case coloring

I am interested in the case coloring process of metal.
Is anyone familar with the process?

if you are refering to color case hardening it is done with a molten cyanide bath (dont breathe the fumes very poisonus)
or
in a crucible using bone that has been heated until it crumbles. the parts to be colored are packed in the crucible so that they are completely surrounded by the bone medium and then heated for a period ot time then quenched in water.
you can get the prepared bone medium from brownells i believe...jim

There are companies that specalise in color case hardening I dont know who they are though.
From the instructers at school it is not somthing to try and do your self.

This class was given summer 2004 at Lassen College. However the clowns that maintain the "Official Website" have yet to post the Fall 2004 courses, even though I know the printed schedule is available. You can reach them at 530.251.8800 via telephone.

However, you are in luck as I was able to find the class schedule I had taken when I was at a summer course in early July. In fact, you are doubly in luck as the Color Case Hardening class (GSS 59.4) is scheduled for December 6-Dec 10. It is a full time 5 day class, not two three hour class sessions per week over a three month period.

[ 10-24-2004, 01:21 AM: Message edited by: GGaskill ]

Try www.doublegun.com for CC info. There is a retired prof. from UofI., I think, who is quite knowledgeable about this. I want to say Dr. Gaddy, but I am not sure.-Jerald

I'd be interested in seeing more about it, too. I've hardened and heat treated quite a few items since the late 70's, and do play a bit with the colors, sometimes. To get the full range, generally, the part is going to be at a pretty high tempering temperature. For instance these parts are essentially springs, to back up the cutting tool (plane iron) They are air-hard steel, tempered back to about 540F (not critical for the app, basically still around 59 -60Rc for airhard). For water hardening (1095) that would be a little lower, maybe 55Rc. If you go over about 575 - 600, the colors all disappear and the steel is just grey again. Around 475, +/- 20 degress or so, there is a range wher you get beautiful golds and coppers, the higher temps fading into purples. I often make cutting tools that are a pale luminescent(sp?) gold, just for the effect.



I am mostly interested in the condition, so these are done in the kitchen oven, and I leave a bit of oil on them. The oil helps provide a surface range of temps that give the mix of colors, instead of all one color.

For instance, you can see in these that the coloring was sort of an afterthought. To do it right, the metal prep needs to be flawless. coloring won't hide scratches or poor surface finsish (as you can see in the photos! ) I was playing with the idea of coloring since the parts had to be tempered anyway, but had expected to polish off the surface to bright after heat treat. I sort of like the effect though, and might polish them and retemper for a better color/finish combination. Or not. there's too much to do int life!

If you can work from the backside of the metal, for cosmetic purposes, you can run a flame around, and it will give the dispersion out from the center of the flame, in all the colors.

Again, lately the effect for items like this has some appeal, and I would be happy to see others experiences and information related to the control of the comsmetics aspects.

smt

There are older methods described in detail in

Older Gunsmithing books as authored by Dunlap and another 2 volume set by Howe.

It involves polishing and scruplous cleaning of the steel parts,packing them in a steel or iron closed cylinder with a quick dissconect type of cap filled with Bone charcoal & chard Leather scraps.

The whole assembly is then placed in a forge and roasted.

After the prescribed time & temperature soak the
parts are dumped into a cylinder of rain water which has compressed air bubbling up through a fine porous bottom plate.
Like a froath.
The finer the bubbles the finer the coloring ie..
( size and pattern ).

Requires a LOT of Experimenting !!

Regards,

Steve

For those who want to try this, consider
reading "The Bullseye Mixture" in TMBR number
(I think) one.

The parts are dumped into water, with compressed
air bubbling up through it - and often there
is oil added to the water as well.

Jim

This is a base cavity punch I made to go with a set of 58 cal Minie swage dies. It is actually much better looking in person. I had to fudge the hue and saturation to get the color to show well and they all didn't. Maybe something to do with taking the photo under floresent light? There was tinges of red, grays, some yellow and then the larger patchs of blue.

I used a modified format of what I read about what Harrington & Richardson used for thier process. I used a liter pop bottle with the top cut off so I had a tall cylinder. I made a saturated brine solution (H&R used KNO3). I then floated about 1/8" of spindle oil on top. I used a piece of 3/16 copper tube and bent it into a "J" shape to stick into the water. I put a piece of vacuum tubing on it and had my wife blow through it to create the turbulence.

Yep, she thought I was freaking crazy when I asked her, but she did it. Glad I warned her about the hot steel first! I heated the part in a torch flame until it was bright orange (W-1 steel) and held it there a bit. It was then dunked and withdrawn and dunked deeper each time until dropped and it fell to the bottom.

I was very happy with how it turned out. Dave Trumbull is in no danger

Best,
Rick

Shotgun actions or receivers are usually placed in some type of jig to keep them from warping. So, If you have something that has to remain unaltered, think about a jig of some type-Jerald