A mixture of fresh, clean water and mild, all-purpose detergent, along with clean rags, is enough to remove dirt and any other buildup that you may have acquired while out on the water. I was under the impression it only converted rust and didn’t remove it but either the higher strength or the steel type used for the stampings (leaded?) had some effect on the rust removal. When I took it out I dragged the bolt through a snow pile to remove any excess acid and then brought it into the house and rinsed it off. Sand paper and steel wool will also remove rust, but they don’t get into tiny crevices. Also visible is the vast area of anode made up of four plates electrically connected together, and despite being in use at the time the photo was taken, the electrolyte is still clear with very few bubbles being produced.
It is a well known fact that phosphoric acid in vTirious forms and solutions has been found to be an excellent rust proofing agent. It immediately attacks rust all the way down to the bottom of rust pits and will leave the good metal alone, but will eventually start attacking it after several days, but the rust will be gone way before then and the part will be clean, rust free and ready to prime. If you do it correctly, bubbles will begin to form on the part and after a while the rust will begin to collect on the positive charged metal.
Though the fact Cola is often used to clean rust that just makes me want to drink it even less. Most acids will etch metal whether they cause rust or remove it. Phosphoric acid (H3PO4) is one type of acid which removes rust by converting it (iron III oxide) to a form which can be dissolved in water. On a smaller note, even if your surface doesn’t seem to have loose rust and you want to risk eating contaminated food, rusty metal doesn’t conduct heat as efficiently or evenly, so a rusty grill may not even function well as a reliable cooking tool. I tried using a baking soda solution to neutralize the acid but it left a film on the parts.
To get into small areas, use a mouse” sander or an oscillating tool with a carbide rasp or sanding pad attachment. Normally I use 5% strength distilled white vinegar (10% when I can find it,) mixed with equal parts or less tap water. Using citric acid has two effects, it has a low pH (high acidity) but also a complex forming activity with iron. Citric acid powder dissolved in water and even concentrated lemon juice will also remove rust in much the same way as vinegar.
Other phosphoric acid products like DuPont’s 5717S Metal Prep or MetalPrep 579 will remove light rust and prevent its return for a short time. On top of that, it’s pretty well known hydrochloric acid is a strong acid and phosphoric acid is a weak acid. As the rust forms, the surface of the iron is eaten away and converted into rust, sometimes evenly, but often deep local pitting occurs beneath wart-like protuberances. Before even attempting to apply the rust dissolver I sanded as much of the panel right down to shiny bare metal as I could using a DA and by hand.
If you plan to use heat to remove a fastener, be sure to first wipe off any lubricant or cutting oil you may have applied because the combination can cause a fire. Use a Scotch Brite pad to remove any sludge on the object and a bristle brush to clean those harder to reach spots. It is used as a cleaner by construction trades to remove mineral deposits, cementitious smears, and hard water stains.
Using the phosphoric acid was a final ‘belt and braces’ to convert the new flash rust and (in theory at least) some of the other black oxides to phosphate, essentially to give the acid etch a flying start. The amount of wait time necessary to remove the rust depends on the item in question, how badly it is rusted, and how well the store bought product works. The frame or fork must be electrically conductive – metal – but heat-resistant filler compounds can conceal rust pits, ugly welds and the like. Car makers treat their body shells before painting by spraying them with a form of phosphoric acid, which is then thoroughly rinsed off.
My last tank, a genuine un-restored 60 year old Norton tank cleaned up so well I am very tempted to just stop at this point and use it without further sealing protection but I’ll have to see and decide later. Baking soda and vinegar are two of the most environmentally friendly ways of cleaning rust from grills and any other metal objects. Look into electrolysis, it’s a process of removing rust using electric current.
Automotive rust needs to be identified whether it is surface rust or a deeper corrosion, this will dictate where to apply, front and back, how much how many times application is needed, and what sealent to use. In addition to phosphoric acid, another chemical that is used to remove rust is hydrochloric acid, sometimes called muriatic acid. However, they all prevent rust by keeping air and water off of the metal surface.
The electrolytic method removes only the oxygen from the oxidized metal by returning surface rust to metallic iron, rust scale is loosened and can be easily removed. The cost of rust is huge; America’s bridges alone need $76 billion worth of repairs , and much of that is due to rust. Take my word for it, if you use phosphoric acid, you’ll eventually wind up with more rust than you started with. I m’ suprised that people still do not make difference between phosphate, phosphoric acid and phosphorus !!
BTW – you can leave the part in Evapo-Rust for a week if you forget since it won’t harm the base metal, just the rust. Rust is common in the bottom-bracket and chainstay area, or wherever paint is damaged – also, due to sweat, on the top side of the top tube if a bicycle has been used on an indoor trainer. Roger is right, if the rust isn’t too heavy wire brushing should also work, but I prefer using a DA. Roger also mentioned it can take quite a few applications to get it all. Yep, hydrogen embrittlement, can occur with plating and acid treatments, but it’s mainly a problem with high-carbon alloy steels – not a worry with cast iron.
It is one of the objects-0f my invention, therefore, to add to a solution of phosphoric acid a quantity of some reducing agent sufficient to hasten the action of the solution upon the rust. RUST/ SCALE REMOVER – Use at a dilution of 5 to 25% (1 part in 20 to 1 in 4 with water)Depending on the amount of rust/scale to be removed. Now use electrical tape to tape the wired end and the other end thickly so there is no possible way you can ground out on the edge. Without all the rust dust, visibility will be much improved in your bead blasting cabinet. This works very well with hood hinges because it’s really the only way to clean the rust.