How many times when you were growing up, did your mother tell you to never use that "sing song" taunting type of phrase to boast of your accomplishments? In a recent issue of Anoplate News, we struck a nerve
when it came to the description of our new black oxide line in Building 400. It seems that several current customers, and also some potential
accounts, have contacted us and questioned why we would invest that
heavily in "that old fashioned process".  Why not just use one of those new cold blacks? All you have to do today is look in your finishing or machining journals and you are bound to see an advertisement for a room temperature blackening process. They are promoted as safe, easy to use, done in house and an economical means of treating your parts. 

Some of what they say is correct. Being a room temperature process, it is certainly safer from a splash stand point since hot black oxide is 285 degrees F. If your production is one's and two's, machined all over with no rust or heat treat oxides (therefore minimizing acid cleaning), a small jar of cold black might be a good bet.  Anoplate even stocks a few gallons of
concentrate for touch up purposes. A different formulation is required for
various base metals such as copper, aluminum and steel. Large
production of parts in the table lamp and jewelry industry are both a natural for these cold processes since filigree is blackened, then highlighted by buffing. Both are not overly sensitive to a uniform deep black and are usually topped with a lacquer.

The word safe has more than one connotation however. All cold black formulations contain selenium, which has been recently put on the EPA's "dirty dozen list", so it may not be "safe" to put in your sewer. The Materials Handbook states the following about selenium: "the material is highly poisonous and is used in insecticides. Foods grown in soils containing selenium may have toxic effects and some weeds growing in western states have high concentrations of selenium and are poisonous to animals eating them". You would now be possibly subject to control by your local POTW (Public Owned Treatment Works). This also brings in OSHA since face shields and protective clothing may be required. The state and federal forms can be very time consuming and you may now require a environmental consultant. This paragraph started out to talk about safety and has turned into is it really "economical".

One thing that Anoplate has had trouble with, using "cold blacks", is the cosmetic quality.. Never, have we been able to give it a cosmetic rating, anywhere near our hot black process. The larger the part, the lower the rating. One common requirement for either hot or cold process is a good quality oil. Neither is very good without a good protective top film.. Our feeling is the hot process is harder, more abrasion resistant and more reproducible.

What specifications do these cold processes meet? There is no MIL-SPEC, ASTM Standard or major commercial standard (at least in our current customer base), that recognizes use of this type of product. MIL-C-13924D and AMS 2485 do control the hot blackening of ferrous base materials and ISO 11408 discusses the general topic of black oxide. If you wish to try out a cold process yourself, get a sample and give it a go. We will be glad to run, no charge, a hot black sample on a similar part, and you evaluate the difference. After running the cold black test, beyond the cosmetic evaluation, see what time you have expended, and evaluate just how "economical" the do it yourself process really is. I would expect only in a limited few cases will we find it less expensive than the hot process. If you would like to see our nice black oxide on steel and stainless department, get in touch with Milt Stevenson, Sr. 315-471-6143 (x-156) for a tour.