Blacken Stainless Steel Patina Darken Metal Finishes

I've tried some retail store cold bluing products on cold & hot rolled steel
parts, and have seen the sketchy results which weren't impressive.
I was looking for a cold method to darken a small stainless part (no idea
which alloy) and thought this video was very impressive.
First, I used silicon carbide abrasive to break up the straight/parallel
graining lines of the manufacturer's finish. This dulled the sparkle
somewhat.
I tried phosphoric to knock down the sparkle, but it didn't show much effect
after ~1/2 hour.
Then tried liquid Harris Stay Brite flux (zinc chloride and hydrochloric),
and it had little effect.
It now has a more weathered look which was about all I wanted.
The company selling the product has an 8oz size for ~$15, not sure about
where in the US they are, or how much shipping would be.
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It appears to me that an 8oz bottle would blacken a lot of small parts. They
have a lot of other products for other metals and various results/colors.
Reply to
Wild_Bill
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There is a company somewhere that actually colors SS, much like anodized aluminum. I got the impression the finish was not super durable, but I only got to see a bevy of 1" sqaure swatches. Perty neat, tho. Just fyi.
I guess a torch is out of the question? Shades of straw gold to dark blue with that.
Scotchbrite can also re-grain SS. I use it to actually satin-finish/polish the mill-finish off SS. Spinning rounds on a lathe is super quick, and they make scotchbrite belts for belt sanders.
Reply to
Existential Angst
Heat wasn't an option for this unless I woulda wanted to disassemble the mechanism and torch it (with some acid on it), which I'm certain woulda worked. The flashy flickering shine is gone, which was what I was after.
That video of blackening the sheet of ss on the worktable was impressive. The stuff from the trigger-spray bottle (no special equipment or application method) was changing the ss to black immediately upon contact.
Some waiting was involved, but room temperature black with not much effort.. most of the work appeared to be cleaning/prepping the sheet.
Reply to
Wild_Bill
I watched the youtube video and it was quite obvious the commentator didn't know much about what he was talking about with comments about sanding through the chromium and nickel. The comment about the solution being a very strong acid also raised alarm as he was spraying it on with a hand trigger pump and wiping it off onto the floor, seems a bad technique for a strong acid.
Reply to
David Billington
Sulfur does that with silver; I wonder if the active ingredient in this spary is doing something similar with chromium. Chromium, in decent SS, iirc, is sizable, somewhere around 15-20%. F'sure at least 10%.
There is such a thing as chrome plated SS, I"ve seen it. I don't quite understand it, but I've seen it. I'm sure the platers were happy to get the job. :) :) Copper is (or was) often used as the "base" for chrome plating, mebbe nickel is as well.
Reply to
Existential Angst
IIRC the copper can be built up and easily polished to remove defects and the nickel provides a seal coat as the chromium plate is porous. In the video though I don't think it was plated SS as the commentator mentioned the chromium and nickel would migrate back to the surface over time to provide a degree of corrosion protection to the blacked SS.
Reply to
David Billington
I looked at the MDS . It contains Selenium. Might be interesting to try some selenium from the vitamin counter or shampoo with selenium on some stainless.
Dan
Reply to
dcaster
I looked at the MDS . It contains Selenium. Might be interesting to try some selenium from the vitamin counter or shampoo with selenium on some stainless.
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Orbitally, this could make some sense. Both Silver and chromium have outer S1 orbitals, and sulfur and selenium both have outer p4 orbitals. There could very well be analogous bonding, for which there is large precedence.
However, selenium in a vitamin is not in its metallic (zero oxidation) state, and proly wouldn't react. Same difference as the sodium in NaCl and Na the pure metal. But, couldn't hurt to try. The Cl- in sea water embrittles SS (supposedly), so ions can have reactive effects.
Reply to
Existential Angst
Most really black SS parts are black chrome plated. I've got a bunch of laptop trim screws that that was done to, matches the case. If you like messing with hot and caustic solutions, Brownell's sells "bluing" salts for stainless that do the job and are fairly durable, downside is that you're messing with a boiling saturated solution of stuff that will eat holes in you and your clothing if you get any on you and is toxic waste when you get done with them. But they will do the job. Most cold bluing consists of putting down a thin layer of metallic copper, then coloring that, the oxide layer on stainless keeps that from happening. Probably any cold "bluing" you'll get won't be that durable. If you're doing outside sculpture stuff, it definitely isn't going to last long. A good two-part auto body urethane might be in order for that case.
Stan
Reply to
Stanley Schaefer
I will not comment on using this product on stainless steel as I have no direct experience with it. I use Birchwood Casey's Gun Blue patina routinely on mild steel with good results:
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and a few others in the same set.
However, I feel I have to comment on some of the statements in the video:
1) I would not use 70% isopropanol - use 99%.
2) Isopropanol will not neutralize anything - certainly not an acid. The 99% preparation is weakly acidic.
3) I have learned not to use acetone as a final surface prep for patinas. All the acetone available locally leaves a slight oily residue which plays havoc with patinas.
4) I use a two step process of cleaning - start with acetone, varsol or isopropanol depending on the piece. I then go to Zep Heavy Duty followed by a rinse with the final rinse using *distilled water* and then drying either by hot air or baking.
5) Before the drying I do a waterbreak test (usually part of the final rinse). If the piece fails, start again.
6) I do not know what an IMS cleaner is but all the ones I use are alkaline, not acid.
7) Rubbing the patina with Scotchbrite will not "rub the patina in". It will remove loose patina and allow for the next layer to adhere.
8) Finally, I do not know about stainless, but mild steel finished to a 40 grit and patinated with Gun Blue will rust before your very eyes. I usually finish to about 400 grit which buys me time to top coat.
Michael Koblic, Campbell River, BC
Reply to
mkoblic
Yep, the narrative portion was flawed, but I thought the visual effect of the sheet blackening was surprising.
Reply to
Wild_Bill
FWIW, virtually all of the consumer-grade acetone on the market is recycled industrial product. It almost always contains some oil.
To get virgin acetone you either need to buy a scientific lab grade, or find a source of the pure industrial grade.
We had the latter stuff where I worked at Ranger Yachts as a bonder, right out of college. Any oil would be a killer in laying up boat hulls, so it was certified virgin.
Reply to
Ed Huntress
"Wild_Bill" wrote in news:fs6dt.227370$ snipped-for-privacy@en-nntp-03.dc.easynews.com:
Years ago I was etching some printed circuit boards using ferric chloride from Radio Hack. I had a polished stainless hemostat that I used to fish the board out. It immediately turn a dull black. I never bothered to polish them up again, and they still have a dull grey finish after a couple decades of use for other stuff.
Might be worth experimenting with.
Doug White
Reply to
Doug White
I just tried this with a what I think is 304. It did not blacken it but it etched it instead. Photo on my website
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Regards,
Boris Mohar
Got Knock? - see: Viatrack Printed Circuit Designs (among other things)
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void _-void-_ in the obvious place
Reply to
Boris Mohar
M.K, what do you mean by that? Something about that blanket statement don't seem quite right. (in this context)
Wow, that's cool to know. No wonder my rattle can paint ain't stikin to my "cleaned" parts worth anything. :)
Alvin in AZ
Reply to
alvinj
That's a bad thing. But what's *really* bad is to watch your boat delaminate from under you when you're 12 miles out to sea.. d8-)
Seriously, it's the reason behind some consumer-grade problems with polyester resin and fiberglass. Many people know that off-the-shelf polyester needs to be cleaned before laminating more to a hardened layer, or painting it, because of the wax that floats the surface. (Polyester is air-inhibited in curing, so they put in some wax.) So they use acetone, because they know that's good stuff for stripping off any uncured film, as well as the wax, and then they find that nothing sticks to it very well afterwards.
Other problems are just crappy polyester, with too much styrene monomer in it. Styrene is cheaper. In hardware stores, you're likely to get polyester that's stretched pretty far with styrene.
Also, FWIW, both epoxy and ordinary polyester resins have real adhesion problems, including the adhesion of paint, with hardened layers. But epoxy is easier to deal with. The film on the surface of that is called "amine blush," and you don't need solvents to get it off. It washes off with warm water and detergent -- straight TSP being preferred.
Don't use acetone. It doesn't work. Neither does sanding. It just spreads it around. But you can sand for mechanical grip after the soap-and-water wash.
Reply to
Ed Huntress
In the UK for removing residues prior to painting I use what we call "Panel wipe" a solvent mix intended for that purpose and available from any good auto paint supplier. I can look at the ingredient list tomorrow if the can has one but I don't recall acetone being on the list. IIRC I have heard of the problem with common acetone being recycled and possibly contaminated from a local guy that does a lot of fibreglass work associated with Marcos cars.
Reply to
David Billington
Wow. Does he do restoration on the old plywood-chassis Marcos? Or is he making parts for new ones?
Reply to
Ed Huntress
Acic will not neutralize acid. In the video he says to use 70% isopropanol to neutralize the cleaner which is itself acid.
Michael Koblic, Campbell River, BC
Reply to
mkoblic
I think he might do both. I live in the part of the UK where the Marcos was made and lots of people are still about that worked for them at one time or another. IIRC the switch from the plywood chassis to steel wasn't due to any inherent advantage of steel but due to problems sourcing top quality marine ply back in the 1960s? due to some political problems with dealing with Honduras or a major plywood supplying country. A guy that used to live near me, former GT40 works driver Terry Sanger, mentioned he worked for Jem Marsh and they would be building up a race car only to come into work the next week to find it sold and have to start over. I have seen Terry speak on a few occasions and he has a vast experience, extensive photo record on slides, and a very good speaker and mentioned one incident of a flywheel coming loose in a wooden Marcos and lots of sawdust but no limbs lost.
Reply to
David Billington

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