Removing Smoke Stain From Artificial Stone

In My Humble Opinion
1

OK, I’ve played with some of the ideas on Google results. The stains are still laughing over the experience.
If this were real brick I’d have id sandblasted, but it is some form of cement or the like - the nice, flat surfaces would be gone.

I’m not looking at inside the firebox - just the fascia - some bright people put in a very nice, expensive door unit. Unfortunately, this was another DIY job which really, really, shouldn’t have been.
Instead of drilling holes for the mounting brackets, they found the big lever with holes already drilled! They just puled it all the way forward, and used baling wire through one of the holes. With the weight of the unit, it worked perfectly.
Yep, a nice, shiny fireplace with the damper permanently closed.
On top of that, they bought a log holder way too small and put in a big fire - one of the bits fell forward against the bottom of the door, so the big, expensive unit now has a large scorch on it.

Anyway - the 10" or so which were covered by the door are heavily stained and I’m looking for someone with experience.

Have tried TSP, salt, dishwasher detergent. I have pool shock, which is a 52% calcium hypochlorite powder. Nasty stuff, and I’m afraid it would make for uneven color - as in too much bleach (which is a 6% solution of the same stuff).

Ideas?

2

The best thing I have found on a real fireplace stone is just regular old Comet Cleanser (just enough bleach) I know people pay money to have their fireplaces acid washed. And I would guess muriatic acid from the hardware store, diluted 4 to 1 and carefully applied would work well. Might be worth a test spot at least.

3

Actually, I have muriatic acid. Hadn’t thought of that - should be easier to control dosage, as it it already fairly weak - its used to adjust pool ph.
Thanks for the tip.

p.s. - have no idea how “brick” got into the post - it is fake stone, not fake brick.

4

go to a building materials store, better a brick and stone materials store and ask them how to clean stone. they will have products.

stove and fireplace stores will also have glass cleaning products. you don’t want to scrape or use abrasives on the glass.

the products will likely be in a gel or paste which will stay in place while cleaning.

5

The glass is gone - he scorch ruined the unit.
We’re now dealing with artificial stone - probably cement, formed in molds and dyed to simulate natural variation of sedimentary stone (limestone, sandstone, shale, slate, etc.
This stuff looks like none, but this was a cheap-ass development, and the corners (hell with cutting), were skipped entirely.