exterior wood/metal paint OK to paint stone window sill?

[bertietheblue]

I used a solvent-based gloss wood/metal paint to paint my back door, and now want to paint the sills of my garden windows in the same colour - can I get away with this or is masonry paint a must?

 

[emilybronte]

Do you really want very shiny stone sills? No.

I'd go for masonry paint (or at least eggshell) in a tone - or even two tones - lighter than the door, if I were you. Otherwise people will see it and think 'He was just using up that paint and it looks rubbish'.

 

[bertietheblue]

I see the point about taste; in any case, I have several other colours in exterior wood/metal paint but only white in masonry paint, and I don't want to fork out for another tin for 2 windowsills unless necessary. So the question remains: can I use exterior wood/metal paint on stone? Would it have unforeseen consequences?

 

[sparkwright]

Quite common for concrete sills to be done in gloss paint.

You will need undercoat first though, but I expect you know that.

 

[misterhelpful]

It will all depend on the type of stone you intend applying it to. Some porous stone can be holding moisture even when it appears dry and this is likely to cause the gloss to peel. Other stone will allow the gloss to adhere like the proverbial.
People have been glossing stone windowsills for donkey's years - many last for a good few years and many peel in no time at all - so you certainly wouldn't be the first person to do it. It may be wise to seal dusty or porous stone with a stabiliser/suitable primer first.

 

[emilybronte]

I agree with the technical advice above.

Aesthetically though, it's a poor choice. For the cost of one litre of eggshell or masonry paint (about £20) it's really not worth it.