I understand from people who have seen the Marlin film of Colour Case Hardening that it contains a number of factual errors. Such as there being no top on the crucible when it is put into and withdrawn from the furnace. Also the the very close proximity of the operators hand to the supposedly red hot crucible. (already mentioned here). It has been suggested that the film was made to be deliberately misleading in order to foil competitors seeking to emulate Marlins methods and colours.
Harry
Your "foil the competitors" analysis of the Marlin film sounds more than plausible. I speak from experience.
Back in college, I had a summer job working in an iron foundry where we melted and cast ductile iron into pipe fittings. I even got a tryout on the "pouring deck", where overhead cranes brought crucibles of molten iron (about 5 or 10 gallons at a time) to us, suspended from chain hoists. The job on the pouring deck was to use the power chain hoist and a ship's wheel to pour a stream of molten iron from the crucible into the tiny, tiny openings atop a row of sand moulds as they waddled by on a conveyor belt. Needless to say (and, I think, to my parents' enjoying their later-fulfilled hope of raising a college graduate rather than an iron-pourer), I didn't last long in the job. My aim was crappy and I spilled too much while pouring too slowly.
In that job, I wore a hardhat with a blackout full-faceshield over safety glasses, earplugs and mouth-and-nose dustmask, full-length leather apron over aluminized overalls, heavy work boots, long-sleeved shirt and elbow-length insulated (>1/4 inch) leather work gloves and gauntlets. Even though this guy is not working with
molten metal there is no f'g way anyone - OSHA industrial safety rules or not - would put their ungloved hands that close to any container of glowing hot metal. In the first place, it would be too damn hot to hold - the worker would have burned his hands. The worker also would not have been able to maintain a grip for a long time - like an entire shift.
Moreover, when something is glowing yellow-hot - molten or not - most camera films will show an effect from the radiant heat. There will be a nimbus- or aurora-like effect, similar to the glowing halo one sees around spaceship engines or radioactive sources in science-fiction flicks. This is noticeable with the naked eye when working around molten or extremely hot metal (or any material, for that matter) and does show up on film. (I once captured the effect myself, while photographing glassblowers at work at some little shop in Venice.) The Marlin film does not appear to reflect that phenomenon.
Finally, there's the whole "hot metal and water don't mix" thing. While CCH is a "controlled" black art, doing so in an area with a lot of clutter - like the Marlin film - is a prescription for burning down the house. There's always the risk of a steam explosion or worse, "worse" in the
molten metal context meaning a hydrogen explosion (b/c there's enough energy loose in a mass of molten steel to disassociate water into hydrogen and oxygen, which then recombine explosively) or, at a minimum, splattering lots of meteors of molten steel in every direction and burning through anything in the way, animal, vegetable or mineral.
Just saying....
