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.
http://www.youtube.com/watch?v=xXGSV1pwMnE

http://www.sculptnouveau.com/Details.cfm?ProdIDx&category=6
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.

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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.

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.

On 22/04/13 13:44, Wild_Bill wrote:
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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.

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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%.
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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.

On 22/04/13 15:20, Existential Angst wrote:
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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.

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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

wrote:
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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.
==================================== 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.

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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

On Mon, 22 Apr 2013 04:23:20 -0400, "Wild_Bill"
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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:
http://www.flickr.com/photos/27683124@N07/6342267183/in/set-72157605638700703
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

Yep, the narrative portion was flawed, but I thought the visual effect of the sheet blackening was surprising.

On Mon, 22 Apr 2013 19:02:59 -0700, snipped-for-privacy@gmail.com wrote:
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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.
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Ed Huntress wrote:
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M.K, what do you mean by that? Something about that blanket statement don't seem quite right. (in this context)
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Wow, that's cool to know. No wonder my rattle can paint ain't stikin to my "cleaned" parts worth anything. :)
Alvin in AZ

On Sun, 5 May 2013 21:57:26 +0000 (UTC), snipped-for-privacy@Example.com wrote:
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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.

On 05/05/13 22:57, snipped-for-privacy@Example.com wrote:
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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.

On Sun, 05 May 2013 23:58:36 +0100, David Billington
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Wow. Does he do restoration on the old plywood-chassis Marcos? Or is he making parts for new ones?

On 06/05/13 00:01, Ed Huntress wrote:
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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.

On Mon, 06 May 2013 00:51:38 +0100, David Billington
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Aha.The pitch in the sports car press here, years ago, was that the plywood chassis required too much labor. I don't have any other information on it, except that the same comment was made in one of my coffee-table car books. The steel space frame was cheaper to build at the time. I'll bet they brazed it, like a lot of specialty Brit car manufacturers did.
Plywood actually is a very good material for making high-performance chassis. It's good for shear panels and it's good for those multi-box tubs, the early ones, that were sometimes called "monocoque" but which weren't. They were a collection of shear-panel boxes, generally made of sheet aluminum, but they could be much stiffer in plywood. They've been used in a variety of structures but I don't know of any cars built that way. I've heard that the "appropriate technology" mini cars that Renault had designed for indiginous construction in Africa a couple of decades ago were designed that way, but I never saw one, or even photos of them.
The Marcos, IIRC, was a little different. I saw some photos of the old Marcos wooden chassis once upon a time, and it looked like the frame of a big hydroplane or plywood airplane -- circa 1960. It was a highly engineered structure. My recollection is that it was a series of crosswise bulkheads tied together with upright longitudinal panels. It looked like the skin might be stressed, too, but I don't know.
You probably know this but it's a potentially useful point worth repeating: a good-quality plywood, like Bruynzeel or one of its copy-cats, has a weight/stiffness value, and a weight/strength value, roughly equivalent to a medium-strength cored composite. For example, S-glass fabric and epoxy sandwiching high-density polyurethane foam. Twenty-five years ago, that was a high-performance composite.
The performance of a well-engineered plywood structure of that type is at least as good as, and maybe better than, a fully triangulated tubular spaceframe.
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I hope someone got that down on paper or other recording. Too many of those gems just get lost.

On Sun, 5 May 2013 21:57:26 +0000 (UTC), snipped-for-privacy@Example.com wrote:
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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

On Sun, 5 May 2013 21:57:26 +0000 (UTC), snipped-for-privacy@Example.com wrote:
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I've always preferred lacquer thinner. Both are too damned expensive these days. Someone is making billions off 'em. (Probably the greenies.)