Cleaning stained chimney bricks and mortar

[slindo]

We have a brick chimney in the center of our house, completely exposed. Over the years some stains have developed on the bricks and mortar beneath the thimble. I suspect it is from rain water coming down the chimney and collecting soot and creosote on the way down rather than from creosote directly as the result of combustion leaking out because the staining is not very heavy and has taken a long time to develop.

Anyone know any tricks cleaning it off?

 

[EatenByLimestone]

You can try TSP. It used to be Tri Sodium Phosphate, but now they got rid of the phosphate. They still call it TSP though.

Muriotic Acid might work too.

Test a small patch in some not easily seen area if you use the acid. It's some strong stuff.

Matt

 

[PLAYS WITH FIRE]

You can try a little bleach in water. I used it to get some stains off the hearth. I did a little at at a time because I was afraid it would make things too clean.

 

[slindo]

Forgot all about TSP, I'll give it a try and if that doesn't work, maybe muriatic acid.

BTW TSP is one of those odd things, "good old really works" products that when you go shopping for it half the stores will tell you has been outlawed and will try to sell you TSP(subsitute) the others will have the real thing. I actually called up our state EPA to find out what the deal was and guy said it is legal for some applications and not for others, but the main reason for outlawing it at all was to prevent is use in places where it will end up in ponds or lakes. Since we have our own septic tank, and miles from the nearest water, I don't feel to guilty using it, and recklessly go through an 8 ounce box of it every 10 or so years.

 

[My Oslo heats my home]

muriatic acid and a stiff long handled brush.

 

[Ducky]

your best bet is to sandblast it. I actually do it professionally. Comes out better than any chemical. But expect it to be a 2-3 day ordeal. 1 day set up. 2hours to blast... 1 day clean up.

 

[DianeB]

If they are rust stains as well, try the bathroom product called CLR