doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Case Coloring

well then, buy all means fire up the furnace and start cookin dem receivers...


http://wn.com/what_is_case_hardening


the video where larry cooks that old parker receiver is particularly interesting. wonder if he had any trouble putting that gun back together?

I wanted to add this because Miller's point about temper when re-casing is important.

This is from a Table on "The Working of Steel" located within the Gutenberg Project, 1920ish Metalworking manual.
Techniques based on the technology of the time.

TABLE 23.�TEMPERING TEMPERATURES FOR STEELS
Temperature
for 1 hr. Color Temperature
for 8 min. Uses
Deg. F. Deg. C. Deg. F. Deg. C.
370 188 Faint yellow 460 238 Scrapers, brass-turning tools, reamers, taps, milling cutters, saw teeth.
390 199 Light straw 510 265 Twist drills, lathe tools, planer tools, finishing tools
410 210 Dark straw 560 293 Stone tools, hammer faces, chisels for hard work, boring cutters.
430 221 Brown 610 321 Trephining tools, stamps.
450 232 Purple 640 337 Cold chisels for ordinary work, carpenters' tools, picks, cold punches, shear blades, slicing tools, slotter tools.
490 254 Dark blue 660 343 Hot chisels, tools for hot work, springs.
510 265 Light blue 710 376 Springs, screw drivers.
It will be noted that two sets of temperatures are shown, one being specified for a time interval of 8 min. and the other for 1 hr. For the finest work the longer time is preferable, while for ordinary rough work 8 min. is sufficient, after the steel has reached the specified temperature.


So why post this?
Because we see annealing ocurring in 8 minutes or less. At quite low surface temperatures. Also, remembering that case is quite thin.


One technique I have read about, but have never seen performed, would be to electro plate the part with a heavy layer of copper. Shielding from plating areas that re-casing might be desired. Then briefly re-casing for a shallow case, and then quenching in a bath of effervescence. Copper then removed.

Anyone ever heard of that?

clapper: interesting, but please explain how this relates to heat treating of sxs shotgun receivers...

The aesthetic appeal of case hardeing colors is a mystery to me, but to each his own. Does anyone know of a reliable way to hasten the fading of the blue-brown to the patina that is revealed after case colors fade? No, not the coin finished stage, but that soft grey which for my taste is about as good looking a metal surface as can be.

I tried steel wool, gentle abrasives but cannot get that soft sheen. I guess what is needed is some polite alternative to human sweat. Well, it is a better alternative to some other body fluids mentioned above.

I'll confirm this with my best friend after he comes in off the lake, but in my view, "You can't get there from here."

If someone has a secret way to get a receiver from room temp to a colorable temperature, without going through the tempering zone, I'm all ears.

And No, Ed, I'm not talking about paint.

lover: you sound like a Belgian. they don't like case colors either, but prefer a pewter like appearance to their shotgun receivers.

exposure to direct sunlight seems to naturally fade case colors. ever notice how many guns from texas and other places south are void of case colors?

you might try naval jelly or sodium hydrosulfide. they are both strong oxidizers...

clapper: watch larry's video referenced above. he preheats his oven to 1400 degrees before inserting his packed crucible...wonder what the heat curve looks like?

Ed- I've seen many videos related to heat treating. Larry P. jigs up everything he puts in the crucible. As many companies have consistent patterns on their colored parts, I'm pretty sure they shield their parts the same way every time, to get the color pattern they desire.

My only real curiosity about this anymore is "Can patterned oxides (and other films) be created at the surface of a previously case hardened part, without the carbon atoms beneath the film migrating out?" I'd need to see sections from a sacrificial part to develop my opinion.

Please read the MSDS, Kasenit is a mixture of Carbon black, and Ferro Cyanide compounds.

I wonder if the carbon left at all. I thought the environment in the pack, to create the colors, is carbon (CO?) rich and blocks oxygen. You'd think the surface might pick up a tad more carbon if colors show up.