Rust stains returning?

**Gary Odum** · 07-20-2010, 08:49 PM

A home owner parked a work truck on this concrete and it left some rust stains. I cleaned the driveway and applied oxolic acid at 16 oz per gallon and the stains were gone. Three days later the ho called me back and said that the rust had came back. I went back again and applied oxolic at 30 oz per gallon, the stains disappeared. 3 days later they're back.
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**Gary Odum** · 07-20-2010, 08:54 PM

This isn't my week for concrete. I also cleaned another driveway that had no stains, but the concrete was about 10 yrs old and looked bad beside some new concrete that had been poured about 1 yr ago. After cleaning it I applied oxolic on the old concrete at 16 oz per gallon and it didn't match the new but looked a lot better. Today I get a call from the ho and he said that the concrete that had been treated with the acid had an orange tint. Has anyone seen this happen before and is there a fix? No pics yet.

**Guy B** · 07-20-2010, 09:01 PM

Hey Guys, Gary is a good friend of mine. I gave him some 5% HF and this stuff still won't come up, any ideas?????????

**JL Pressure** · 07-20-2010, 11:02 PM

Gary on the old Vs new, does the old have a lot of aggregate(Stone) showing ? Sometimes with stone showing it will look OK and then the Oxalic can tint it a little, it doesnt really work perfect with heavy aggregate concrete

The other metal ruststains can be difficult, I have only had great luck with Oxalic if its irrigation rust stains and even that will go back to being orange quick at times if the lawn has a bunch of tainted dirt, dirt soaked in irrigation rust, it just runs back onto the driveway

Sorry I cant help, are you sure the rust isnt bleeding up from under the concrete on those stains?

Good luck

**Gary Odum** · 07-21-2010, 12:26 AM

No, it's pretty smooth with no stone showing. I explained to the ho that the two would never match, but the acid would brighten the old some and it did. Now he said that it has turned to an orange color.

He has used city water and a sprinkler to water his lawn. These two areas are where he parked the truck and only started to appear after he started driving the work truck home for a few weeks. I feel comfrontable saying that it's coming from the truck and not bleeding up.

**John Orr** · 07-21-2010, 12:33 AM

There are two things - other than ghosts or competitors - that I know of that will make the stains reappear...the truck or bleach/chlorine being applied over the area where the rust used to be. I have removed rust from a dive, then ds'ed 12.5% and the rust reappeared.

As far as turning the drive orange, are you sure you didn't use muriatic? Strong acid will "burn" concrete. Prosoco's Sure Klean 800 or Ferrous stain remover will reverse the burn.

**Gary Odum** · 07-21-2010, 05:15 AM

Thanks guys!!!!
Wow it's 4am...I've got it bad, I go to sleep thinking pwing and wake up think pwing.
I used a strong house wash prior to cleaning the drive, but I'm sure that it rinsed well during cleaning. I didn't reapply any sh after cleaning. When I used the acid, the really dark spots of rust turned green, but it washed away. I think "that" was just a chemical reaction, because I've seen it before when removing irragation rust from vinyl.
Someone else suggested Sure Kleen 600. What's the difference between 600 and 800? (That's a loaded question.)

**Gary Odum** · 07-21-2010, 08:26 AM

I found the link to their product list with suggestions, specs, msds and more....Thanks
.http://www.prosoco.com/ProductList.asp

**John Orr** · 07-21-2010, 09:37 AM

Gary, I use the 600 to boost my oxalic. (Actually, I buy generic 600 from Northern Tool in 5 gal buckets. Delivered to the store, they run about $60 - WAY less than the real stuff and just as effective.)