cleaning cast iron

[that-guy]

I have two cast iron wood stoves that my grandfather built back in the 50's. both were used inside of a log cabin until about 20 years ago, then they both sat out in an open garage. what would be the best media to use to get them cleaned up of all of the scale and rust on them? also, what would be the best coating to get them looking presentable again and take the intense heat when I put them back into use???

 

[Fretters]

Regarding rust, you don't have to be excessive with cast as it is quite resilient to rust. Getting a good wood burn going in the stove and then just wire brushing it would likely sort any rust. If not, electrolysis, media blasting, wire wheel/cup etc. will all work.

Regarding finish, a mix of Linseed oil, graphite and lamp black will make an old style stove black you can apply. A bit of beeswax can be added to make it into a cream rather than a liquid if you desire.

 

[jakemac]

I have two cast iron wood stoves that my grandfather built back in the 50's. both were used inside of a log cabin until about 20 years ago, then they both sat out in an open garage. what would be the best media to use to get them cleaned up of all of the scale and rust on them?

Elbow grease.
Seriously. Don't sandblast cast iron. Walnut shells might work, but you'd be better off using a wire brush by hand to start with. An electrolysis tank will work, but may be too big depending on the size of the stoves. For the smaller parts, you could soak them in White Vinegar then wire brush. The sides shouldn't matter much, but the top should be smooth. So, lightly hand sanding with increasingly finer grits of sandpaper. Finish with fine steel wool.

also, what would be the best coating to get them looking presentable again and take the intense heat when I put them back into use???

For the top I'd only use "Lamp Black", it's sometimes sold as "Stove Black" and can be found in a REAL hardware store that's well stocked. It would work for the rest of the stove as well. If you need to, you could use black engine paint for the sides, but I wouldn't use it on the cook-surface.

 

[theoldwizard1]

All wood burning stoves have joints. Many of those joint use high temp gasket or sealant. Older stoves should be checked carefully.

The door gasket should be replaced.

 

[gungatim]

I have just used a wire wheel on a 4" grinder, then used rustoleum hi-heat stove paint. for the top cooking surface, I just season with some vegetable oil.

 

[n8n]

I'd be hesitant to use acid on cast iron, ruined a Packard water pump housing once that way Turned all soft and flaky before the rust came off.

Electrolysis if you have a tank big enough, otherwise I second the cup wire brush recommendation.

 

[malibu101]

Seriously. Don't sandblast cast iron. Walnut shells might work, but you'd be better off using a wire brush by hand to start with. An electrolysis tank will work, but may be too big depending on the size of the stoves. For the smaller parts, you could soak them in White Vinegar then wire brush. The sides shouldn't matter much, but the top should be smooth. So, lightly hand sanding with increasingly finer grits of sandpaper. Finish with fine steel wool.
.

Just wondering why you make that coverall statement? What is so bad about it?
I have a HF pressure pot that I sometimes blast small pieces with outside in the alley. I don't blast much or often and I can't recall blasting cast iron but I would have without thinking twice about it.
What would happen if I do?

 

[ZRX61]

For the top I'd only use "Lamp Black", it's sometimes sold as "Stove Black" and can be found in a REAL hardware store that's well stocked. It would work for the rest of the stove as well. If you need to, you could use black engine paint for the sides, but I wouldn't use it on the cook-surface.

Also called graphite polish, comes it tubes like toothpaste. Rub it on, buff it with a soft cloth & the stoves will gleam

 

[Packard V8]

Seriously. Don't sandblast cast iron.

Just wondering why you make that coverall statement? What is so bad about it? . . . What would happen if I do?

X2 on not having a clue where that recommendation is coming from. Every afternoon, cast iron engine blocks and heads go into a 600-degree bake oven to burn off grease and oil, are taken out the next morning and put into an industrial steel shot blast cabinet before being machined and reused. This standard procedure is much more intense and abrasive than sandblasting.

I've sandblasted and shotblasted, cast iron pans, stoves, tools, machinery and every iron engine part and seen no harm, only a quick, clean surface to machine or paint. The only caveat is if there is a finish-machined surface or fine casting detail to be protected.

jack vines

 

[BirdMobile]

Heat it, then scrub with a little vegetable oil mixed with salt. Use old newspapers to apply the salt/oil paste and scrub with. Works wonders on old, rusty cast iron.

 

[that-guy]

I did some searching and am going to take the doors and other small parts off put into a bath of "Evaporust" to see how it treats those parts, then from there. the stoves are pretty large, so it would take ALOT of the solution to do the main body of it, but I might beable to put some gallon water jugs in there to displace some of the solution. I will report back with my findings

 

[jakemac]

Just wondering why you make that coverall statement? What is so bad about it?
I have a HF pressure pot that I sometimes blast small pieces with outside in the alley. I don't blast much or often and I can't recall blasting cast iron but I would have without thinking twice about it.
What would happen if I do?

X2 on not having a clue where that recommendation is coming from. Every afternoon, cast iron engine blocks and heads go into a 600-degree bake oven to burn off grease and oil, are taken out the next morning and put into an industrial steel shot blast cabinet before being machined and reused. This standard procedure is much more intense and abrasive than sandblasting.

I've sandblasted and shotblasted, cast iron pans, stoves, tools, machinery and every iron engine part and seen no harm, only a quick, clean surface to machine or paint. The only caveat is if there is a finish-machined surface or fine casting detail to be protected.

jack vines

To be honest, I was just passing on a warning that has been given in the vise thread several times. I'm not certain, but it may have something to do with cast iron being porous.

I did some searching and am going to take the doors and other small parts off put into a bath of "Evaporust" to see how it treats those parts, then from there. the stoves are pretty large, so it would take ALOT of the solution to do the main body of it, but I might beable to put some gallon water jugs in there to displace some of the solution. I will report back with my findings

You could try the paper towel method on the main body. Use a wire brush to get any scale and flaky rust off the pieces. Then, using EvapoRust in a spray bottle, lay paper towels down on the metal, soaking the towels with the ER. Push out any air bubbles, and keep the towels wet until the rust has been converted. You may need to change out the paper towels during the process to allow the ER to get down to the surface as the rust is converted.

 

[Packard V8]

To be honest, I was just passing on a warning that has been given in the vise thread several times. I'm not certain, but it may have something to do with cast iron being porous.

Thanks for the clarification. Anyone's opinions and results may differ, but the opinion backed by experience carries more weight.

I've sandblasted and shotblasted a couple dozen vises which greatly benefited from the process. Protect the jaw faces, machined surfaces such as a Wilton slide and any fine cast-in detail or lettering. Too much time or pressure can dull those. The rest come out shining and ready for paint.

BTW - back when, I worked in a steel and iron foundry. Every casting was "snagged" on a heavy bench grinder to remove sprues and then run through the steel shot blaster. The idea they could be damaged by sandblasting wasn't even considered a possibility. Most vises have probably been there as the first step out of the mold in their finishing process.

jack vines

 

[Fretters]

Protect the jaw faces, machined surfaces such as a Wilton slide and any fine cast-in detail or lettering. Too much time or pressure can dull those.

That's why the sand blasting is not recommended by some, (myself included), with machinery and the like. The effect it can give on machined surfaces if they're not protected from the media, plus the fact that it does remove all original patina, potentially removes some good metal and can affect any surface features. For restoration work, there are far subtler methods.

If it was an ornate stove, then I'd honestly give the same caution as Jake did. If it's just a standard flat featureless one though, there's not really owt it can hurt.

 

[Outlawmws]

I'm wondering; if the OP's grandfather made these stoves if they are actually cast iron or not. I've made numerous stove. a very few had a cast feature, but the average Joe ain't equipped for molding Cast.

Likely these are Plate Stoves? (Meaning made from plate.)

Can you post some pics?

And I'm with Fretters, I don't care for the finish sand blasting leaves. Other medias do different things; some OK, some...

 

[SteveCh]

I brought home an old cast-iron stove someone was going to throw in the dump. I took it apart, sand-blasted all pieces with a very fine sand, bought new stove bolts and cement, reassembled. Used it for ten years and gave it to someone else who was at the dump. No problems.

After clean-up, I just used high-temp black spray paint before I put it back together. I never noticed any ill effects from anything I did to it.

 

[Carla]

Elbow grease.
Seriously. Don't sandblast cast iron. Walnut shells might work, but you'd be better off using a wire brush by hand to start with. An electrolysis tank will work, but may be too big depending on the size of the stoves. For the smaller parts, you could soak them in White Vinegar then wire brush. The sides shouldn't matter much, but the top should be smooth. So, lightly hand sanding with increasingly finer grits of sandpaper. Finish with fine steel wool.


The warning about sandblasting in the 'vises' thread was a good one, for people who are amateurs at restoring old equipment.

Actually 'media-blasting' covers a very wide range of materials and techniques.

Sending a vise, or any similar class of parts, to the class of sandblasters who do structural iron, such as bridges, or concrete or brick building walls, etc, would be a really, really bad idea, as the grit of sand, and the pressures, they commonly use would badly pit any machined surface, and could, indeed, warp (from heating....that sand creates a lot of friction as it strikes) even such as thin stove castings. Actually, that level of sandblasting power could dig/wear holes through thin stove castings rather quickly, if concentrated in one spot even relatively briefly.

Gentle media-blasting, using walnut shell or fine glass-beads, run at low pressures, and used carefully, is a very different story.

One must still take care to mask off any machined surface, to be prudent, but blast-cleaning, carefully done with gentle media, should not pit machined or other smooth metal surfaces. (a good example of this would be die-cast zinc-alloy carburetter castings......easily pitted, with just a little too much blast pressure, but rendered 'sparkly-clean' with the smooth cast finish 'as new', if done carefully.)

cheers

Carla

 

[theoldwizard1]

I did some searching and am going to take the doors and other small parts off put into a bath of "Evaporust" to see how it treats those parts, then from there. the stoves are pretty large, so it would take ALOT of the solution to do the main body of it, but I might beable to put some gallon water jugs in there to displace some of the solution. I will report back with my findings

Looking forward to that ! Picture if possible.

 

[that-guy]

Looking forward to that ! Picture if possible.

I'm gonna buy a gallon or so this weekend and atleast get the small parts soaked to see how well it works