Solvent for carbon/soot on a brick wall?

well acetone of cellulose thinners will take out styrene, but IME carbon is there till abraded away, so pressure washer my be a place to start or wire brush.

Such carbon would not be soluble in anything, I wouldn't have thought. What about a blow torch - that would burn it off but would it harm the brickwork/mortar?

Well biological washing powder/liquid is designed to tackle organic [ie containing carbon] stains so a strong solution and a good scrub might be worth trying.

It might work on some of the tarry (i.e organic) compunds left, unlikely to work on the sooty component which will be pure carbon.

Assuming it is carbon then the scrubbing might work if the brick isn't to much like a sponge but the soap powder is a waste.

What's needed is to convert the carbon to CO2, heat and oxygen or less heat and ozone. Maybe sparks from an electric fencer would remove the carbon, slowly?

If it is actually dry carbon and the wall is dry and uncoated then a blowlamp is best bet. If there is any moisture in the brick it may explode though... On the other hand, if it is a yoghurt pot or similar it will probably be oily and or not have penetrated. Scrubbing brush and detergent will remove it then.

Angle grinder, followed by car body filler.

Just thought it might help loosen it from the surface, but you both may well be right.

Alternatively, aren't there commercial caustic or acid products designed for just this sort of thing?

Or maybe try oven cleaner - some of that stuff is brutal. 'Try on a small patch first' as the instructions always say :)

Can I try WD40 first?

Organic substances contain carbon, but I wouldn't call elemental carbon organic.

There are some silly sods on this board. Why the hell do they insist on posting blind ideas that might make things worse for all they know?

If you put oil on the wall it will stain it. But I assume you can do what you want. Carbon sticks to grease but not to water. Therefore it will be holding onto the brick by friction which is low with carbon or because the brick is wet.

Anything else and it will dust off and smear to parts of the wall that are wet or oily. Have you tried brushing it off?

If it won't brush off it is sticking to the oily stuff that was produced in combustion. Wash it off with water and then get the rest off with a stiff brush and carpet cleaner or some effective detergent.

I'd suggest Ajax cream if it was something like a cooker you were degreasing. You might try it on a brick somewhere out of sight, to see if that will come off with a good rinse. I assume the cutting paste in it is chalk, so it should.

It's not - "organic" refers to carbon *compounds*. Elemental carbon is an element, not a compound.

Czjd! I meant greasy or oily

Organic refers to almost anything these days.

Really, its an alternative for 'Godly and Pious' and has as little meaning..

Er no. Organic in the sense I gave it has always meant what I said. Organic chemistry has been around prolly since Perkin discovered aniline dyes in coal-tar in the 19thC. The more recent pious usage is just that

- an invention of the do-gooders.

Weatherlawyer wibbled on Sunday 27 June 2010 09:25

Whoooosh!

Erm .. yes, that was my point. To be more explicit, there's no reason to think an agent designed to "tackle organic stains" would be any use on carbon.

Embarrassing

So is that what's on Victorian brickwork? I've just acquired some yellow stocks, and the parts that were exposed to the elements have a layer of soot/grime that looks similar to the baked on fat in an oven. I've got enough good edges for the front garden wall, so I'm not that bothered, but one assumes that nothing other than abrasion will shift it or blasting wouldn't be the norm.