I had need to cover a ceiling stain and thought easiest would be a coat of oily white gloss it won’t bleed through, then emulsion later.
I had a tin o Dulux Weathershield external 6yr brilliant white gloss. New and unopened but likely bought a few years ago 'cos I don't remember when, why or where.
I opened it up… Burgundy all the way to the bottom..
pgk