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How to coat a bone in stainless steel
August 20, 2014 12:26 PM   Subscribe

Let's say you wanted to coat bones, on an industrial, mass production scale, in stainless steel, without damaging the bones underneath too much.

What processes and steps would you need to do. What type of facilities would you need?

In the same vein, if you needed to coat a small number bones in stainless steel on an ad hock, MacGyver-y way, if you had access to the stuff in a regular house and maybe a trip to Home Depot?
posted by bswinburn to Science & Nature (15 answers total) 5 users marked this as a favorite
 
Does it have to have the structural strength of stainless steel, or just look like stainless steel?

One of these is much harder than the other.
posted by Oktober at 12:30 PM on August 20


Actual stainless would be best; although I'd be interested in stuff that just looks like stainless too.
posted by bswinburn at 12:31 PM on August 20


There's stainless steel foil, although I don't know if you can get it at Home Depot. You can ship it from grainger.com, but I don't know how malleable it is to work with. I would definitely wear thick gloves at the least to prevent wicked cuts.

If you're imagining, like, dipping bones in molten stainless steel? The melting point of stainless steel is somewhere around 1400°C which would incinerate bone.

If I just wanted bones to look like stainless steel, I would try sealing the bone and spray painting.

Newer 3D printing technologies can use a laser to melt powdered stainless steel into complex computerized shapes, but again, I don't know if a bone could hold up as a printing surface. If you don't actually care about the bone being inside the stainless steel, the bone could be 3D scanned and replicated.
posted by muddgirl at 12:39 PM on August 20


My instinct is to say that powder coating would be the way to do this, but I have no idea if that would work with bone.

It is definitely possible to chrome bone, apparently.
posted by showbiz_liz at 12:42 PM on August 20


What thickness are you looking for?
posted by spikeleemajortomdickandharryconnickjrmints at 12:45 PM on August 20 [2 favorites]


Talk to a jeweller about dipping. I've dipped a dead seahorse and a mummified dead newt* in gold, so although the melting point for stainless is higher than gold, it's lower than platinum, so this is within a jeweller's wheel house.

RIP little dude
posted by DarlingBri at 12:46 PM on August 20 [4 favorites]


Physical Vapor Deposition may do it.
posted by Sophont at 12:48 PM on August 20


Regarding seahorses in gold: those are made with something similar to lost wax casting. Something similar could be used to make a bone shaped piece of metal but the organic material does not survive if that is the goal.
posted by sunslice at 1:03 PM on August 20


I wonder if they were actually dipped or electroformed? (which involved adding an electrically conducted layer, then attracting the gold, silver, or platinum particles to the surface - it's actually pretty easy to do this at home, at least with copper and nickel.) Unfortunately stainless steel appears to be difficult to electroform, and I have no idea if the original survives the process, if that is the goal.
posted by muddgirl at 1:05 PM on August 20


(On second thought, I think it definitely would survive, but again, it's difficult if not impossible to do this with stainless steel.)
posted by muddgirl at 1:10 PM on August 20


What's your objective?

a) You want the bones to resemble shiny, mirror-polished metal, like a chrome-plated bumper? or
b) You want the bones to look like steel, and to not rust outside (mirror polish optional).

a) Maybe try wrapping the bones with mylar. If you're into true chrome-plating, you need to get a metal surface onto the bones. Chrome plating (on metal!) is typically a three step process: first a layer of copper, then of nickel, and finally the chrome.
b) Are you an artist who's working up a metal-bone sculpture? Stainless is hard, and difficult to work with, but you might use the original bones to make molds for casting solid stainless-steel bones.

A lot of the shiny stuff on cars these days is plastic with a faux-shiny-metal surface -- I don't know how that's done, but I've observed that coating flake off of old pieces.
posted by Rash at 1:30 PM on August 20


What processes and steps would you need to do. What type of facilities would you need?

Aside from huge steel foundries of which I know very little, there are bronze foundries that also cast stainless.

Here's a decent write-up for bronze. You'd want an outbuilding in the country or a space in an industrial park where you'd have a dedicated 24/7 tumbling drum for your ceramic shell investment so that it didn't settle and seize up, as well as a big furnace for burning the wax out of your investment-coated sculpt, and a slightly smaller furnace for melting the crucible of bronze stainless. (I don't know if small-scale shops use crucibles for stainless or some specialized furnace like a cupola furnace?) That's on top of a bead/sand blasting station, torches/welding for touch-up, etc.

I think you'd want a space about the size of a 4 car garage, and an absence of neighbors. And fire insurance; the local guy's outbuilding burnt down once when his crockpot of wax didn't stay turned off.

It's somewhat easier to make rubber molds of the bones, pour waxes, and take the waxes to a foundry, either an art-bronze foundry that does stainless or an industrial stainless steel foundry.

I would make the rubber molds in a mold-making class where an experienced technician can walk you through some of the fiddly stuff. Bones have lots of finicky shapes and are more difficult to mold than an apple. And the rubber is extraordinarily expensive; $10-15 a pound, assuming no wastage on mistakes and no skilled labor costs.

What I would do is take the bones to a chrome plating shop, myself.
posted by sebastienbailard at 1:56 PM on August 20 [1 favorite]


Sintering, maybe. I'm sure this would be an involved process that would require a lot of trial and error before it really worked right. Getting the powder to stick on the bone in a uniform layer seems like it would be a challenge, and fusing it successfully would probably depend on the shape of the bone (a rib would be a lot easier than a skull).
posted by adamrice at 3:11 PM on August 20


A bronze human femur might run you $250 to $500+ from an art bronze foundry, btw. Less in a developing country. I quite suspect a one-off stainless steel cast piece from an art foundry will cost more. I won't posit any guesses about industrial non-art foundries or mass production quantities.

The people to ask about this stuff are in the public forum at http://www.finishing.com/letters/index.html

However, consider the comments to this Youtube video on "Plating Copper with 316L Stainless Steel":

stainless steel is mostly and alloy of steel chromium and nickel so if you try to use it in electroplating it will tend to dissociate into basic elements and the most electro negative one will plate the cathode

That in mind, you can go buy a chorome plating kit, line up personal safety stuff and disposal stuff, and go wild. Try to keep it out of your lungs, eyes, and groundwater.
posted by sebastienbailard at 8:30 PM on August 20


If it can pump down properly in high vacuum, then that bone can go into a vacuum chamber for sputter coating. Bone should have a pretty low vapor pressure but the porosity might cause problems. The stoichiometry of the coating might not be the same as stainless and it would have different material properties due to columnar, non(nano maybe?)-crystalline growth. This is a thing that I absolutely believe could be done.

Methods used to electroplate onto plastic may be applicable to bone, maybe not.

If you are looking for a mirror finish-reflective coating you'd have to build up the surface a macroscopic amount as well as having a polsihed finish.

These are decorative and not for some wolverine-type project? My first attempt at an industrial scale project would be to find an electroless process to form an adherent conductive layer on the bone itself (mostly calcium oxide, right?) then build that layer up with copper to fill voids. Then a chrome or nickel plate followed by a final polish to make things look nice.

Shoot, electropolishing is an acid process, so the acid copper and nickel bath might totally dissolve the bones. You could do an interlayer, maybe epoxy/plastic dip of some sort to prevent acid attack of the bones. That then needs electroless deposition of some sort.

You might have to go electroless all the way, a topic I don't know much about.
posted by Dmenet at 4:15 PM on August 21


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