My understanding of epoxy coating is that it should be applied immediately to freshly blasted iron. Incidentally do all this outdoors well away from any metal tools, structures etc because the vapors can rust steel items that are some meters away! Use an electric drill fitted with a sanding disc or a flap wheel to cut away the surface rust. Also, if you forget about the acid bath and leave the parts in for too long, (more than a week) they get heavily sulphated, as the sulphuric acid forms a white sulphate layer on the parts been cleaned, which is a nightmare to remove by wire wheel or by sand paper. I bought straight 80% phosphoric from the local cleaning chemical shop cheaper than the 30% strength rust converter to use on a 1970’s vintage sheet steel spark plug blaster.
Rust Encapsulator is dry to the touch in 1-1/2 to 2 hours, and is thoroughly dry in about 4 hours at 68°F. Allow the naval jelly to sit on the surface for up to 20 minutes, depending on the amount of rust to be removed. In my various electrolysis work my rust got removed from the item and suspended into the electrolyte or attached to the anode. Boeshield Rust-Free Spray , a strong acidic rust remover, is a great way to remove that rust quickly. This means that you can leave metal in Phosphoric Acid for much longer than necessary with very little damage.
Many electrolysis instructions will tell you that the process is line-of-sight.” That is, rust will only be removed from the side of your part that faces the waste electrode. No go on muriatic, vinegar was far too slow, & both of those flash rust A LOT very immediately. Rust arises from the surface oxidation of iron or steel in the presence of atmospheric oxygen and moisture.
I’ve always been fascinated with letting the chemicals do the work instead of all that grinding and wheeling and blasting to remove rust! FrankR, I don’t know if this will help, but my whole body was (and some still is) covered in the kind of rust you are dealing with on your hood, maybe even worse. Most everything we use comes from the ground in an impure state, and the impurities have to be removed. Phosphoric Acid has a clear viscous appearance, pH less than 1.0, density of about 1.67 kg/l, and a minimum of 1410 g/l phosphoric acid by titration or 85%w/w. Grapefruit: Remove limescale by cutting the grapefruit in half and sprinkling one half with salt.
Sand blasting is the way I like to clean/remove rust from parts, surface is ready for paint or plating after a good blow off with clean air from the air hose. I use breath masks all the time when spray painting (and did when mixing herbicides), so that is not a problem either. Depending on how I want the surface to look (patina or not) will dictate the product I use to do the final surface cleaning/polishing.
I did enjoy the article, though, because I’m sort of a mad scientist at heart and will probably try that process just for the heck of it, just as I have with citric acid for rust removal. This is perhaps the most basic of methods, simply scraping by various means to remove the rust. I let the parts lay in the acid for the number of days that is required for the rust to be dissolved. There will be times when you can’t use it. It sometimes won’t touch the skin” on some castings. I don’t see a problem with removing rust from stressed parts- but if they are damaged by rust they remain damaged and weaker.
If I had a vise such as the OP, dropping it into a gallon or more of dilute solution overnight would leave the rust as a nice patina which can be wiped or wire-brushed off. For areas where you can’t readily reach to remove with Fast Etch, use Eastwood Rust Converter on heavy, scaly rust, followed by Eastwood Rust Encapsulator If the area is not heavy and scaly rust, use Eastwood Rust Encapsulator. There are many commercial products that claim to displace moisture and prevent rust.
And at the same time rust proof the metal and then rinsing the metal with a solutio of sodium phosphate. NOTE: you can use a section of chain, tied off w/ fishing line to mostly eliminate the issue of getting all the nuts and bolts out. Although not as strong as phosphoric acid, hydrochloric acid can be used on most any surface without risking acid damage. Keep your metallic stuff slightly lubricated, and store away the stuff you don’t use often in a dry place, maybe in ziploc bags with a bit of machine oil on ’em. Make sure you have a mask on, as little rust particles floated off and became breathable.