Re: Raven Finish

Posted by Larry Jenkins on September 10, 1998 at 15:50:20

In Reply to: Re: Raven Finish
posted by carla on September 09, 1998 at 16:38:04

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: :
: : I haven't been able to come-up with a good way to heat more than one nut or bolt at a time.Which make it very time consuming to do a whole project.And I've often wondered; "How much of the temper do I take out of the bolt when I heat it".Should this really be a concern?Thanks again.

: hi, geo.

: yes, heating any heat-treated steel part to a dull red will destroy the heat-treat.

: the proper way to do a black finish would be to use a "hot caustic" commercial oxidising chemical, available from any platers' supplier. this is mixed with distilled water and brought to a boil in a suitable tank. the work is immersed a few minutes, then dried and oiled. the caustic material is dangerous to use, and requires safety gloves, goggles, etc.

:
: "parkerising" is approximately the same process, using a slightly different material. "black oxide" and "parkerising" are the standard industrial processes for finishing steel parts.

: a much better alternative for small batches of parts, in my opinion, is to use a commercial cold oxidiser. the "oxpho" brand sold by "brownells" (515-623-5401) seems to work far better than the "birchwood casey" brand sold under different trade names by "eastwood" and others. a $13 bottle of the stuff will do literally dozens of small parts, maybe hundreds of nut and bolt items.

: the "secret" is merely to have the steel parts perfectly clean -- a light glass-blast is best, but a fine wire wheel works alright-- dipping the parts two or three times and lightly scrubbing them with fine steel wool whilst wet with the oxidant will bring up an excellent dark blue-black finish.

: i have used the "oxpho" material to completely refinish a number of pre-war winchesters-- done carefully, one can get a finish which will be every bit as good, if not better, than the "du-lite" process the winchester works used after 1939 or so, but not quite the equivalent of the earlier slow rust blues.--

: this may be a bit of "over-kill" for automotive work, but, with a bit of care, you can have small parts looking exactly as they did when new. this material is not nearly so hazardous as a hot caustic process, but you should wear light rubber safety gloves, and safety glasses anyway, just to play safe.

: hope this helps

: carla

HI Carla..

Heating parts to a "dull red" will not take out the hardness of the steel."Bright red" will.Most Model A fasteners were not "heat treated".

Larry Jenkins


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