Iron stains from fertilizer

Discussion in 'Fertilizer Application' started by Spraytek, May 23, 2013.

  1. Spraytek

    Spraytek LawnSite Member
    Posts: 114

    During my last round of fertilizer applications I failed to blow off all of the granules of iron/fert and now I'm left with a nightmare to resolve. At two of jobs, I managed to stain their limestone pool surrounds. Luckily the stains are pretty localized, but they are BAD. I've tried rid-o-rust, lemon juice and a product called Lustro Italiano rust remover. Nothing has worked so far. Does anyone have a tried and true method? And let me go ahead and say I don't need a lecture on blowing off all of the surfaces. As I said earlier, I blew the surfaces, just missed a few spots. Thanks for your help.
    Posted via Mobile Device
     
  2. rlitman

    rlitman LawnSite Bronze Member
    Posts: 1,518

    You need an acid cleaner to get rid of the rust stains, but any acid will etch limestone.
    I would suggest you find an oxalic acid cleaner (often labeled "wood bleach"). Oxalic acid will be milder on the limestone than other acids, but attacks rust by turning it into a water soluble CLEAR chemical (iron oxalate) that will wash off.
     
  3. ted putnam

    ted putnam LawnSite Platinum Member
    Posts: 4,535

    I accidentally sprayed iron (lower dose) on a freshly installed fence. It turned the fence grey in less than a minute. I think I bought some of what you are talking about from the hardware store. It was called "Wood Brightener". It worked great(and fast) for what I used it for. I couldn't begin to tell you if it would work on cement or limestone though...
     
  4. greendoctor

    greendoctor LawnSite Fanatic
    Posts: 8,938

    Oxalic acid will work on concrete and stone. It is much better than muriatic acid. No fuming and way less etching. Plants and grass take it far better as well.
     
  5. RAlmaroad

    RAlmaroad LawnSite Silver Member
    from SC
    Posts: 2,174

    I have a couple of lawns that the wells used for irrigation have iron in the water. Sounds strange for a coastal community. At times the sprinkler heads will get hit by mowing guy, winds or for unknown reasons the water will hit the vinyl siding. After a while the rust stains start. I've used a product called "Rust Away" sold by gallons at Home De[ot. When spraying on the vinyl from a smaller spray bottle, the rust just goes away. The AI may be oxalic acid as Greendoctor said. It may work on the limestone as well. Worth a try as it's very inexpensive. Remember that limestone is calcium and is very soft which causes the stain to penetrate deeply and may take a few treatments rather than a prolonged abuse sorta like tattoo removal.
     
  6. Spraytek

    Spraytek LawnSite Member
    Posts: 114

    I've read on a few different sites that oxalis acid would work, but that it was extremely toxic. I'm assuming they meant the fumes. I think I'm going to try to find some. Did any of you who have used it have to scrub the stain? How long did you allow the product to sit before washing off?
    Thanks for the help.
    Posted via Mobile Device
     
  7. ted putnam

    ted putnam LawnSite Platinum Member
    Posts: 4,535

    On wood I used a brush to apply. It was mostly to apply evenly than to actually scrub. Scrubbing was not necessary. I tested a few out of sight spots first and determined that leaving it on there more than a minute(60 seconds) and it did too good of a job (if that makes sense) I had a charged water hose handy for quick rinse. stone/cement will surely take a little longer. I would do like I did and find an out of sight test spot if that's possible to experiment with initially. Sure hope it works for you. Good Luck.
     
  8. Ric

    Ric LawnSite Fanatic
    Posts: 11,946

    .

    Lesco has sold RUST ERASE for year. It is oxalic acid. Of course the great thing about oxalic acid is the minimal impact on soil and plants

    Paver's and other surfaces where I don't want to take a chance, I use Household Vinegar. From an experience on Black Top road I found oxalic acid clean TOO good and leaves a Clean spot that takes years to blend in. Yes it takes Multiply applications of vinegar which is a PITA, but having to replace a Paver Brick Driveway isn't cheap.

    Muriatic acid not only tears up surfaces, But it can sterile the Ground and kill plants and trees.

    .
     
  9. rlitman

    rlitman LawnSite Bronze Member
    Posts: 1,518

    No, the chemical. Don't eat it, and wear gloves. It isn't really that bad.
    Oxalic acid is the toxin in rhubarb. The "fumes" are just fine.

    Muriatic acid fumes are VERY bad, but muriatic acid will also etch stone pretty horribly. That's not necessarily a problem on concrete where it won't be noticed, but it is a problem for you.

    Vinegar is about as acidic as oxalic acid, but oxalic acid is stronger at removing rust (and oils as Ric discovered on asphalt) than vinegar. Vinegar should work as would CLR/Limeaway, which is phosphoric acid, but would be slower.
     
  10. Spraytek

    Spraytek LawnSite Member
    Posts: 114

    Picked up some absorbing acid today and getting the oxalic tomorrow. If that doesn't work, I guess I'll try vinegar. I'll let everyone know how it/they work. Thanks for all of the responses.
    Posted via Mobile Device
     

Share This Page