Bead Blast Rust or Use Rust Converter?

I have used both methods and it depends on what you are planning to do.

Blasting requires immediate preparation and at the least priming or the metal will have surface rust again in a couple of days. I found even overnight I had surface rust on components after blasting.

When I resprayed my car (bare metal respray) I used rust converter on surface rust. It turns it black and provides a protective layer to prevent further rusting.

I have also oil dipped metal to prevent rust. I did this on my surface plate feet. Heat them before dull red and plunge into an oil bath. Just be careful as the oil can sometimes flash, and you will lose an eyebrow, (don't ask how I know that)..........

So I don't bead blast or convert in normal circumstances. I use a wire wheel with long wires. Yes, some of them break off, but they are really easy to see and remove. Only for spot application I use rustoleum.

On things like small parts, I usually glass bead - unless they are fragile then I use a citrus based rust remover.

Like anything, the answer is usually 'it depends'

It all depends on whether you are trying to convert the rust or remove the rust. The Rustoleum product you linked is a rust converter. It simply converts iron oxide to iron tannate. Ospho is a product I have used that converts rust into iron phosphate. For rust removal, I've had great luck with Evaporust. Another method is electrolisis, but it won't get into cavities and corners unless they are line-of-sight with the anode and electrode.

vocatexas said:

Another method is electrolisis, but it won't get into cavities and corners unless they are line-of-sight with the anode and electrode.

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Not trying to be contrary but I've been using electrolysis for maybe 15 years or more and have not found this line of sight thing to be true. I've seen it said before but have not found it to be the case. Maybe I'm doing it wrong.

Though many of my machines were purchased used, some ancient and very well used, I avoid anything so rusty it requires sandblasting (ugh!).

Heavily rusted flat surfaces, such as you might find on a table saw or shaper top, can be restored by first scraping with a razor scraper, then steel wool, and lastly Scotchbright pads for metal (brown). Lightly rusted surfaces, such as engraved machine dials, can be cleaned up using just the Scotchbright pad.

mikey said:

Not trying to be contrary but I've been using electrolysis for maybe 15 years or more and have not found this line of sight thing to be true. I've seen it said before but have not found it to be the case. Maybe I'm doing it wrong.

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I have never used electrolysis, but watching YouTube videos about using it makes it seem to be a really useful choice for removing rust without damaging what metal remains. It is definitely something to consider for bigger jobs. You can make a tank out of wood or metal, or a hole in the ground, or an above ground swimming pool, or whatever, line it with polyethylene sheet, and get it working. The bath can actually be built right around the piece to be treated, as long as it will hold water. The process is not particularly dangerous to the user or to the environment, beyond what was in and on the metal. It is cheap, only a tank, water, washing soda, electricity, and a battery charger and some electrodes.

I really like Evaporust, but it is pretty much constrained to smaller and more important parts, due to the cost of the product. They really need to be totally covered with Evaporust, or an etched line will form on the metal at the liquid to air interface. The instructions say that wet towels can be soaked in Evaporust for using on larger surfaces, and perhaps that is so, but I have had no luck with it. Perhaps if you kept everything wet for the entire period by wrapping it with plastic wrap, or some other strategy besides re-wetting the towels often for the many hours needed for Evaporust to do the job. If I ever need to remove rust from a large but special part, I will use electrolysis. Both of those methods, done right, remove rust, and only rust, relatively quickly and without damaging the remaining parent metal. Zero etching or pitting.

Another method that is also safe is using molasses. It works, is environmentally safe, can be bought fairly cheap in large quantities at a feed store, and does the job without attacking the parent metal. The biggest issue with it is that it is as slow as... molasses! If you have lots of time, it is said to be a good choice. I have zero experience with it.

I will not use acids and other products that remove metal indiscriminately, unless perhaps it is an old rusty shovel. But, I don't let my shovels rust... I do not like the frosting that acids impart on the surface of the metal from attacking it along with the rust. YMMV.

I'm 2 steps below a novice machinist so I can't contribute much toward that end, but I've been operating and maintaining rusty old junk machinery as a logger, farmer, railroader most of my life.
The last 35 years I've lived here in Southeast Alaska and maintained equipment operated in salt water and high humidity (at least it's cool unlike coastal Texas or Florida ). Commercial fishing boats, sport boats, airplanes and vehicles are all subject to some pretty severe corrosion, everything is in a hurry to return to it's natural state. I've used just about every method available to clean-up rust; hand tools, power tools, wire brushes, grinders, needle scalers, elbow grease and chemicals. I like sand blasting, I just bought a new sand blast cabinet and I have a pressure pot for big stuff, for heavy rust on heavy iron it's fun to watch new shinny metal appear.
Several years ago I was restoring a old Dodge Power Wagon. Sand blasting tended to destroy sheet metal parts, it erodes away the thin metal but also causes it to stretch and distort. I learned about electrolysis. What a wonderful way to clean up rusty parts. I cleaned up some sheet metal parts that I thought were beyond salvage, sandblasting, wire brushing or chemicals would have destroyed them. After a dip in the electrolysis tank they looked almost new, you could even see the stamped part numbers.
I expanded to a 30 gallon plastic garbage can and a larger battery charger and started doing all the steel parts that way. I tried different electrolyte mixes ( plain water is an electrolyte, additives just make it more efficient) and discovered salt water worked best, I just go down to a dock and fill up buckets with salt water( I wash after in muratic acid then water and paint immediately). Any dc voltage will work, but the more current the faster the results. My 24 volt battery charger worked great until the smoke leaked out of it. The sludge that comes of the part and the anode build up in the bottom of the tank and when it reaches the part it creates a short circuit and out goes the smoke.
I had a batch going one time and was doing some oxy/ac cutting. I kept hearing loud pops, almost like a firecracker. I realized the sparks from the cutting were igniting the hydrogen gas bubbles escaping from the electrolysis tank. I was outdoors so there was no danger of hydrogen accumulating and causing a fire or explosion, but it's something to be aware of.
I got a 20amp 12volt power supply and a large fish tote from a local fish cannery to clean the larger parts from these old trucks, but life has put that project on hold for a while and I've only done a few small parts lately. Most of the work I've been doing lately is on small airplanes and electrolysis doesn't work on aluminum.

I hate seeing smoke from machines, it's like herding cats, you can never get it to go where you want, and it won't go back to where it came from.

I'm a big fan of electrolysis. I use washing soda (available at most grocery stores in a yellow Arm & Hammer Box, typically near laundry detergent). I have two different containers and power supplies. The small container is a 5 gallon bucket. The large is a big plastic trash barrel. One power supply is an old battery charger, the other uses a transformer salvaged from a computer UPS and a full wave bridge rectifier (about $3) and a fuse in case of accidental short. . It also has an ammeter to see how well things are going but it is not necessary, bubbles tell you if it's going.

Here are instructions for the process. Hooking the correct lead (Negative) to the part to be cleaned is important.

http://antique-engines.com/electrol.asp

On larger parts, I use the electrolytic process. I've done parts from screws to entire lawn mower chassis with this process. It removes all rust and paint, thereby saving a ton of work. It is pretty safe and mostly non-toxic. If I could only do one thing to remove rust, this would be it.

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Ditto. Washing soda in a paint bucket using rebar and a $15 battery charger I got at tractor supply. There's a good Instructable on this. People are freaked out by the dodgy-looking wiring, but the amperage is so low that even if you get a spark it's pretty harmless. Just don't use near any pools of gasoline.

For machinery I have a multi-stage process which escalates depending on how bad the rust is. Obviously first pass is kerosene and a brush, though it is slow going for anything but surface rust. Most of the time, the rust is due to accumulation of dirt/dust/etc in caked-on oil (undoubtedly used forty-weight), and brushing or spraying something that breaks up oil deposits like MMO or Heet then letting it soak for a few hours will make it possible to scrub off with a nylon brush, 0000 steel wool, or a brass brush (try them in that order). If that doesn't work, it's time for the heavy artillery, i.e. the expensive chemicals. Evap-o-rust, Corrosion X, etc. I've found USA Fluid to be quite effective if left alone for awhile, but it is rather over-priced and I have yet to locate an MSDS for it.

I only use a wire wheel for stock now - electrolysis is less of a mess (in terms of stuff flying around) and gets into all the nooks and crannies that a wheel will miss.

The Rustoleum Rust Reformer stuff is pretty good. I don't trust it yet, so I only have used it on things like metal carts, benches, and stands, but it seems to work pretty good. Get the caked-on rust off with a wire brush and kero, then do 2-3 coats and it looks good as new. Have to wait and see if it falls apart in ten years.