Proper Application of Chelant Based Rust Removers

  The time has come for new eco-friendly methods of rust removal. The most promising of which are the chelant type removers. Even though they have been around the better part of a decade, it is a very short time when one considers how long alternative methods have existed. Sanding, sandblasting, wire wheels, grinding and dangerous acids will always have their niche in rust and coating removal, but when only rust removal is required, non-hazardous removers are usually the best, safest option.

The purpose of this article is to discuss the proper application of these fluids. After several years as an end-user in my auto repair shop, I decided to become a distributor of one of these chelant–based removers. Over this time, I have had a great deal of success after learning all aspects of chelant type removers. First I will explain some benefits of these types of liquid rust removers.

Education is the key!

I’m not talking lengthy classes. Simply understanding how to apply these water-based, chelant-type removers by reading the following paragraphs, or a tutorial, will go a long way to ensure success.

There are two ways to remove rust from small or large objects. A dip or immerse method, where smaller objects are put into a container and covered with the fluid. In order to de-rust larger objects, a spray or recirculation method can be used. The fluid is simply pumped over the object, recaptured as it flows off, and is continually pumped back over the object.

Several factors contribute to successful application of the latest technology rust removers: cleanliness of the object to be de-rusted, type and cleanliness of the container used to dip the object, previous coatings, type of rust, time, temperature, hardness of steel and cast iron, mix ratio for concentrates, water hardness for concentrates. In order to optimize the effectiveness, one must take into consideration all of these factors. Occasionally I receive feedback about the fluid not performing correctly, and every time, one or more of these factors are ignored. This can result in a less than favorable experience on everyone’s part. 

First of all, cleanliness is paramount. If your rusted object is covered with grease, oil, dirt that can be cleaned off easily, or thick rust scale that can be knocked off with a hammer DO IT! This will prevent the chelant rust remover from having to do the job for you. It will deal with these things to a certain extent, but you are better off spending just a few cents on a good degreaser/cleaner.

If using the dip/immersion method, use either plastic or stainless steel containers, tanks or other vessels. Galvanized containers will not work since the fluid will remove the galvanized coating. Steel or cast iron containers should be avoided. They may already have contaminants, rust or other deposits that will shorten the life and effectiveness of the fluid.

One simple factor to consider is whether or not the object is partially or fully top coated. These removers will not remove any top coatings that I am currently aware of, only the rust. I did, however make the mistake of trying to remove the rust from a decorative steel lawn ornament for the purpose of experimentation. Unfortunately, this ornament was originally intended to look rusty. What I failed to realize was that it was also top coated with a clear finish, which simply looked like rust. Weeks later, a scratch in the clear finish allowed the fluid to enter; it began removing rust, and bubbled up the finish. Only then did I realize it was top coated. Always check to see if there is a clear finish!

The type of rust you are attempting to remove will determine if chelant-based removal is the best method. Red oxides, which are the most common forms of rust, will readily be removed. Black oxides, also a form of rust, is much harder than red oxide, and in some cases, may not be removed easily or may take much longer. Some ‘pure’ black oxides do seem to respond well.

Time is a factor; however it depends greatly on other factors to achieve the desired outcome. The longer an object is left in the solution, the more rust it will remove until the chemistry is used up.

Temperature plays a significant role and will change the time it takes to remove rust drastically. I cannot stress this enough. If you are not using these chelant-based removers in at least 60-70 degrees Fahrenheit, you will waste time! So often I hear that someone is de-rusting an object in a cold garage and they complain that it is not working. I understand how difficult it is sometimes, but try to avoid cold temps and get that fluid warmed up. You will see a marked increase in the speed of removal. Used judiciously, salamander type heaters can evenly heat large objects, or at least the general area. You will enjoy the warmth as well!

Once you are operating in a warmer environment, you will be surprised to see the removal speed increase. Do you want to it to go faster? Most of these fluids can be heated as high as 150 degrees Fahrenheit for even more significant time savings. Heating can be accomplished in a number of ways. I have personally done some household items and small tools on the kitchen stove using a candy thermometer (or similar) to monitor the temperature of the fluid. Larger objects can be immersed in a 5 gallon pail or larger vessel with an immersion heater. Immersion heaters come in all shapes and sizes. Many can be found in farm, tractor and hardware stores for the purpose of preventing watering troughs from freezing. Once again monitor the temperature. Heating above 150 F will not be beneficial.

Regarding the surface hardness of various steel and cast iron; the harder the surface, the harder the rust is, the longer it will take, period.

The following applies to concentrated removers only. I cannot stress the importance of mixing concentrates properly.

Mix ratio of concentrated types is extremely important. We all have, at one time or another believed the ‘more is better’ approach. Surprisingly, the concentrated versions of chelant-based rust removers simply will not work if used straight out of the bottle. These have to be mixed with water to activate the chelant chemical. The remover I carry is mixed 10% strength for light rust removal, and up to 20% for heavier rust.

The type of water used to mix with concentrates can have some impact on effectiveness of the fluid. If the end-users water is extremely ‘hard’, benefit will be realized by mixing with distilled or softened water. This is due to the chelant chemistry ‘grabbing and holding’ the dissolved minerals in the water and leaving less of the chelant to work on the rust.

Ultimately, your attention to these factors will make for an easy and effective experience. I would strongly urge you to contact your potential supplier to discuss your particular application. After all, they are there to assist you with your rust removal process. They want you to have the best experience possible!

For more rust removal information please view:  www.rustdepot.com

Email:  lee.johnson@rustdepot.com