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jerrywh

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Has any of you engravers ever had a gun with copper inlays case hardened? If so what was the effect on the copper inlays??
 

John B.

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#3
The melting point of copper is 1984 degrees F. as you probably know.
Most original charcoal pack heat case color hardening is at 2010 degrees, if memory serves.
I have not tried this myself with copper inlays.
But would advise consulting Doug Turnbull for info.
He does great color case work and has a wealth of knowledge on the subject.
Also consider and ask about chemical color case.
 

flintdoubles

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Case colors are done at around 1350 to 1400 degrees Fahrenheit far less than the melting point of copper. The color should stay bright because of the lack of oxygen in the pack but I have only done it with silver and gold.
 
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#5
I do fair bit of glass enameling on copper and heating to circa 1400 will more than likely result in developing some firescale - unless you can do it in oxygen free environment. This can be cleaned and removed, just something to keep in mind. At times, firescale on copper can be stubborn though. There are products to prevent fire scale such firescoff or scale preventer etc. Enameling supply companies will have these. However, after it is cleaned - copper itself will remain unaffected.
 

tdelewis

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I think If you check Ron Smith's book You may find that he didn't use copper but different alloys of gold silver and copper to get the desired look. It is amazing what he has done to get the different color inlays. I'm sure that copper would be OK for case coloring. But, I'm no expert on this. I do know that dissimilar metals, when in contact with each other can cause problems and it might cause the inlay to decay and come out. Using gold alloys such as white gold and pink gold would solve the problem as the gold doesn't react with other metals so well..
 

Jonathan.Silas

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I think If you check Ron Smith's book You may find that he didn't use copper but different alloys of gold silver and copper to get the desired look. It is amazing what he has done to get the different color inlays. I'm sure that copper would be OK for case coloring. But, I'm no expert on this. I do know that dissimilar metals, when in contact with each other can cause problems and it might cause the inlay to decay and come out. Using gold alloys such as white gold and pink gold would solve the problem as the gold doesn't react with other metals so well..
Do you happen to have the title of Mr Smith's book handy. Sir?
 

jerrywh

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Thread starter #10
The copper inlays I am thinking of case hardening has very fine engraving on it so I am looking for specific answers. I have all the books previously mentioned.
 

SamW

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#11
Jerry, I would call Doug Turnbull and get his input. I started a good many years ago leaving off the finest detail for inlays that are going through the rust blue or case hardening process, finishing them after the process.

I would think fire scale would be the prime worry and I just don't know what happens when the parts are dumped into the quince.
 

jerrywh

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I do a lot of case hardening but never case hardened a gun with copper inlays. I never have seen a gun that doug turnbull did with them either. I think what I will do is just take a piece of copper and run it through the process and see what happens. Thanks for the input. I have a hunch that Brian Hochsrtat might know. Just thought I would save myself some work and ask.
 

mitch

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#14
instead of just taking "a piece of copper and run it through the process", i would recommend doing a simple inlay in a steel plate or scrap part, to better replicate the full process. maybe put some fine/narrow points in the inlay, which would be most prone to damage. also, if you do larger areas with wire (i'm a sheet man), do a bit of that to see if they separate or behave strangely.

let us know how it goes!
 
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#16
Hello all,
Did a small experiment with small piece of steel (reasonably hard but not best quality) and small (rushed) inlay with copper wire (dead soft jeweler's wire).
Entire piece is about 1" x 3/4".

1. Gave steel bit of a grind/polish followed by rough inlay, I left the edges purposely rough to see if copper will expand/move with heat. Followed with my usual pre-enameling treatment (scrub and polish to have things clean).

2. Heated with torch to about 1450º, note the red enamel I applied next to the inlay - this was my way of judging the temp (more-less since my ground glass will start melting around 1300-1400 and flows around 1450-1500). As it can be seen, steel acquired bluish colour and copper developed firescale (this much I expected). There was a bit of reaction in the rough edges of the inlay. Also, some minor spotty firescale to steel.

3. Cleaned up with sparex #2 (pickle). Normally I would immerse the whole piece but wanted to keep my pickle clean of steel and simply applied with cotton swab soaked in the pickle. Plus, if one is doing a large part - this proves that spotty cleanup should work fine. Followed by a gentle polish with 1" radial discs (Dedeco or 3M brand). I did not bother to do mirror finish. As it can be seen, copper inlay itself stayed in place. Seems like when done on quality steel and with nice clean inlay job - things should stay as intended.
Hope this gives you something to work with.

P.S. Enamel is poor since such steel serves for bad enameling medium (excessive bubbling due to composition etc.).
1.JPG 2.JPG 3.JPG
Happy Holidays everyone!
 

Mike Cirelli

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#18
Color case hardening is done much the same way except that generally only leather and bone are used as the carbon source. I don't know why this works better than charcoal, but it does. You get more brilliant colors with them. The other thing you do is modify the quenching bath. You need a source of bubbles. LOTS of bubbles to really rile up the quench bath. Adding a bit of potassium nitrate to the water increases the brilliance of the colors as well, but isn't a requirement. You have to watch the temperature more closely with color case hardening or the colors won't come out well. Don't go over 1350 °F.

https://www.finishing.com/21/08.shtml
 

John B.

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#19
Good to hear from you Mr. Mike.That is good information. Thank you.

The Brits get the good case color by using rabbit hides in the bone charcoal mix.
As well as air bubbles, the water temperature is important. But I don't remember what it is.
The temp, charcoal size, rabbit hides, the air bubbles and bubble size and the water temp all work together to control the size, colors and dispersion of the colors. Lots of variables !

I re-read my previous post and see that I had the wrong temp. for maximum heat.

Wishing you a happy, healthy 2020 my friend, you have been missed.
Let's hear more from you.
 
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jerrywh

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Thread starter #20
I have done color case hardening for at least 20 years but never did any with copper inlays until last week. Because I couldn't find any info on it I ran some tests and found that copper will oxidize some but not a lot if it is not given any time to be exposed to the air before it reaches the quench tank. The water level in the quench tank needs to be very close to the top of the tank to achieve this. Aerating the quench is not necessary but will increase the density of the colors and sometimes too much resulting in a gaudy look if you will. Too much color is bad as not enough sometimes. It is my experience that a mixture of 1/3 bone and 2/3 wood charcoal gives the maximum color and brilliance. Adding potassium nitrate to the quench will increase the blues but too much will render almost all blue with little or no variation and the amount is very critical therefore is my advice to omit it entirely. There is a lot of false info on color case hardening mostly by people who never did it but just heard about it from others who never did it. The biggest problem with the process is combating warpage. Most of the demos you see on 1Utube are not up to par and can get you in trouble with warpage.
 

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