[quote=“Racer, post:18, topic:29805”]
hit it with the nmd80 It will also get rid of the mud stains from people tracking on it
[/quote] Hey I have this unusual job on a high end estate that has thousands of square feet of limestone and I’m at a loss as to what to use to remove the stain. Basically the landscape team attempted to stain it using a fertilizer based “mud stain” on it. But what happened is it turned the limestone all chalky and the white mortar brown. They pressure washed it themselves and managed to get most of it off except for several hundred square feet that is covered by an overhang. My guess is the uv from the sun broke down the rest of it pretty good so was easier remove. I did a test area and tried to remove the rest of the stain and brown marks from the grout using the following methods:
Hot pressure wash with 2500 psi. One restore, ebc and of course 4%sh (I figured it was organic so gave it a shot). The brown definitely isn’t coming off the white grout with any of that and it looks like the stain (slight discoloration) is holding tight as well. Do you think nmd80 would do the trick? The mortar is what it is but the limestone is what I’m trying to get clean/stripped. They will paint the mortar to remedy. If nmd80 would work can I do just the affected areas or do I need to treat all of the stone with it? I’ve never seen anyone stain limestone (or any surface for that matter) with a “fertilizer mud stain”. I’ve also never used nmd80 either. Here are some pics.
Won’t hurt to try it. Just follow directions. Easy. Plenty of videos on using.
Got the same cart too if you look in pics above. Kind of a pain to carry for small jobs though. Great for larger jobs. Get one of those screw on lids and drill hole in it so stuff doesn’t slosh out. Take you 12v and zip tie to sidewall to get out of the way. Piece of 2*4 for wheel chock.
Any good paint store will have though a lot only have the small ones. Took me about 3 stores to find locally. Let your fingers do the walking. Don’t really need unless doing tile like products.
Personally, I would wand it with a Soft Wash tip…
Thanks for all the great advice Rick.
This post keeps on giving. I need some more help…
I have customer with a flagstone patio that was poorly installed. The flagstone is quite brittle, and the installer did not sweep off the polymeric sand before activating. The polymeric sand in the joints is also too soft and eroding.
The customer wants the polymeric sand removed from the stone, but I would say it’s more than haze at this pint. There are areas of hardened polymeric sand that are about a year old.
You mentioned NMD80. Do you think that would help here?
I read hot water would loosen the polymers. Not much luck. Tried F9 efflo, not much luck. High pressure chips up big flakes of flagstone or sand in the joints, so that’s no good. I’m out of ideas for removing the sand from the stone without removing it from the joints or damaging the stone.
Hot water pressure wash or steam. You might have luck with a heavy duty stripper or Prosoco Dicone product. I haven’t tried either for polymer removal. I’d imagine the floor was damp when they were brushing in the poly sand or it started raining and/or they didn’t use a blower to properly remove excess before wetting.
It does great for removing the haze. That’s 75% of what I use it for.
I was pressure washing with about 200 degree water, but the thicker spots wouldn’t budge. The pressure also ended up flaking off the flagstone so I stopped using it.
I’ll look into a stripper/ prosoco. The bummer is this stuff is all over the patio. I don’t see a way to apply the stripper without hitting the joints which are already weak.
Does haze include full on hardened sand? I’ve pictured haze as leftover dust that reacted.
Typically haze is the leftover dust, but often has a little sand in it. I mean if they don’t blow it right, then little bit of everything left. But a couple coats of nmd80 and then surface clean lightly, doesn’t need to be hot, should do it… Think about what a mortar smear or tag is on a brick wall.
Thanks for your help everyone. I was able to find NMD 80 locally, so I’ll be trying thay tomorrow. I’ve been having trouble finding one restore or the right prosoco products.
Im worried about the NMD 80 going after the sand in the joints that are already weak, but hopefully not.
Never had any problem with that. If you’re sealing and you have weak joint sand, make sure you use a joint stabilizing sealer. That’ll help it.
Bad news. Tried out the NMD 80 today on a test spot, and overall it seemed to go well. Decided to complete the rest of it. Unfortunately it did not go well when applied to evething. A lot of the sand came out of the joints, and we ended up torching the grass. Just a bit of insult to injury there. We didn’t pre soak sufficiently, and I just learned it is pretty new grass.
Needless to say, the customer is upset. I will be re-sanding ASAP, that is if they let me. Any tips on getting the old sand out would be appreciated (the parts that are hard anyway).
Went back tonight for the final recon. Things kept getting worse. A few of the stones turned green. Is this repairable?
I used the EC Jet from echo Chem which is supposed to draw at 4:1. Applied two coats, about six minute dwell times, surface cleaned hot water. I have a bad feeling the ec jet was pulling a lot more than 4:1. It did smell quite strong.
Could be vanadium staining? A strong acid could do that to some masonry surfaces…
Do you have a picture of it before you applied?
Any thoughts on method 2 of cleaning vanadium staining?
Make up a solution of 100gm/litre of sodium hydroxide (caustic soda) and liberally brush on the stains. Wash off after three days with clean water. If the vanadium stains are a result of a previous treatment with hydrochloric acid, increase the solution to 200gm/litre.
Is @CaCO3Girl still with us?
Try a 50/50 solution of 12.5% sh, be sure to remover all organics first… rinse out the solution really good & let the surface dry… if there’s no change, now try sure kleen 800, it’s slightly milder acid…I think it’s a combo with sulfuric acid but it’s supposed to remove vanadium surface stains.
Thank you sir. Rough day today. If this will clean the green stains, at least I will have a complete plan for fixing this patio. I’ll let you know how it goes.
