Several years ago our house was remodled. One of the projects was plastering over the old brick with a sage green colored plaster. It was sealed, once. Parts of it need to be cleaned to remove the soot and I don't know what to use to clean it, but to prevent any damage. Any help would be appreciated.
Sorry, for some reason I missed this when you first posted it. Couple questions...Is it plaster or is it concrete? You say concrete in the title and your second post, but in the first post you say plaster. And is it inside or outside the house? If it's concrete and it's outside, and the concrete is stained (rather than painted) then a pressure washer with some concrete cleaning solution should do the trick. If it's plaster or if it's indoors or if it's painted concrete then the pressure washer is not a good idea, so I would try a mild cleaning solution and a soft scrub brush--start off gently at first to make sure it's not going to damage the surface (if it's stained concrete indoors, you can be pretty rough on it, but if it's plaster or painted concrete then you'll need to be a bit more careful/gentle).
Thanks ecrane3. It's inside, surrounding my fireplace, therefore sooty. Now that you brought it up, I don't really know if it's concrete or plaster. I know it is not painted. It is stained. Any recommended products or solutions?
Is the surface really rough or is it sort of smooth? The Mr. Clean Magic Eraser would be my first choice for something like this, but if the surface is rough it'll chew through hundreds of them before you get the job done. Abrasive cleaners like Soft Scrub might also work well in combination with a good scrub brush if the surface is a little rougher. Soot won't dissolve in a cleaning solution like many of other types of dirt will, so I think the key will be the scrubbing/abrasion rather than what cleaning product you use. The Magic Eraser really does work like magic on a lot of things that you just can't get clean with anything else, so I hope your surface is on the smoother side so that you can use it!
I'm not sure what it would do on soot, but Greased Lightning will melt most stains. Cleaned 20 year-old cigarette stains with it. Sprayed - waited 5 minutes and wiped away. Then finished with plain water on a towel to remove what wes left.
If the surface is rough, might have to scrub with a brush and clean water after softening the soot. Spread some old towels to catch the runoff, and use a spray bottle with plain water to clean the residue - should not splatter too much.