Working on a rusty piece of farm equipment. Too big and awkward to sandblast.

In the past I have used wire brush to get off as much as possible followed by eastwwod rust encapsulator as a primer.

Any better methods or suggestions ?

Brush on some phosporic acid or Evaporust on the surface, then cover with a plastic sheet to keep from evaporating. Every few hours brush again and let it sit
over night. The rust will soon be dissolved.

I found that once that encapsulated paint has been applied it’s very hard to get down to the rust underneath again. Immersion in some type of fluid is the best option but depends on what you have available.

This is close to what I would do. But first, it sounds like the rust encapsulator isn't what you want to use on this job?. Your discussion would be interesting.

Farm equipment is usually a combination of cast iron and steel bar stock, each with a different surface, so you'll need to treat each differently. For example, you can use sandpaper to remove rust on bar stock, but not on castings.

First physically remove as much rust as possible with powered wire wheels or similar and hand wire brushing. Maybe some sandpaper, wet sanding, or filing as needed. Then clean well with soap and water or mineral spirits or both. Apply Evapo-Rust and keep the metal continuously damp by covering with rags or paper towels followed by covering with plastic to retard evaporation. Re-apply as needed starting in the morning and continuing for the rest of the day as needed. Of course, immersion is much better because this isn't the optimum way to use Evapo-Rust. In any case, the metal must be continuously wet and re-wetted, because small amounts of Evapo-Rust will soon be chemically depleted in the presence of rust and must be replaced with new liquid.

If all rust isn't gone, start over, finding better ways to keep the metal continuously wetted with Evapo-Rust. Inspect carefully, because red rust will be turned to black rust by the Evapo-Rust. Probe dark deposits with a file or similar.

While still wet with Evapo-Rust (re-wet if needed), wipe off, apply mineral spirits with a paint brush, and wipe off again.

Apply phosphoric acid (I use Rust Cure) with a latex paint brush because the acid will eat up natural bristles. Before it dries, wpe off, apply mineral spirits with a paint brush, and wipe off again. Phosphoric acid isn't very corrosive to skin, but follow all precautions like rubber or vinyl gloves and don't breathe fumes. Don't allow phosphoric acid to get on anything galvanized or zinc plated because it is much more active on zinc than iron or steel.

In rust pitted steel (not castings) there's the special case of rust still present in the bottoms of the pits as evidenced by dark spots in the centers of the pits. Wet with phosphoric acid and go over the area with a powered wire wheel turning slowly. Repeat until all dark spots are gone and all the area is metal colored.

The cheapest way I've found to get Evapo-Rust without paying shipping is to order 5-gallon buckets delivered to a Northern Tool store and pick up. Costs about $80.

An inexpensive phosphoric acid is Klean Strip® Phosphoric Prep & Etch. About $16.00 a gallon at Menards. I also use feed grade molasses from Tractor Supply where 1 gallon costs $10.00. One part molasses and eight to nine parts water will give you a 9 to 10 gallon rust removing solution. If you build a vat with lumber and a plastic liner (or buy a kiddie pool) you can have a 50 gallon solution for $50.00. How large are the parts?

too big and awkward to sandblast?

save the time and effort and just hire a portable blaster to come clean it up. sometimes its just more cost effective to have a pro come do work than dicking around spending the same amount on chemicals to do half a job. hire one of those dustless morons, they are so hungry to make they payments on their $60k rig they will work for almost nothing. lol

Thanks for ratio on molasses I have 8x8x4 vat I’ll put about 125-200 gallons in

Take a look at this


https://nomorerust.com/store/home/17-mastercoat-ultimate-prep-prime-paint-kit.html

I've had good luck on smaller irregular sized parts by filling a container a couple inches deep with water, then placing an oversized piece of plastic over it and setting the rusted part in it. once in, start adding rust removal liquid and at the same time bring up the water level outside the liner until the part is submerged.
I think you could do something similar with your vat and a piece of pond liner and wood cribbing or plywood at bottom to insulate the liner from sharp edges. Using this process one can use far less rust removal product. Large voids in casting can be filled with other containers (i.e. milk jugs0 full of water. On small items I use marbles, paperweights and other rusted parts. Basically using water outside the liner and other items to displace rust removal product against the part.

I treated my leaf springs with Evaporust. I constructed a simple wood frame from 2x4's that just fit around one spring. I set it on the garage floor and lined it with 6mil poly. I placed the spring inside and added sand between the wood and poly, eventually creating a pond in the shape of the spring. I did use some containers to fill voids as I was running low on sand. It worked great and allowed me to install the second spring when I removed the first. Clean up was a breeze; simply scooped the liquid up and put it back in the jug. I had bough the 1 gallon container, which was more than enough for this purpose.

From the wording of the question from 420SIX, I am assuming the metal part in question is a piece that will be painted. If that is the case, then a product with phosphoric acid will give primer and paint better adhesion and offer long term durability for the finish. If the part is plated or natural finish, molasses or oxalic acid are two options for rust removal. I used oxalic acid on a Barracuda rear bumper. As stated by others, I built a vat with lumber and a poly liner, or paint "drop cloth". After rust removal, I treated the bare metal with Boeshield T9 Rust and Corrosion Protection.

David

Great now I need to know what is safe to clean my laptop screen of Iced Tea

I used 3-1/2 gallons of molasses for my vat, 8’x8’x14” deep, I’m thinking that’s about 150-200 gallons, working great so far, foaming big time.

i am always amazed at moparts, find the easy way to do something and 10 guys will come up with a harder plan. Its like everybody is an engineer trying to re invent the wheel. "first i prep the metal by playing Kenny G's greatest hits on repeat for 2 weeks, Then i rub the steel by hand with cotton gloves until 72*. Then use cotton balls to gently fluff off the rust, be careful removing anything off the metal, its very thin and even a cotton ball will warp it"

so machine is too big to blast but moparts has decided a vat of molasses will work for removing its rust. anybody know how to get farm equipment into a swimming pool filled with molasses?

i am a blaster. I see this everyday, people trying to find the hardest way to do something. blast it, prime it, paint it, have beer

Well with a vat I don’t have to get grit out of every crack on my body. I throw it in there for two weeks then let it do all the work. I use all of these methods depending on the piece.