OT: Removing a snap line chalk mark from concrete

Try a strong ammonia solution, be ready with some form of extraction, like a good wet-vac rather than letting it spread. Try hotter water, even near to boiling, water dissolves more the hotter it is. You might need to go with a bleaching agent, like oxalic acid, peroxide, or even clorox...DON'T MIX THEM!!!! Use one, then after clean and dry try another. Don't hesitate to test your acid staining, it might have some effect too.

Worst case may be to embrace the red and snap a few more lines to make it look better, more geometrical, more planned and designed.

Stuart

If it really is an aniline dye as you suspect, denatured alcohol might work. I think I'd try, in this order:

- denatured alcohol

- washing soda

- chlorine bleach

The washing soda should be mixed with warm water at the rate of 1 to 2 cups per gallon. This is *not* the same stuff as baking soda. You can find it in the laundry detergent section of some (many?) grocery stores. Look for Arm & Hammer brand -- the box looks pretty much like a box of Arm & Hammer baking soda, too, except a lot bigger. Figure on paying maybe two-fifty, three bucks for a 3-lb box. It's fairly benign, but you don't want it in your eyes, and if you don't wear rubber gloves you'll soon know the precise location of every nick, cut, and scratch on your hands.

Washing soda and chlorine bleach are both bases, so it should be perfectly safe to use one after the other, and neither one will harm the concrete.

And I would have suggested muriatic acid, as it will "etch" the concrete.

If the house is @1950's, they might have been usig an iron-oxide type red in the "chalk".

Flash

i remember a (gallon jug) of blue chalk line chalk saying "... be sure you put it where you want it because there are no solvents to remove this chalk." or words to that effect. sorry for my (downer) $.02. based on that i'd imagine the only thing that would remove it would be sand blasting.

b.w.

After a Computer crash and the demise of civilization, it was learned "William Wixon" wrote on Thu, 26 Jul 2007

or Wire wheels and a grinder.

It is powder, it is fine powder, it has become one with the concrete over the decades. Removing it is going to be Work.

tschus pyotr

-- pyotr filipivich "Quemadmoeum gladuis neminem occidit, occidentis telum est. " Lucius Annaeus Seneca, circa 45 AD (A sword is never a killer, it is a tool in the killer's hands.)

Sorry to hear you have this problem also. Any red chalk is permanent. You can go to Irwin straightline's website for more info. I think red and yellow and black are permanent but, white, blue are easier to remove. I had an exposed aggregate driveway poured and they used red chalk to mark the sawcuts. I power washed the slab after a few days. It looked good so I sealed it. It brought out the red dye in the chalk and looks like someone bled at each crack. Acetone will dissolve the sealer but you still have to get the red out. Don't try an angle grinder with a wire cup. It will leave a nasty metal that will rust. I will be watching this post for ideas. Good Luck Lyndell

P.S. Maybe they should make Kilz stain blocker in clear :-) .

Oxalic acid will remove rust stains. If the red pigment is iron oxide, oxalic should get it.

Pete Keillor

On Wed, 25 Jul 2007 23:12:57 -0400, with neither quill nor qualm, Pete Keillor quickly quoth:

And if not, a pressure washer should bring it up where it could be wiped off.

- Metaphors Be With You -

When I was working on construction projects we seemed to have a problem with loosing the chalk lines because of water and foot traffic so we sprayed a rattle-can clear coat over them if they were exposed to the elements. We always sprayed the line if we were going to wet cut the slabs. The only way I can see removing lines in this instance is sand blasting. Maybe try some paint remover?

If it is iron oxide, then oxalic acid wood bleach should remove it.

Randy