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Homemade Evapo-rust

Jidis

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It was polished to 1000 grit wet/dry before the peroxide/salt solution.
Looks good! Yeah, I remember reading that the initial surface prep was one of the reasons people were always unhappy with the results from those "home bluing" kits. I've had some interest in that as I've been reluctantly leaving a lot of my homemade steel stuff unfinished lately. Some attempts at heat treating got me a cool looking dark coat which seemed pretty tough, but it wasn't uniform enough around the part to look intentional. I'd be interested in whatever recipe you arrived at for the peroxide/salt process.

Thanks!
 

kev74

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Looks good! Yeah, I remember reading that the initial surface prep was one of the reasons people were always unhappy with the results from those "home bluing" kits. I've had some interest in that as I've been reluctantly leaving a lot of my homemade steel stuff unfinished lately. Some attempts at heat treating got me a cool looking dark coat which seemed pretty tough, but it wasn't uniform enough around the part to look intentional. I'd be interested in whatever recipe you arrived at for the peroxide/salt process.

Thanks!
I'm still working out the kinks. I'll write something up when I get a little more proficient.
 

whitmore

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Do you guys have a preference on solutions for stuff which can't be soaked? I was attacked by a rust wave a few years back and still have some things which need to be cleaned up, but there's a bunch of stuff like my radial arm saw column, bar clamps,etc. which obviously can't be removed and dipped in anything.
There's three or four options: one, is to use metal polish (the drippy kind); this has a mild abrasive which
won't cut steel, but takes out soft rust easily. That's labor-intensive, obviously. A damp rag afterward,
and a bit of paste wax, will usually be useful. Every dot of rust can have a hygroscopic core that will
attract moisture and dig a pit, you do want to wash as well as rub.

Another, is to make the rust into dust, and try to vacuum most of it away: wire wheel, steel
wool, <sand,glass bead>blasting, metal-finishing Scotchbrite pads (gray, brown, etc.),
and a perennial favorite, LASERS. <
>
It makes a mess, obviously (outdoors, with face shield, gloves, breathing mask, coveralls...)

Wax or oil applied afterward is a good idea; I keep a paraffin-soaked shop rag,
and warm bits of steel with a flame or hotplate, then rub with the rag, to give some
rust-resistance. I melted some paraffin and cheese wax together to charge the
rag, but beeswax is traditional.

You can also apply conversion coatings, which do a kind of bluing, to make black
oxide from the brown rust. Oiling with boiled linseed oil was an old variant on this,
and would usually be fine for woodwork equipment.
 

Jidis

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Do any of you metalheads know what sort of state steel is in after you hit it with something strong like muriatic acid? I was messing with Kev's bluing process last week, and though I didn't manage to get his sort of results, I've noticed a cool intermediate look that stuff has after the acid wash, where it turns sort of a dull pewter gray. Can that be any sort of desirable finish or is it prone to something? It's usually a really even uniform coat and color.

-Thanks! (still waiting on the Harbor Freight version of that laser rig)
 

Bob Korves

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Do any of you metalheads know what sort of state steel is in after you hit it with something strong like muriatic acid? I was messing with Kev's bluing process last week, and though I didn't manage to get his sort of results, I've noticed a cool intermediate look that stuff has after the acid wash, where it turns sort of a dull pewter gray. Can that be any sort of desirable finish or is it prone to something? It's usually a really even uniform coat and color.

-Thanks! (still waiting on the Harbor Freight version of that laser rig)
The dull gray is from microscopic pitting caused by the Muriatic (also called Hydrochloric) acid. The acid attacks the base metal as well as the rust. Don't use acids on something that you want to retain it's shininess after rust removal. If you want to retain the shiny finish, use something like Evapo-rust or electrolysis that does not attack the metal.
 

whitmore

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Do any of you metalheads know what sort of state steel is in after you hit it with something strong like muriatic acid?
Most smooth metal is burnished/polished/cold rolled, and that makes for flat surfaces, but with surface stresses. Acid etching
erodes the surface slightly, and does so in a way that reveals the crystalline structure of the metal. So, the dull finish
is a mosaic-like reveal of the underlying crystal structure of the metal. Try it on a blue-steel razor blade, the visual effect is
quite dramatic. On wrought iron, it displays the 'grain' of that metal. It also shows underlying strains from stamped
serial numbers, even if they have been filed away (but not overstruck, or welded over).

Alas, clean metal is likely to rust from the slightest things; unless your next step is bluing, or welding, or painting, such a finish
will age in random ways.
 

Jidis

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Thanks for the replies!

Whitmore- I do recall having one or two things get light surface rust shortly after the semi-etch from the acid, but I think it didn't happen on spots which had a smoother finish. You don't sound like there's any easy way to keep the look unfortunately. When you say painting, I was wondering about a clear coat, but most of it is tool holders and tool accessories which will probably get enough abuse to wear through spots. Can you just wax or oil the crap out of it? If not, I probably need to get back to the bluing thing.

Thanks Again

PS- This "X" was done with the acid. You can see some of the rust, but I actually wanted it to rust a little in this case.X.jpg
 

homebrewed

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This is an old thread, but....

I have a few comments from a chemistry perspective. There was a question in this thread regarding substituting oxy-clean for the peroxide. That won't work because oxy-clean is sodium percarbonate, which is a basic (not acidic) compound. Mixing it with vinegar will neutralize the vinegar, probably not what you want for removing rust. It would be good for neutralizing residual acid on your de-rusted parts though.

Also, the suggestion of mixing peroxide with muriatic (hydrochloric) acid is dangerous. I worked in a chem lab and was investigating different peroxide mixtures to etch some very refactory materials, and tried mixing the two. Within seconds the mixture started releasing bubbles of chlorine gas!! Hydrogen peroxide is a very powerful oxidizing agent, in this case reacting with the hydrogen in the HCl molecule and releasing the chlorine as a gas. Of course, I did the experiment under a fume hood.

While I used concentrated hydrochloric acid and 30% hydrogen peroxide (neither one is commonly available), that result was enough to halt any further experiments along those lines. I write this, having worked with some really nasty chemicals (including red fuming nitric acid and concentrated hydrofluoric acid) over the years with NO injuries. PPE's are your friend when it comes to chemicals.

Just because you can buy OTC chemicals doesn't mean you can mix them willy-nilly. Do some online searching before picking up the mixing spoon.
 

RJSakowski

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As I recall, concentrated hydrochloric acid is 36% HCl whereas the muriatic acid that I buy at the local DIY is 31.45% HCl.
 

homebrewed

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Yes, the acronym I was using means Personal Protection Equipment. I'm familiar with polyphenyl ethers as diffusion pump oil because they are quite resistant to oxidation. Wish they had been around when I was a grad student, it would have saved me from a nasty cleanup job when the lab's diffusion pump lost its coolant flow.
 

homebrewed

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As I recall, concentrated hydrochloric acid is 36% HCl whereas the muriatic acid that I buy at the local DIY is 31.45% HCl.
That's pretty strong stuff! I didn't think it was that concentrated. Thanks for the info!
 

mickri

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I tried some of this home made evapo rust. Soaked some heavily rusted parts off my midget overnight. It took some of the rust off. Still had to scrub with a wire brush and there is still rust. I made up another batch. Left out the water and added more salt. I'll report back tomorrow on how this batch worked.
 

mickri

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I was just going by the OP's formula and what he called it.
 

mickri

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After soaking stuff for another 24 hours all I can say is that I am not impressed. It doesn't seem to work any better than other home brewed rust removers that I have used and it did some serious etching. Probably the salt caused the etching. Don't know. I'm not a chemist.
 
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