how to remove fertilizer iron stains from fence

How to Remove Fertilizer Iron Stains

Removing Fertilizer Iron Stains from Outdoor Surfaces?

Iron is a great mineral element for achieving a deep, dark-green lawn. Unfortunately, when iron is oxidized from its reduced form (Fe(II) to Fe(III)) some unsightly red/orange staining can go along with it. This is a common problem associated with iron-containing fertilizers or well water. So in your quest for a healthy, green lawn, you accidentally sprayed some iron-containing Simple Lawn Solutions product on your fence, home siding, or deck. Maybe your well water irrigation has made contact with some concrete in your yard. Fear not, in this article we will discuss what to do next and how to return your exterior surfaces to their original selves.

First Things First

man spraying hose-end sprayer of fertilizer

Always keep in mind, that when applying fertilizer with a Simple Lawn Solutions ready-to-use applicator, you have the option to switch from a stream of “water and product combined”, to a stream of “water only”. If you catch your misapplication fast enough, simply move your switch on the applicator to “water only” and try your best to wash the surface of the product, as quickly as possible, before it has the chance to absorb and set in. If you were applying your product with a pump sprayer or weren’t able to run to the hose quickly enough before the product set on the surface, we’re going to explore a few options at your disposal for removing these stains.

Before we move into talking about specific products or methods, let’s go over a few key fundamentals. 

  1. Please always consult the product label for directions, safe surfaces, and any safety precautions you should take when handling products. A lot of rust removers are powered by acids which can burn your skin if proper precautions are not taken. 
    sprayer bottle with cleaner
  2. Always test products in an inconspicuous area before slathering them all over, in case the product and your surface of interest have compatibility issues. 
  3. Remember, what works for someone somewhere on some surface, may not work for the next person somewhere else. Trial and error is the best method here. Test different products or methods of removal to figure out what works best for your specific situation. 
  4. Also, if you have any surfaces with desirable iron-oxide pigments, staining, or coloring, take care to not apply these products to those surfaces, as these products will not discriminate between iron sources. 

With that being said, here are some common products or active ingredients that you can try when a misapplication of an iron-containing fertilizer has occurred. 

Products and Active Ingredients  

Iron OUT and Iron OUT Outdoor 

Iron OUT is best to be used on: siding, driveways, exterior walls, fences, decks, docks, patios, boats, stucco, masonry, wood, fiberglass, metal, sidewalks, and foundations.

Both products contain fluorosilicic acid and oxalic acid. It appears that the outdoor version is simply a liquid version of the Iron OUT powder. The powdered version is designed to be mixed with water, while the outdoor version is a liquid, designed to be applied directly to the stain. Oxalic acid is known as an extremely versatile iron stain remover. Instructions for application to siding, driveways, exterior walls, fences, decks, docks, patios, boats, stucco, masonry, wood, fiberglass, metal, sidewalks, and foundations are included on the label.

Goof Off (RustAid Outdoor) 

Goof Off is best to be used on: concrete, stucco, wood, fiberglass, brick, painted surfaces, and vinyl siding.

Powered by hydrofluoric acid and oxalic acid, RustAid is labeled for use on concrete, stucco, wood, fiberglass, brick, painted surfaces, and vinyl siding. The diversity of surfaces to which this can be applied makes it almost mandatory to at least try. This product has great reviews and comes from a reputable company with a great reputation. The label states that it is safe for plants and grass but to spray surrounding plants or grass with water prior to use. This product also is designed to be applied full-strength, so no dilution will be necessary. Goof Off claims that no rubbing or scrubbing is necessary, but we will let you be the judge of that. 

cleaning products

CLR (Calcium, Lime, and Rust Remover) 

CLR is best to be used on: porcelain, stainless steel, vinyl siding, concrete, brick, and stucco.

It is not recommended for: wood surfaces.

CLR is powered by lactic and gluconic acid, along with the surfactant lauramine oxide. This product is extremely versatile and has application instructions for porcelain, stainless steel, vinyl siding, concrete, brick, and stucco. CLR can be used alone or diluted with water. Make sure to rinse your CLR application at the 2-minute mark. This product is not designed to be left on surfaces for longer than 2 minutes. CLR does say not for use on wood, so if it’s a stained wooden fence that you’re looking to clear up, look into something different, possibly something containing oxalic acid, which we will discuss further down. This is a great place to start your iron stain removal journey. CLR is probably considered the mildest of all the products listed and can be a good place to start. If CLR doesn’t work to remove your iron stain, consider trying something a little stronger, like the products below. 

Oxalic Acid (Many different products) 

Oxalic Acid is best to be used on: wooden surfaces without paint or finishes.

This is the active ingredient commonly found in products labeled as wood bleach. Oxalic acid is pretty nasty stuff, so please follow the safety precautions listed on product labels. This is most likely your best option for iron stains in wood. If other products haven’t worked or aren’t labeled for use on wood, this is your best bet. Here is a nice resource with all you need to know about wood bleach. Please note that wood will need to be removed of paint or finishes prior to using oxalic acid.

rust on concrete

Singerman Laboratories Rust Remover for Concrete 

Singerman Laboratories is best to be used on: concrete.

This is a pretty specialized product labeled specifically for use on concrete surfaces. It’s a powdered product designed to be mixed with water to create a gel. The gel makes the product great for vertical surfaces where a liquid would just run down and away from the stain. The label also claims that it will not harm grass or vegetation. If you have iron stains on your concrete, this could be a great product for you.

It is our hope that one of these ideas above will be a simple solution for removing exterior iron stains, whatever the cause. Remember this may take some trial and error before you find the product that works best for your specific situation. Some iron stains will come off really easily, while others may take more effort. Stick with what works and may your iron stains be ever-soluble.



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