Rust Removal From Mateing Machined Surfaces

[Sawyer911]

Well with all the talent here I am hoping to get some direction to clean up 2 blistered and pock marked machined surfaces.

They are the 15 degreed angled surfaces that are the fixed and rotating parts of my 1942 Mosler Money chest.

This thing is a beast at 1600 pounds and the 20" round door must be in the hundreds of pounds range. It was poorly stored in a basement and the once beautiful polished surfaces suffered a lot of corrosion. Due to this I can't rotate the door closed, even when it was new anything on the surface could prevent rotating open/closed.

I tried a few things but doesn't make a super smooth surface. So far tried scraping with razor blades than steelwool with WD40 and than a brass wire wheel.

Material is cast steel.

First picture is after I did a clear coat (patina look) and second after I painted the interior gloss white and third is a picture of the opening. I need to get maybe a close up of the area of concern.

Thanks in advance

Sawyer

[Ayles]

How did you get it out of the basement??

[masraum]

WOW! So it's basically just a huge, heavy safe, but with very high tolerances.

I'd say the way to go is reverse electrolysis which is what lots of folks use when restoring rusty old tools, but thats too big and too heavy.

I feel like a solution that should work would be sanding with a very fine grit wet/dry sandpaper. Rather than using water (the norm when wet sanding), I'd use something like Windex (often used when sharpening tools like plane blades and chisels) or a cutting oil, like the oil used in some sharpening systems (like Lansky). I'd probably use the sand paper in conjunction with a block or curved surface to help keep things flat.

Sanding should get you a smooth surface (better than steel wool or a wire brush, I would think).

And then immediately afterwards, a light coat of either oil or wax (wax is often used to protect old tools, but oil should also work).

[Arizona_928]

Oil it.
Wire wheel
Etc

[Sawyer911]

I got a guy to get it on a pallet and drag it up planks with a little Bobcat skid steerer before I picked it up..

I didn't know the weight at the time and when we loaded it in the bed of a pickup it really lowered the back down.

Well I knew it was over 1200 pounds as I couldn't pick it up with my compact tractor.

Lots of cribbing, pry bars and pipes to get it inside my garage.

Oh and the worst part was he rolled the safe over on its side onto the pallet and when I got it close to my overhead door I used my engine hoist and more cribbing to rotate it back on it's bottom. I did take advantage to paint the bottom first.

This thing is 24x24x24 of cast steel.

Sawyer

[908/930]

Try something like Rust-oleum rust dissolver gel, POR 15 also makes some products.

[Ayles]

Originally Posted by masraum

WOW! So it's basically just a huge, heavy safe, but with very high tolerances.

I'd say the way to go is reverse electrolysis which is what lots of folks use when restoring rusty old tools, but thats too big and too heavy.

I feel like a solution that should work would be sanding with a very fine grit wet/dry sandpaper. Rather than using water (the norm when wet sanding), I'd use something like Windex (often used when sharpening tools like plane blades and chisels) or a cutting oil, like the oil used in some sharpening systems (like Lansky). I'd probably use the sand paper in conjunction with a block or curved surface to help keep things flat.

Sanding should get you a smooth surface (better than steel wool or a wire brush, I would think).

And then immediately afterwards, a light coat of either oil or wax (wax is often used to protect old tools, but oil should also work).

When I restored my drillpress I wet sanded the table portion with a petroleum-based product. I think it was pb blaster I had sitting around. It worked amazingly and has not rerusted in several years.

[masraum]

Originally Posted by 908/930

Try something like Rust-oleum rust dissolver gel, POR 15 also makes some products.

I'd be concerned that it would be difficult to neutralize/clean afterwards. Maybe the stuff that converts rust to a black coating? But I suspect that would still require some sanding (before or or possible and after application)

[wdfifteen]

I would use pure phosphoric acid to dissolve the iron oxide. Don’t use those “rust converters” because they have an added polymer that builds up and acts as a coating. Once you get the steel good and clean you can use wax or oil to coat the steel and prevent further rust.

[masraum]

Originally Posted by wdfifteen

I would use pure phosphoric acid to dissolve the iron oxide. Don’t use those “rust converters” because they have an added polymer that builds up and acts as a coating. Once you get the steel good and clean you can use wax or oil to coat the steel and prevent further rust.

I assume you want to be very sure that you then neutralize any acid with a base (baking soda) and then thoroughly rinse any remnants of the acid and/or base away, and then get rid of the water (so it doesn't create more/new rust).

There's also "evaporust" which is a product that gets a lot of press these days for various things.

I'd be concerned with most caustic chemical solutions (acid, base). I believe that using an acid will potentially cause new damage (in addition to what was caused by the rust).

[Ayles]

Originally Posted by masraum

I assume you want to be very sure that you then neutralize any acid with a base (baking soda) and then thoroughly rinse any remnants of the acid and/or base away, and then get rid of the water (so it doesn't create more/new rust).

There's also "evaporust" which is a product that gets a lot of press these days for various things.

I'd be concerned with most caustic chemical solutions (acid, base). I believe that using an acid will potentially cause new damage (in addition to what was caused by the rust).

The acids are going to cause a lot of problems for the newly painted interior. Wet sanding should be pretty safe.

[908/930]

I use the Rust oleum rust dissolver for paint touch ups on my truck and other cars, really not that strong, has not affected the nearby paint. Not like it's going to eat a hole through anything.

[Bill Douglas]

I'd sand blast it then strip it down to get all the bits clean then refinish it.

[wdfifteen]

Originally Posted by masraum

I assume you want to be very sure that you then neutralize any acid with a base (baking soda) and then thoroughly rinse any remnants of the acid.

I’m sorry. I don’t think I was clear. By “pure” I didn’t mean high molarity, I meant unadulterated by polymers or other protective finishes. I don’t know the molarity of pre-paint acid washes is, but use something like that. It will convert the iron oxide to a softer, more easily removed compound. Basically you don’t want the product to remove the rust that obstructs free movement just to replace it with something else that will obstruct free movement of the door against the jamb. You want to remove the rust, then add your own protectant that is also lubricating.

[LWJ]

First. This is super cool. Second. You either need abrasives or chemicals.

What about dry ice blasting? A wild shot.

I do know that I cleaned up my rusted table saw with green scotch bright and wd40. Then cleaned off with simple green. Wiped super clean and waxed with Johnson’s paste wax (RIP! Miss that stuff). Table top was worse than what you have and has been great for years.

[fanaudical]

If you don't have a sand blaster: Mild acetic acid (vinegar) is where I'd start. Wire brush to remove the loose stuff, soak with vinegar, wait a day, repeat. This will remove quite a bit of it without damaging the surrounding metal. Once it's mostly clean, move to a red Scotchbrite wheel and some phosphoric acid metal prep.

[pavulon]

Is laser rust removal affordable and widely available yet?

[masraum]

Originally Posted by LWJ

I do know that I cleaned up my rusted table saw with green scotch bright and wd40. Then cleaned off with simple green. Wiped super clean and waxed with Johnson’s paste wax (RIP! Miss that stuff). Table top was worse than what you have and has been great for years.

I'm on an "old tools sales" group on Facebook, and cans of old Johnson's paste wax go for $50-75. It's crazy.

[look 171]

We prep our our cast iron table saws with a simple 3-400 grit wet and dry sand paper (we just use WD40) wrapped around a block of wood to get surface rust out. The wood block keeps everything flat. We aren't removing a lot of materials here just surface rust.

[Sawyer911]

Wow thanks for all the current input. I did try to razor blade the blisters off and it does take it down to see the factory grind marks, Not very smooth but was a start.

I can't use any rust converters as they will fill in the rotating gap.

I have most of the products mentioned here kicking around so I'll start there.

I did the paint as this thing is sitting in the way and where I need to move it I can work on the door opening.

This is Cast Steel and not Iron, amazing as it is cast together than opening is machined, the inside and exterior have rough mold marking and chisel marks all over while removing the casting material.

I think maybe I'll try blade scrapping, than oil (wet) sand and see if vinegar would help clean the craters. I have lots of 3M wet o dry from 320 - 3000 so I'll use 320 - 400 grit and see where that gets me.

I did try a wire brush by hand and one on my die grinder and they really didn't have much impact

I'll keep you all posted as I throw whatever I can at it.

Sawyer