover it, but it took several coats of stain block and
several more coats of normal emulsion (Dulux trade satin).

Make of that what you will.

--

Steve F