Removing red chalk lines from concrete (2023 Update)

[clare]

It WAS washable. Just wrong definition of washable. You can wash it all you like, and it will not dissapear.

[RobertMacy]

maybe "Whink", a commerically available mild hyrdofluoric acid for removing rust stains

but wear gloves!!!

[Seymore4Head]

What about rust in your naval?

[DD]

I had red chalk stain in a kohler bathtub and tried everything to remove it. Then I read that the red chalk is made from rust properties or something like that so I used Ospho on the stain. It disappeared in seconds!!! I don't think you will be disappointed.

[Mr. Dan]

I just found out today how to remove red chalk. Never been treated concrete 4 months old. Framers used red chalk and we are going to seal for the finish floor. The answer C L R. Calcium lime rust remover. I used full strength with a disposable paint brush. Brushed it it for about 30 sec and it was gone! Rinsed with a wet rag and moved on.

[Tekkie®]

Mr. Dan posted for all of us...

Good post, I believe it was asked many times and no satisfactory answer was ever given.

[mowmow]

replying to Tekkie®, mowmow wrote: I've had great luck with IRON OUT. I mixed a couple of cups of it into a couple of gallons of warm water and used a stiff bristled brush on the end of a broom handle (Menards) to pre-soak the area. I then sprinkled the Iron Out directly on the chalk line (which had been there for two years now). After a few minutes, I used the brush to work the wet powder a bit. I then used the mix in the bucket to essentially rinse the area while not diluting it excessively. I again added the powder directly to the areas where red remained. After about an hour of repeating this process (an not much sweat) the lines were completely gone in most areas and mostly gone in the rest. Wish I would have done this years ago. I finished with a garden hose and "wet-broomed" all residue off of the drive - the red will reappear all-spread-out if you don't do this.

I'd be worried about CLR affecting the appearance of the concrete (concrete in my area is heavy in limestone. Maybe Iron Out would have similar concerns (I'm no chemist) but I can say with certainty that it had no ill effects on my drive and I've used it to remove rust marks in several places in my very large concrete drive. Almost TOO easy!

Finally, someone commented about people doing stupid things when they don't hire professionals. I can tell you that even the best make mistakes, and that is what happened in my case. I hired the best in the area, and one their newbies used red chalk and we scolded for it. It will happen again to somebody - even if they hire professionals.

[mowmow]

replying to Tekkie®, mowmow wrote: I've had great luck with IRON OUT. I mixed a couple of cups of it into a couple of gallons of warm water and used a stiff bristled brush on the end of a broom handle (Menards) to pre-soak the area. I then sprinkled the Iron Out directly on the chalk line (which had been there for two years now). After a few minutes, I used the brush to work the wet powder a bit. I then used the mix in the bucket to essentially rinse the area while not diluting it excessively. I again added the powder directly to the areas where red remained. After about an hour of repeating this process (an not much sweat) the lines were completely gone in most areas and mostly gone in the rest. Wish I would have done this years ago. I finished with a garden hose and "wet-broomed" all residue off of the drive - the red will reappear all-spread-out if you don't do this.

I'd be worried about CLR affecting the appearance of the concrete (concrete in my area is heavy in limestone. Maybe Iron Out would have similar concerns (I'm no chemist) but I can say with certainty that it had no ill effects on my drive and I've used it to remove rust marks in several places in my very large concrete drive. Almost TOO easy!

Finally, someone commented about people doing stupid things when they don't hire professionals. I can tell you that even the best make mistakes, and that is what happened in my case. I hired the best in the area, and one their newbies used red chalk and we scolded for it. It will happen again to somebody

- even if they hire professionals.

[greendean]

replying to mowmow, greendean wrote: Thank you for your answer. Yes, even the so-called pros "goof' it sometimes. I have a red chalk line on my patio that was put there by the 'Pro' 6-7 years ago. My spouse finally is very tired of it, so I appreciate all the answers given here.

[Nicholas R Newton-Cahoon]

replying to DD_BobK, Nicholas R Newton-Cahoon wrote: Use a can of monster energy drink and scotch bright to remove lines

[headdown]

Unfortunately, I tried CLR on granite slabs with red chalk and it did nothing to remove or even fade it.

[micky]

I would just wait, or maybe use a garden hose.

I've seen plenty of chalk on sidewalks over the years, mostly to play hopscotch, or as modern art. And none of it lasts forever, or even 6 or 3 months. It must be time, and maybe the rain. Maybe the sun. If the sun has anything to do with it, red will disappear the fastest. I used to keep a map of NYC on my dashboard and after a year, the green and black streets still looked like new, and I think all the other colors were there and looked good, but the red streets had totally disappeared. Now ink and chalk are not the same, but the red is the one that disappeared.

[hubops]

A strong water jet can do wonders :

... not a power washer by any means .. but .. it's made in USA it's brass it's cheap.

John T.

[micky]

Yeah, good. I have one of those things but I can't find it. so I think I bought a plastic one because it would be elitist to have two brass ones.

[Ron Snyder]

Red chalk will NOT was off. Any contractor that tells you otherwise isn't worth what they are paid. It is why they also make blue chalk.

[mowmow]

Ron - I beg to differ, though I am not a contractor. I looked at the line in my new driveway (see my earlier post in this thread) every day for over a year before trying the solution in my posting. My reason for trying the Iron Out was that maybe red chalk uses iron oxide as a pigment.

As a follow-up, there is ZERO visible evidence that the line was ever there. I suspect some may have different luck based on whether and how their driveway was sealed. Mine was sealed before chalking (which should be the norm, as most sealers also help with curing), and I used V-Seal 102 sealer. This sealer is a non-glossy sealer, however, so I would think it is LESS favorable to removing the red stains. Nevertheless, it worked.