For those who wanted the formula for blackening steel,
Here you go…The formula for black oxide on steel (not stainless):
Potassium Hydroxide 15 gms
Sodium Hydroxide 640 gms
Sodium nitrate 20 gms
Distilled water 880 gms
Add all the chemicals to the water, and bring to a rolling boil in a
clean, stainless steel beaker or similar container. Simply emerse the
piece to be oxidized into the beaker…it MUST come in contact with
the beaker (so don’t suspend it). Attaching a thin piece of stainless
steel wire to the piece will allow you to easily retrieve it. After
you have achieved the desired color, simply wipe dry with a cotton
cloth.
This oxide will be the final finish so, if you want it polished, do
your polishing (or satin, sandblast, engraving, stonesetting, etc.)
first. If you change your mind about the finish, or a client has
scratched the piece and would like it reconditioned, simply emerse
the piece again. You can seal this formula after using it, and store
it for later use. No, I don’t know what the maximum shelf life is…
This is the part where I add the usual disclaimers: 1. If you don’t
know how to handle chemicals safely, get assistance from someone who
does. 2. Boiling liquids are hot…use common sense, or find someone
who has some to assist you. 3. Not all stones like to be dropped in
boiling water. If you are not sure if the stone can take it, play it
safe or test a less valuable, but similar, stone. I have
successfully used this oxide with set emeralds, but I knew that they
were not oiled or treated and I avoided the thermal shock by placing
them in the liquid while it was only at room temperature, brought the
temperature up slowly, and let it cool down slowly. 4. This stuff
does not like skin. It is a little caustic, and will cause
irritation. Wear gloves, eye protection, etc…you know the drill.
Don’t get this stuff in your mouth. Make sure you have really, REALLY
rinsed the jewelry when you’re through. 5. This stuff does not like
acid, either, so make sure that hollow forms are free of any pickle.
This finish is only an oxide, but is quite durable. Since it does not
color gold or platinum, or titanium, these metals really stand out
against the black background.
Let me know how this works out. Doug Zaruba