Well I wanted to give the group an update on the Casswell cold process black
oxide coating for metal.

2.5 gallon kit purchased for about $80.00 from Casswell in NY. (FAST
SHIPPING!)

I prepped my parts as per the instructions and have had mixed results. Some
pieces of the same 1018 cold rolled metal stock blackened well while others
came out blotchy. I can only guess that this is due to grease or other
impurities on the metal.

The process is straight forward and I found that leaving the part in about
12 minutes has worked the best. I slightly preheat the solution (9 parts
distilled water 1 part blackening chemicals) to about 85-90 degrees prior to
suspending the parts in the tub (plastic pail provided). The parts must be
suspended, not placed in a basket, dropped to the bottom of the pail etc..
or uneven etching will take place. After 12 minutes I rinse the part in
water and immediately blow dry with an airhose. The final process is to dip,
brush, spray etc.. a sealer (included with the kit) on the part that
protects it from rust. The sealer takes a LONG time to dry so plan on
overnight drying.

Overall if you are extremely judicious in your parts cleaning, sandblasting
seems best, the finish is pretty good. It is not as hard of a finish as heat
based black oxide systems but it is really easy to use. Not something I
would recommend for any volume but for a small batch of parts that are
cleaned extremely well, it's not a bad product. Home based projects will
benefit the most from this I believe. Commercial applications might not be
pleased as much as the traditional heat based blackening process.

I currently have 2-3K parts blackened annually by an outside vendor and my
only complaint with the heat based process is the salt bloom evident after
about a month in an assembled part. This eventually leads to rust after 3
months and therefore is a problem with trying to treat assembled parts. We
are probably going to pre-treat all parts individually and then assemble
them to work around this issue.

Hope this helps someone. Thanks for everyone's input!

Pedroman