After a good chat with Paul at Holman Paints, I thought I should share this information, because What paint can I use where heat is involved? is a regular question, and I give the same sort of answers as below, (not quite so detailed!) but because the emails are one-to-one, nobody gets to read them…
As a rule of thumb, if you can touch a surface without being burned, a standard paint will work fine, providing standard preparation practice has been followed.
And if the surface to be painted is more than 30-40 cms from a heat source, you can use any standard paint without too much fear of failure.
i.e. any emulsion, eggshell or gloss paint will work on metal radiators, and on brick or plaster behind a stove, with a 30-40cm gap, standard emulsion paints are heat resisting too.
Intumescent paints are designed to stop the spread of flames, and to protect the substrate. So they swell and create a protective layer.
BBQ paint is ok on metal surfaces reaching from 250 to 450+ degrees
Stoving enamels will only cure on very hot surfaces.
Heat resisting paints have no insulating properties
##What about old railway sleepers as part of a hearth arrangement for a wood burner stove?
This was a question from a reader recently.
30-40cm distance is safe for most standard paint to withstand temperatures where you can still touch the surfaces. Ordinarily a penetrating sealer and / or lacquer of your choice will work on new timber.
However, railway sleepers are problematic, being impregnated as they are in all sorts of nasty tar preservatives,
if the sleepers get hot, the voc will be liberated! so heat may cause health issues. Sparks may cause fire issues.
sleepers are not recommended for painting with anything clear, as the tar etc will likely leach through the coating.
You could use aluminium leafing primer as the base of a solid coat system which should withstand the leaching preservatives, but really, the old sleepers are best left au naturel and away from the stove.