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Letter 9059
Black Zink or Black Oxidation process for
stainless steel screws
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I need to have about 50 different screws made black. Our company
makes medical instruments. We can not have our screws rust. However,
we also need them black. The problem is that we do not have large
quantities.
I have been quoted anywhere from $18 to $60 dollars per line item,
or lot, up to 25 pounds. One promising quote was 50 pounds of screws
for $150 dollars. However I don't know if I would have to put all of
my screws in together. If I did that I would have to sort them out,
which would be almost impossible.
I only have about half a pound of each screw. So at the $18 per
screw type I would need to pay $900 dollars to have only 25 pounds
processed. One option may be to keep my screws separated in a metal
mesh. I have been told that this would work in a powder coating
process.
I would like to hear from people who are willing to explain their
pricing scale.
Michael Earl Laub
Sapidyne - Boise, Idaho
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I do not think that black oxide would be acceptable for most
medical instruments. Since that is a terribly broad area, it might be
OK.
I would look at black chrome. It is jet black and is used on
numerous decorative and jewelery items.
You might be able to find a vapor deposition process that would
give you a black finish, possibly on the head only, that is very
durable and affordable.
Most black oxide setups are quite large and are not really setup
to handle small quanities. They also work at very high temps. There
are very small barrel plating setups that would easily handle 1/2
pounds of screws.
Consider mixing large with small screws that you could easily
seperate as a cost savings measure. Have people seperate them on
their coffee breaks.--Free coffee.
I think that you can probably buy the screws,or some of them, all
ready black from someone.
James Watts
- FL
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Mr. Watts:
In your response to Mr. Laub, you suggest a "black chrome" finish
for (I assume) steel screws. Are you referring to "black rhodium" or
"black nickel" plating, or something else? I am very interested in
finding a way to put a black matte finish on iron or steel jewelry
that is durable enough for reasonable wear. Gunsmith "bluing"
treatments scratch and wear quite easily, so that's out. Baked on
polymer sprays like "Aluma-Hyde" don't wear well either. Any
suggestions? I would also like to learn of a DURABLE black coating
for silicon bronze. The usual patina processes are far too fragile.
Thanks in advance!
Wayne Emery
Jewelry Design Studio - Tacoma, WA, USA
++
Mil-Std-792, Type II marking methods might be helpful for small
quantities. The specification is available form the US Government
site: http://astimage.daps.dla.mil/quicksearch
The depth of penetration of the markings is required to be greater
than 0.0005" and typically the color is described as black, although
that may vary to brown or bluish tones depending on the chemistry of
the metal and the etching compounds.
A quick look using your favorite search engine for
"electrochemical etch" should give you commercial sites where the
electrical equipment and chemicals are available. The equipment
purchase (or perhaps rental?) is the largest cost, but that's
one-time only and a little chemical goes a long way. The only
challenge is getting a marker head that is flexible enough to get
into the threads of the screws, but if all you are concerned with is
the visible screw-heads, that may not be a problem.
Dave Hass
Arinc, Inc - Oklahoma City, USA
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