Rust Removal - Evapo-Rust? a concentrate? (not molasses or electrolysis)

[Doug Hobkirk]

I need to remove rust from a pile of stuff - a bunch of auger bits, several bench planes, a bunch of small foundry tools (for pattern-making in sand casts, I think is the correct phrasing), etc.

I've used Evapo-Rust in the past and thought it worked pretty well. But maybe there's something better, or a better approach. Here are some of my ideas (feel free to correct any wrong thinking):

1. Electrolysis seems like it's too complicated for my needs.
   
   1. I have battery chargers, buckets, rebar, etc. Making it wouldn't be hard (4 pieces of rebar spread around the outer edge). And it seems sort of cool, since I've never done it.
   2. But my projects are mostly small and many - maybe 200-300 mostly smallish pieces. Making a "rack" for housing 8-12 alligator clips and keeping the items from touching - it seems like a hassle.
   3. Do I need to remove the rust from the rebar after each batch?
   
   
2. Molasses? This was new to me, but apparently it works quite well. I assume my local feed store carries it.
   
   1. But it takes a LONG time - at least a week - and it stinks.
   
   
3. Evapo-Rust
   
   1. Dump some it an appropriate sized plastic bin, dump in rusty stuff, and wait an hour, or two, or overnight. Remove black slimey objects and hose off (or use sink)
   2. Spray w/ something or wax immediately so it doesn't start rusting immediately.
   
   
4. Concentrates are new to me, but several companies seem to advertise "we're as good as Evapo-Rust but our conentrate is cheaper!"
   
   1. Companies like Liquid Specialties, Espirit, Industrial Rust Eliminator

Cost

This is what I found last week. I was looking for the best price per gallon. I was thinking 2 gallons would probably do for my current projects, but 5 gallons might save money in the long run and I know I will need it again. All prices include shipping.

1. Evapo-Rust - $18/gal for 4 gal., so out-of-pocket = $72 (the best of the many packages I found at Amazon)
2. Conccentrate - 3 different products, but they all end up costing $10/gal. (after it's mixed w/ water), for 5 gallons, so O-of-P = $50
3. Molasses - FYI, it works out to under $1/gallon

What say you all?

Thanks

[Matt Day]

I don't have any experience with any if the ones you listed except Evapo-rust, but I love the stuff. Personally I wouldn't bother trying anything else since it works so good.

You do reuse the stuff after you use it right? After I use it on (mainly smaller jobs so far) I strain it through a blue shop towel to catch the solids and put it back in the jug.

[scott spencer]

Anyone have any guesses whether or not Evaporust would work for cleaning rust out of a motorcycle gas tank?

[Todd Burch]

Phosphoric acid - plain and simple. Cheap too. You can get it @ the borg or an auto parts / auto body store. I'm guessing here, but I suspect all the above, but perhaps not Molasses, are phosphoric acid based.

I used electrolysis a couple years ago. Worked like a charm. I was totally impressed. But dousing in phosphoric acid works just as well, and perhaps is even faster. The phosphoric acid will also leave a protective coat on your item to keep it from re-rusting until you get it coated.

I cleaned a large spring (1.5" in diameter x 15" long) in a piece of 2" PVC pipe with a cap on one end in just a few hours. The spring had about 50 years of gunk on it. I wire brushed it first on the outside and soaked it for a bit, then, I bought a refrigerator coil cleaning brush and cleaned the inside of the spring in intervals as I was going through the soaking process. After soak/brushing all day, it came out black and squeaky clean. I sprayed it with Fluid Film (available at John Deere tractor stores - GO BUY SOME!!) afterwords, and over the last year, it's still clean and rust free.

[peter gagliardi]

Powdered citric acid mixed with water is cheap, and works very well also. Just be sure to rinse off parts and dry to prevent a layer of flash rusting.

[Doug Hobkirk]

Phosphoric acid - plain and simple. Cheap too. You can get it @ the borg or an auto parts / auto body store. I'm guessing here, but I suspect all the above, but perhaps not Molasses, are phosphoric acid based.

Excellent. I think I remember Bob Smasler (sp?) said that in a long-ago post. The depot has 4 options when I search for "phosphoric acid":

1. Eagle Etch & Clean for Concrete - $13 for concentrate makes 5 gal = $2.60/gal
2. Klean-Strip Phosphoric Prep and Etch - $16/gal
3. Miracle Sealants Fast-Acting Phosphoric Acid Cleaner - $27/128 oz = $54/gal
4. Ready-Strip Rust Remover Spray - $9/qt = $36/gal

The first two seem dedicated to paint and/or concrete prep . The last two cost considerably more. Am I missing something?

[Todd Burch]

I use #2. (heavy concentration)

[John Huds0n]

Anyone have any guesses whether or not Evaporust would work for cleaning rust out of a motorcycle gas tank?

Another phosphoric acid user here

Actually I used "CLR" (Calcium Lime Rust) 3 or 4 years ago to clean out the tank on my motorcycle which had over 100k miles and was looking pretty nasty inside

Keep in mind that phosphoric acid actually changes the rust to ferric phosphate which helps prevent further rusting but it will probably discolor what you are using it on. Also consider 'naval jelly'

Before and after

mc tank before.jpgmc tank after.jpg

[Clay Fails]

I use wlectrolysis. Works great for my needs.

[scott spencer]

Another phosphoric acid user here

Actually I used "CLR" (Calcium Lime Rust) 3 or 4 years ago to clean out the tank on my motorcycle which had over 100k miles and was looking pretty nasty inside

Keep in mind that phosphoric acid actually changes the rust to ferric phosphate which helps prevent further rusting but it will probably discolor what you are using it on. Also consider 'naval jelly'

Before and after

mc tank before.jpgmc tank after.jpg

Thank you....

[Roy Turbett]

+1 on electrolosis and you don't need a bunch of alegator clips. I just suspend the parts from a single steel rod with stranded copper wire that I reuse and attach the negative to the bar. I also line the bucket with rolled steel flashing that I run a single bolt through to connect the positive terminal. I found that this works better than multiple pieces of rebar because the anode totally surrounds the piece(s). Some guys don't like to use galvanized flashing for the anode because they think it will coat the piece with zinc. This hasn't been a problem for me.

[Chuck Saunders]

Phosphoric acid - plain and simple. <edit> I'm guessing here, but I suspect all the above, but perhaps not Molasses, are phosphoric acid based.

Hi Todd,
Evapo-Rust is not phosphoric acid based. It works by chelation. non toxic, does not convert the rust like H3PO4 does. I don't know about the other concentrates as I have not seen them. I get Evapo-Rust in 5gal buckets from Northern Tool (shipped to store = free shipping)
Chuck