Cleaning cement steps to remove blackish stain (may be shingle tar?)?

Question

We need to remove a black stain from our front cement steps. We have a 4BR colonial in Boston-West with a typical cement stoop of 6 steps and a small landing at the front door. Over several years, the landing and steps have become increasingly stained with a blackish color. Though it is *not* the case , it resembles a once-spilled black paint that was cleaned well and since weathered. It is not on the surface but more imbued in the cement's porous surface. To us, it doesn't look or smell like mold.

We are guessing it may some kind of shingle tar residue that runs off from main roof 2 stories above and/or the small 10" overhang we added above the door to reduce rain-pounding of the front door. The area faces south so it gets power-blasted with each rain storm, baked with each hot spell, and frozen with each winter storm.

Anyone have knowledge of :

(1) what the stain is

(2) how to remove it

(3) how to prevent it

Answer 1

1.  How old is the house(it might be something from an old house if the house is old-If its new then there's nothing from the roof that would cause this.

2.  Does this stain permeate all sides of the house.(is the stain here in front where you can see it.-Place some concrete pavers on the back side and see if you can get it happen on the other side of the house too.

3.  Have you tried any products to remove the stain.(like tide, dish washing, shacklee basic h etc)

4.  Take some to a lab and ask them to identify it for you.(local college)

Answer 2

If you have a friend with a pressure washer try that if not try bleach and soap and scrup it with a brush and wash with hose. If it truly is a tar........then you need something that breaks that down........that can be w d 40 or gas .......but you need to wash and clean it fast as not to spread the stain....what it sounds to me like is just something that needs a good soapy bleach wash...or pressure washer..........enjoy. By the way, try the bleach and soap first.......not oil removing materials.

Answer 3

If it is mold, a mixture of bleach and water will kill it.  Thats probably the easiest thing to start with.  Use equal amounts of bleach and water, and a scrub brush.

If it is tar, the bleach/water won't do a think to it, heheh... instead, you're going to need a solvent, like acetone.  Acetone IS flammable... so dont use any metal tools, or smoke while you're cleaning with it, hehehe.  Also be careful what you get the acetone on, as it will strip the finish/paint of anything it comes in contact with.  Use a stiff plastic bristle brush, or plastic putty knife, to work the acetone into the stain.

If you use any kinds of rags to soak up the loosened stain, be sure to drop them in a bucket of water, and set them well away from the house, overnight.  You can use water to rinse off the steps, if there is nothing growing right next to them, that you need to keep.

By the way, acetone can be bought in quart, and half gallon cans at most hardware, building supply, or paint stores... or wherever paint is sold.  Try not to get it on your hands, it'll dry your skin out....if you do, a good moisturizer will help.

If you can provide some photos, of the stain, and any roof edge above it, it would help to identify it.

As to how to prevent it, we really need to know what it is, before suggestions on that could be made.  First question I'd ask, is there a gutter system over it?

Good Luck

Answer 4

I bet you can remove your staines with a presure washer.Good luck

Answer 5

Well. Being that you think you haven't the solution, i would paint to your choice, as far as tar, Varsol

Answer 6

I had a black area on a wall and after cleaning it I think that it was either some kind of mold or the results of car exhaust fumes.

Either way a really good cleaner for mold and stains is "Jeyes fluid" applied with a deck brush.  If you apply it fairly concentratedly and leave it to work for a while it seems to clean anything.  Mind you it stinks like anything until it's washed away.  If you can't get it where you live, there's a similar stronger product which farmers use to sterilise dairies but I don't know its name.