doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Video of Colour Case Hardening Quench

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....

bubble, bubble, toil and trouble....

A couple of things about the Marlin film. They show a very large oven. Crucibles are packed with parts and charcoal.The box (crucible) is placed in the oven. They do no show a top being placed on the box, nor one being removed. I have assumed the film maker simply did not bother to include that step. The film is a 2 reeler, so he had to edit for time / content.

The crucible is handled with a separate tool that grips it. They show the crucible being packed. Then they show a number of crucibles being placed in the oven. Next we see 1 crucible being removed. The worker suddenly appears at barrel. The barrel appears to have a pipe of running water in it. The entire crucible is then tilted into the water.

The whole thing about gloves would be more a safety issue than heat related.

In a 24 minute film the CCH section is under 60 seconds. They spend more time showing the factory entrance and select Marlin executives.

These type of films are not a "How it's made" episode. They were bragging pieces. A way for the company to show the entire factory operation.

I find them useful for small bits of information about the process. Actually, I found it more interesting to see all the jigs they used to shape the stocks and the press to do the forgings.

I strongly encourage any one who is interested to purchase the film themselves. Here is the contact I had at the time,
if any one is interested, Harvey Frakes MFCA 217-585-3454 between 6pm & 10pm CST

Pete

Heh. You try it without gloves and see how quickly you drop it and turn a heat issue into a safety issue.

Why would anyone drop it? The tool is approximately 5' long and has not been in the oven.

Pete

I don't think the heat in the Marlin pictures is that big an issue either. Not molten by any means, probably closer to 1400*. Still lots of danger to be had, but note the original post video, no glowing yellow heat as the box is taken out to the quench bucket.

The Marlin holder seems to be made for the job, lets the case hardener stand back before the quick turn quench. I'd agree,even if they're throwing a curve ball, still a valuable piece of firearms history.

Thanks for taking the time to show your video Ballistixs. I think your colors came out great. Any quick comment on how you steer the blues towards the center of a part.

Take care, Craig

Craig, the crucible was glowing red hot when it was taken out of the kiln...you just can't see it very well on the video. True it was a little cooler by the time it got to the quench tank but still very hot.

The centre of the parts cool the slowest because they are the hottest and take the longest to cool down. That's about the science of it. The art of this process is to cool the parts whilst keeping as much as the media around them as they hit the water...that's where the colour comes in.


T

Thanks Tony. I've been able to try the process many times with good success. I think you're doing very well, and I appreciate that you were able to share it.

Thanks for your comments, Craig

Tony,

Sorry if things got a little off topic. I only meant to show what long tradition you are following. Your case colors look great. I appreciate your efforts.

Where are you getting the charcoal?

Pete

Pete: I used to get the charcoal from Peter Dyson over here but it was pre-mixed and I wanted more control. So recently Doug kindly had some bone and wood charcoal in separate containers sent over from Brownells and I've been custom mixing since and it's improved my colours I think.
Cheers
T