Any suggestions for cleaning 60 year old exterior limestone sills? I have already steam cleaned and that helped a lot, however some blackish stains remain in spots.I think where some lead calk leached down. Also tried clorox.
Thanks for the help
Brad
Replies
Brad, the mason that reused my 50 year old limestone sills took a disksander to them, they cleaned up very nicely. -Ed
Brad,
Sand them down and they will look like new
And don't plan on doing it very often.
Brad,
I've had extensive experiances cleaning limestone.
I let my wife talk me into installing 18" white limestone in an entry a house ago. What a mistake that was (see some pic in my websight below).
Anyway, what you need is a "poultice". Comes in powder form. You can get it at any tile supply house or HD. You make a paste out of it and trowel it over the area you need to clean. Put some Saren Wrap over it and leave it for a day or what ever the directions indicate.
I've actually used bleach instead of water mixed in the poultice on a really bad stain and it worked pretty good.
Sanding won't do much because a stain goes "into" the stone.Limestone is seriously soft! You need to penetrate it.
BE penetrated
Namaste
andy
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when i have to clean a masonry wall or stone i use a power washer, with hot water. My machine is 4000 psi with a 15 deg. tip. The psi should be turned down so not to cut into the stone. Limestone is very soft stone. The combination of the psi the right tip and most important the hot water. The hotter the better.