Removing red chalk lines from concrete

Do you mean chalk...... like chalkline chalk?

If so, ignore it. It will wear off in time. I believe there is a high potential for doing permanent damage to your "green slab", let it cure.

cheers Bob

Yes Bob, chalk line chalk. Thanks for you input.

I got the 'bright idea' to use a chalk line when I was hanging wallpaper. Some red chalk got the wallpaper and nothing would remove it. Been there for 12 years now. Yeah, I know that didn't answer your question but thought I'd share the experience anyway.

He already did permanent damage by putting bleach on 3 day old concrete. The surface will probably deteriorate and flake off where the bleach was used.

The best solution at this point would be to rip it up and pour new concrete.

This is proof how amateurs can destroy something in seconds by doing something stupid. That chalk was hurting nothing and would have vanished in a short time just from rain and normal use. Now the whole job is ruined permanently. Even if the surface does not crack off, that bleach will show up years from now when the chalk was only a memory.

As Bob F posted, if depending on the type of chalk it was, the marking could be there a LONG time.

scroll down & checkout page 48

unfortunately, it looks like the "red chalks" are the longest lived ones. :( My suggestion remains the same, leave it alone and it will eventually fade.

cheers Bob

The red chalks will last and last and last and... The OP should practice ignoring the chalk lines immediately if not sooner. Otherwise start considering Plan Bs - masking.

I suspect it bothers OP more than anyone else that sees it, especially since everyone else will assume it just happened. I wonder if rubbing in a poultice of the dye (in some shade of gray) used for tinting concrete or grout, or even plain old cement dust or powder, would take the edge off, or just make it worse? (not advocating it, just curious)

But I mostly agree with the others- sunlight and weather and time, maybe lots of time, are likely the only real cure at this point.

I tried it in a small inconspicuous spot and rinsed it well. If there is some damage how long before it shows?

You could try one of those powerful laser pointers. There are some that will burn paper but I'm not sure how much money you would like to spend on a new toy that could have any number of unexpected uses. ^_^

TDD

Paint it with cement.

simple,Green scouring pad and a little water if it takes more than that th en use a 120 grit Sandpaper these are stains they don't just magically disa ppear I've snapped lines that were bogus and tried to cleaning them off min utes later and they were extremely hard unless you have a little water and Green scouring pad it works like 400 grit sandpaper and if its been in ther e for a long time you may need to go a little more aggressive with sand pap er yeah that takes some elbow grease it's a stain most times when you snap lines on a slab you want them to be permanentbecause they're usually being covered up by framing

Isn't chalk a calcium based compound, therefore a 'fast' wash with muriatic acid [too fast to eat the concrete] remove it a bit better?

Coloured "chalk" isn't "shalk" I think some of it is more closely related to laser printer toner!!!

I'd try vinegar to dissolve the chalk followed by a quick pail of water to wash away the pigment.

I still have some red chalk lines that have survived dozens of pressure cleaning and 2 hurricanes. Red is pretty permanent.

I once spilled large drops of 'washable' red food coloring on the zipper front of a pair of white dress trousers. You guessed it. Washable indeed! Instant 'painting clothes'

They had to use that carcinogenic red food coloring somewhere! ;)

Seriously, the "red" seems to come from iron oxide according to the MSDS so barkeepers friend, naval jelly or some other rust remover might work.

Get som "barkeepers friend" - apply in a thick paste and cover to keep it from drying out. Leave it for an hour or so and scrub with a stiff bristle brush.

That said, a shotgun could prevent having to do it again. Shoot anyone using red chalk. There is no excuse for using that crap when blue works just as well and is a LOT easier to remove!!!