Case hardening and case coloring

[flatsguide]

I have part 1 of Oscar Gaddey's , Color Case a Hardening article but I can not find part 2. Does anyone have a link to part 2?
Thanks, Richard

[smart dog]

Hi Jim,
Thank you for that explanation about the effects of heat treating on grain.  That helps me understand what is going on a great deal.  I am usually rehardening frizzens that I annealed to file and polish or to engrave.  Then I always case harden them and temper.  I've done this for locks from almost every commercial maker and find that case hardening improved L&R frizzens the most by far.  I am not impressed with the quality of their castings and I always have to do more work cleaning up, shaping, and tuning L&R locks than any other commercial maker but once worked over they are some of the best sparking locks I've seen.   

dave

[RAT]

Question... why would anyone need to harden a patchbox?

Or a buttplate or side plate for that matter. I understand that some want the colors strictly for a modern aesthetic, put I think it looks out of place. Just a personal opinion.

[smart dog]

Hi RAT,
Actually, color cased buttplates and trigger guards were common on many firearms from the early 19th century until the end on the muzzleloader era.  So depending on what you are trying to achieve, color casing can be appropriate and very attractive.  It is not likely to be correct for an American longrifle, although I believe the Harpers ferry rifles had case hardened locks on which colors were left. An advantage of case hardening with respect to buttplates, patch boxes, sideplates, and trigger guards, is that it provides a lot of corrosion resistance if the part is to be polished rather than blued or browned. That may not be important for most folks but if you are engraving a firearm and want a polished steel background to show the artwork, the corrosion resistance from hardening is a plus.

dave

dave

[Joe S.]

I don't really care if the parts end up with color or not and probably shoot more for case hardened grey.This finish will handle the damp winter weather more than carded back blue ect.I think case hardening is more period correct for what I'm building and seen plenty of rust brown finish to know that not for me.As far as the patch box goes I'm just trying to get all the metal parts to match in color or at least close.Just my personal preference.

[flatsguide]

Hi Jim,
Thanks for explaining some of the benefits of case hardening re grain structure. I will definitely put that advise to work. BTW, do you have any Links to part 2 of O. Gaddey's article on case coloring?
Thanks Richard

[JCKelly]

flats - send me an email off-line & will send you a pdf of 2

[flatsguide]

Email sent...Thanks Jim

[David Rase]

Richard,
While you are reading you might want to read this blog on the Marlin Firearms Collectors Association.  There's 31 pages.  It is way more user friendly with real life trial and error color case hardening attempts.   
http://www.marlin-collectors.com/forum/viewtopic.php?f=5&t=3732&st=0&sk=t&sd=a
David

[JCKelly]

Marlin post valuable.
I like Geddy, but then I am accustomed to detailed metallurgal explanations. Scanned Geddy again & saw things I hadn't noticed before.
Bone Charcoal is still available from the Ebonex Corp, Melvindale, Michigan. It is the calcium phosphate in bone charcoal that gives the colors.
I hadn't thought of volatile compounds coming off of new charcoal, but it does make sense. As I vaguely recall, commercial charcoal is processed no hotter than 650 - 700F. Char the wood too hot, and the creosote leaves. One needs creosote in charcoal used for black gunpowder in order to get a "moist burning powder"
I digress.
One must dump the parts directly from the carburizing box into the water, right at the water surface as any air touching the parts will dim the colors.

I personally would leave cyanide out of the mix. It will affect the colors but is not the best substance to handle & keep around the shop.
Before Our Gov't Helped us with Safety, we used to caseharden in a molten 30% sodium cyanide bath at around 1600F. Most of us survived just fine, evil & ignorant as we were. We did not heat our sandwiches around the cyanide pot.

If for some reason you plan to use cyanide for heat treating it is very important that you get your information from old sources.

Do not, on your life, believe the idiocy currently found on the web.

Your Unenlightened Great-grandfathers knew how to deal with the stuff but few today have a clue. Get thee a used copy of the ASM Handbook, preferably from 1939, although the 1948 edition is a good one. Try abebooks dot com.

You might gather that I am an actual metallurgist, graduated whilst JFK was chasing Marilyn. 

[flatsguide]

David, thanks for that link. I read 10 pages before I crashed last night with information overload. I think Jim Kelly above contributed to that discussion. It seems that keeping the temp no higher than 1350 F then dropping down to 1100F prior to quench reduces warpage to a neglagable amount. Smart dog mentioned that a lot of firearms of the early 19th century had case hardened BP's and trigger guards. I would make up some sacrificial butt plates and trigger guards to test first before zi would use good ones.
Jim, good info...Looking forward to seeing Gaddeys explanation of CCH. Thanks a lot.

I really appreciate all the help and I sure will share all my finding when I get going on this.
Regards, Richard

[Mark Elliott]

David, thanks for that link. I read 10 pages before I crashed last night with information overload. I think Jim Kelly above contributed to that discussion. It seems that keeping the temp no higher than 1350 F then dropping down to 1100F prior to quench reduces warpage to a neglagable amount. Smart dog mentioned that a lot of firearms of the early 19th century had case hardened BP's and trigger guards. I would make up some sacrificial butt plates and trigger guards to test first before zi would use good ones.
Jim, good info...Looking forward to seeing Gaddeys explanation of CCH. Thanks a lot.

I really appreciate all the help and I sure will share all my finding when I get going on this.
Regards, Richard

If you want to do tests,  I wouldn't waste your time making actual parts.   Just buy some 1/8" x 1" 1018 and cut it into 4-5" strips and polish one side.   

[jerrywh]

 If you keep the temp down to 1350° for the soak and then quench at 1100° you will not get hardening. You will only get color so you will defeat your entire purpose of preserving the engraving and integrity of the parts. I have seen this many times and it is a copout way of doing the job.
 Grain structure may be interesting to know but is irrelevant as far as case hardening goes. Because if you want case hardened parts what you end up with is what it is. You have no choice.
 I don't know why some people want to make this subject so complicated. The process is real simple. Personally I don't think the ingredients of the pack have as much to do with the color as the bubbles in the quench do. I have seen dozens of different color effects out of plain wood charcoal. You can change the colors by fooling with the temp of the water and adding potassium nitrate to the water. It doesn't take much potassium nitrate to get a solid blue color. One thing I can say for sure is you will never produce two objects the same. 

[David Rase]

I don't know why some people want to make this subject so complicated. The process is real simple.  One thing I can say for sure is you will never produce two objects the same. 

Amen to that Jerry!
David

[smart dog]

Hi,
I second Jerry and Dave!!  The object of case hardening - is hardening.  Below 1350 degrees and you probably will not harden parts properly or have a deep case.  For me, colors are secondary to proper hardening and tempering.  Jerry also mentioned adding potassium nitrate to the quench water.  I believe it is the nitrogen that gives the blue colors and you can add more nitrogen (from the air)to the water by bubbling or stirring it before quenching.  Adding potassium nitrate also works for that purpose.  Consider the two locks on guns I built shown below.  In both cases the lockplates and flintcocks were cased at 1575 degrees for 90 minutes and then quenched.  I was not seeking any mottled colors but I added 1/2 cup of potassium nitrate to about 15 gallons of water for the quench.  The result is a blue-greenish tint to the metal that is translucent and has a really nice appearance.  Tempering the parts afterward at 490 degrees for 1 hour darkens the color by adding a slight bronze tint.  The result really looks nice as any folks who saw my "Star of Bethlehem" at Dixon's this year can attest.  However, it is very important that any part to be colored during heat treating must have well polished surfaces.  The sand beaded surfaces on commercial locks has be polished bright before case hardening.  Flatsguide, I've noted quite a few English-made guns from the early 19th century with color case-hardened trigger guards and butt plates. I've not seen any American made guns done that way.  Keep in mind, the color from case hardening is not very durable and is easily polished off and fades over time. 

dave
   

[flatsguide]

Jerry, Smart Dog, you are right that you will not get hardening at 1100 degree quench. I know you need to reach the critical temp prior to quenching to get a hard part,if it has the carbon content. My head was wrapped around case COLORING and no warpage, that I lost track of the real reason for case hardening. Thanks for the reality check.
Smart Dog, that is a smart looking rifle and I do like the subtle colors that I see on your riflemuch more than the gaudy colors.
Mark, you got that right, no way would I waste time and material .
Thanks Guys

[flatsguide]

This is an interesting read.

http://www.doubleguncraft.com/uploads/PDFs/GunCraft_Book.pdf

[jerrywh]

A few years ago I did a tutorial on this forum and said that wrapping wire around a piece or placing other pieces of metal close to the parts to be hardened would give better colors.
 In my opinion it is not that it causes slower cooling but rather the fact that it traps the steam bubbles close to the metal that enhances the colors. However the two probably are  simultaneous. I once wrapped a lock with iron wire and after quenching it showed blue steaks where each wire crossed the lock plate.

[Daryl]

What D.Taylor Sapergia described is pretty much the way it is properly done.

James, Thank you and thanks for the photos.

Regards, Richard

The nice thing about a forum such as this, is that everyone is entitled to their own silly opinions.

[flatsguide]

And the poor things about a good forum like this are guys that post negative non- constructive input. Smiley faces notwithstanding.

[smart dog]

Hi Richard,
I think Daryl was needling his brother, Taylor. As I am sure you are aware, Taylor is one of the finest gunmakers anywhere.  We all benefit greatly from his input.  I also know that Daryl is pretty fond of Taylor and his work.
dave

[flatsguide]

Dave, I did not know that. Thank you for clearing that up. My apologies to Daryl. As to Taylor  I agree his work is some of the finest.
Regards, Richard

[Daryl]

That's OK Richard - not taken too hard.

[flatsguide]

My profound apologies Daryl.
Regards, Richard

[David Rase]

Today I case color hardened some underhammer castings I purchased from Muzzleloader Builders Supply in August.  Because of the long upper and lower tang and influence from this thread I lowered my temperature to 1400 degrees to lessen the risk of warpage.  I did bolt the upper and lower tangs together using a spacer in the rear.  I used a mixture of 2 -1 wood - bone charcoal and once up to temperature I left them in the oven for 1 hour.  I quenched them in my 32 gallon plastic trash can and then tempered them at 400 degrees for 1 hour.
As you can see, where the metal is thick or heavy I got lots of blue at 1400 degrees.  On thin areas and light pieces like the screw heads, mostly grey.  I don't know if the heavier parts absorb the heat better or the smaller parts over heated.  The thin areas on the edges of the trigger plate next to the cut out for the hammer and trigger also remained grey.  In the past, when I went up to 1500 degrees I got color in my screws so I am assuming that the screws and thin areas are not getting up to temperature.    
If you look at the trigger you can see more grey where there is less mass.  
I wonder if I could of got a more even color distribution if I had blocked or wrapped wire around the thin areas and screws and created more mass.
David