Getting paint of a stone lintel/windowsill

[Hicky]

I had the windowsills an lintel painted by a decorator last year and they've gone crazed/cracked....they weren't before.
I'd like to clean them back to bare stone and start again having a good finish. How best am I to take off a few layers with speed and a modicum of care for my windows/seals....or am I better off stripping the seal off also, painting them resealing the areas required?
I'm thinking a strong scraper plus some heat where needed to soften the paint....I'd rather not use chemicals.

 

[Darius_Jedburgh]

If you use heat you can leave marks on the stone.

 

[Hicky]

I wasn't thinking a blow torch, more a heat gun. I'll be painting over once I'm done....also paint recommendations...?

 

[Mark Grant]

If they are real stone the paint may have suffered a chemical reaction. If you strip and repaint use an alkali resisting primer, maybe even 2 coats to make sure of good coverage.
Edit. This is assuming you will be using oil based paints.

 

[Badger_Boom]

Try these chaps. They make specialist paint removers for things like external brick and stonework. We've used some of their stuff to get unwanted paint off the outside of bits of our house and it worked well (although you'll need to don plenty of PPE because some of it is a bit caustic).

PS. The reason it can crack, craze and do other aesthetically displeasing things is usually because it wasn't meant to be painted.