Author Topic: Quenching color case hardening with air bubbles  (Read 13867 times)

holzwurm

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Quenching color case hardening with air bubbles
« on: January 22, 2012, 11:17:08 PM »
I'm relearning what I knew about coloring lock parts. I came across an article by a Gent who has an air line in the bottom of his quenching container and turns on the air so the water has lots of bubbles in it when the crucible and lock parts are dumped in the water.

Why  ???

Offline smart dog

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Re: Quenching color case hardening with air bubbles
« Reply #1 on: January 23, 2012, 12:02:25 AM »
Hi Holzwurm,
I believe it is done to add nitrogen to the water, which enhances the colors particularly the blue tones.  The bubbles may also affect the color pattern.

dave
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Offline kutter

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Re: Quenching color case hardening with air bubbles
« Reply #2 on: January 23, 2012, 02:21:49 AM »
We added the air bubble thing to the quench and got nothing for it. Tried many different approaches and found it neither enhanced nor diminished what we had already achieved, so we deleted it.

But,,others have found it to be of great use.
Just one of the many reasons the process can be so simple yet so fickle.
So many little variables that must all come together  for the right results.
« Last Edit: January 23, 2012, 07:17:21 AM by kutter »

Rasch Chronicles

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Re: Quenching color case hardening with air bubbles
« Reply #3 on: January 23, 2012, 07:15:49 AM »
Fellows,

I remember reading a treatise on CCH and they mentioned the use of airstones to agitate the water. Their contention was that as the air bubbles struck the steam coated metal it created temperature differentials that helped create the oxide colors.

Best Regards,
Albert “Afghanus” Rasch
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Offline P.W.Berkuta

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Re: Quenching color case hardening with air bubbles
« Reply #4 on: January 23, 2012, 07:32:07 AM »
I'm relearning what I knew about coloring lock parts. I came across an article by a Gent who has an air line in the bottom of his quenching container and turns on the air so the water has lots of bubbles in it when the crucible and lock parts are dumped in the water.

Why  ???
It's "hit or miss" you decide - if it works for you then you win -- but it's more trouble then it is worth - send it to the professionals pay your money and get the look you want ;).
"The person who says it cannot be done should not interrupt the person who is doing it." - Chinese proverb

ddoyle

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Re: Quenching color case hardening with air bubbles
« Reply #5 on: January 23, 2012, 08:45:08 AM »
Quote
but it's more trouble then it is worth - send it to the professionals pay your money and get the look you want

So are 99% of the other 'chores' discussed on this forum!   

 

Offline kutter

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Re: Quenching color case hardening with air bubbles
« Reply #6 on: January 23, 2012, 11:52:06 PM »
If you don't like doing things for yourself,,you end up watching TV or hanging out at the Mall. I've seen it happen! :)

[quote ]
...when the crucible and lock parts are dumped in the water.

[/quote]
I just noted this in your original post,, dumping the crucible itself into the quench along with the contents.
Maybe just worded wrong.

Again, perhaps some have done it that way, but I've never seen it so. We always turned the box over above the quench and allowed the contents (parts and char) to fall into the quench.

Our parts were individually suspended from wires attached to the bottom (the 'top' on the inverted box over the quench tank). The parts and char dumped into the quench,,the parts only sinking a little more than 1/2 way because of the wires they were attached to.
After a '5' count, a pin through the box and wires was pulled with a pliers and the parts then dropped the rest of the way into the tank and onto the bed of char on the bottom.
Just the way we did it. Not necessarily 'the' way to do it.

The distance it falls, depth of the quench, temp of the quench will effect the colors and pattern too as will the amount of time between upcapping the box and actually dumping it.
Our quench was preheated to 90F. No added chemicles, no  aggitation.

hammer

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Re: Quenching color case hardening with air bubbles
« Reply #7 on: January 24, 2012, 12:50:11 AM »
Haven't done it myself (yet) but this guy has:

http://www.vintageshotgun.com/index.php/2011/09/05/new-cch-quench-tank/

He is THE authority on the restoration of antique shotguns; colour case hardening, blueing, damascus browning, blacking, stock refinishing, etc.   

Worth a look.

Hammer

Offline JCKelly

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Re: Quenching color case hardening with air bubbles
« Reply #8 on: January 25, 2012, 06:32:18 AM »
I believe something like the practice used by Doug Turnbull is what Oscar Caddy published in
The Double Gun Journal, Vol 7, Issue 4, 1996 and Vol 8, Issue 1, 1997. Involves the use of some real wood charcoal mixed with bone charcoal. It is the calcium phosphate in the bone charcoal which gives the reasonably durable case colors. Bubbles in the water, or sodium nitrate, give thin "temper colors" which do not last long.

Michael

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Re: Quenching color case hardening with air bubbles
« Reply #9 on: January 25, 2012, 03:06:09 PM »
Just a thought----

As it was brought to my attention by a Master gunsmith: the purpose is to harden the parts, the color is secondary.

Offline Dphariss

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Re: Quenching color case hardening with air bubbles
« Reply #10 on: January 25, 2012, 07:54:38 PM »
I believe something like the practice used by Doug Turnbull is what Oscar Caddy published in
The Double Gun Journal, Vol 7, Issue 4, 1996 and Vol 8, Issue 1, 1997. Involves the use of some real wood charcoal mixed with bone charcoal. It is the calcium phosphate in the bone charcoal which gives the reasonably durable case colors. Bubbles in the water, or sodium nitrate, give thin "temper colors" which do not last long.

A friend who does charcoal hardening for a living tells me that the ratio of bone to wood charcoal is the key in not damaging the finished surface. It seems that all wood or all bone gets pretty ugly.

Dan
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Offline Dphariss

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Re: Quenching color case hardening with air bubbles
« Reply #11 on: January 25, 2012, 07:59:51 PM »
Just a thought----

As it was brought to my attention by a Master gunsmith: the purpose is to harden the parts, the color is secondary.

But properly done with charcoal color is unavoidable. It comes from the pack.

Dan
« Last Edit: January 25, 2012, 11:21:18 PM by Dphariss »
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Offline Jim Kibler

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Re: Quenching color case hardening with air bubbles
« Reply #12 on: January 25, 2012, 09:35:18 PM »
You can certainly get a good case and no colors with charcoal.  I use a 50 / 50 mix of wood an bone.  Sometimes I get nice colors other times it is just basically a gray color.  No scale etc. on the gray ones either.  The case seems fine as well.  As I've mentioned before, I remove any colors that might have formed, so it means nothing to me whether they are there or not.

Offline FlintFan

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Re: Quenching color case hardening with air bubbles
« Reply #13 on: January 25, 2012, 09:42:02 PM »
Quote
A friend who does charcoal hardening for a living tells me that the ratio of bone to wood charcoal is the key in not damaging the finished surface. It seems that all wood or all bone gets pretty ugly.

Dan

I have found that the ratio of bone to wood plays a huge role in the outcome.  Modifying the ratio is very important when trying to copy the process used by various makers.  I have found "in general" that English guns use a much larger ratio of bone to wood.  I have used ratios of 3:1 bone to wood when replicating the colors of certain English double guns.  Others have found a higher (2:1 up 6:1) wood to bone ratio is helpful when replicating colors on certain American guns.  I have found that using a higher bone to wood ratio gives a larger colored area that has other colors mottled within that area.  A higher wood ratio seems to give more areas of color and no color intermixed together, think of a Colt revolver frame.  Again these are generalities, and many other examples and exceptions can be found in the gun making regions of the world.  
« Last Edit: January 25, 2012, 09:42:54 PM by FlintFan »

Offline Acer Saccharum

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Re: Quenching color case hardening with air bubbles
« Reply #14 on: January 26, 2012, 01:33:18 AM »
I've heard that wrapping the parts in iron wire retains some charcoal or air near the parts so that the quench does not hit the part all at the same time. Gives a bit of delay in other words. Then you get the mottled effect.

I've done the wire wrap thing, but not enough to say conclusively whether it has a big effect or not.

Tom

Not a very good view of the colors, but they are mottled.

« Last Edit: January 26, 2012, 01:35:12 AM by Acer Saccharum »
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Offline kutter

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Re: Quenching color case hardening with air bubbles
« Reply #15 on: January 27, 2012, 12:17:29 AM »
2:1 and 3:1 were the only ratios we used. This was at Turnbull's. From that we did all the differnt parts and mfg'rs patterns & colors.

Wood & bone char was hand mixed in large quantity outside on a windy day to blow the fine dusty mat'l away. That stuff would ruin the process.
Also the quantity that was going to be used for that day was heated in a metal box with a loose cover for a couple of hours before use to drive off any moisture. Simply setting it on top of the ovens while they heated up was sufficient. Same was done with the bone char prior to use in charcoal (carbonia ) blueing.
Moisture driven out of the char while packed tightly in the pot w/the parts in the oven will some times put a haze (for lack of a better word) on the steel as it is driven out.
Something like the haze on clean steel when you heat it with a propane torch and moisture appears then vanishes from the surface.

They may do things differently now,,this was a while back.

holzwurm

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Re: Quenching color case hardening with air bubbles
« Reply #16 on: January 27, 2012, 02:31:12 AM »
thanks for all the reply's based on about a 100 years of experience.  :)

I did  my first try today on a lock plate, hammer and top jaw. I probably did several things wrong but I did get color! Mostly a mottled grey with a few lighter places where the lighter color showed though.  The hammer showed more variations and a file will just slide off.

My oven is pretty small and the temp was steady at 1450 but I did notice it bumped up to 1500 a couple of times and I had to adjust it down. My ratio was 2:1 wood/bone char. My container is 4" round steel tube with a welded bottom and a cap that I can remove to dump the mix. I'll try to post a few pictures

I did note that when I removed the cap for the dump the packing had reduced by about 1 inch from the top. When I set thing up it was packed and level with the top.

It was pretty much a mess when I started to clean up. One lives and learns ;D

Thanks for all your reply's

Jerry 

Offline smart dog

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Re: Quenching color case hardening with air bubbles
« Reply #17 on: January 27, 2012, 03:23:00 AM »
Hi Jerry,
I have a set up much like yours although my oven is programmable so that I can set up different heating regimes.  Let me make a couple of suggestions.  First, see if you can make or buy a retangular frame shaped like a baking pan with a lid.  When you use a pipe that opens on the end, you end up pouring out the pack as a stream.  If the parts are exposed to air before hitting the water, you risk getting what is called "flash", which results in a dull grey color.  The parts will be hardened correctly but the colors will be gone.  With a rectangular pan, you remove the lid and then flip the pan over the water quickly so the entire contents fall out in a single lump.  You cannot avoid making a big explosive splash and subsequent mess so learn to live with it.  Your temp may be on the high side for really vivid colors, however, I like to heat to 1600 for the lock internals.  I only use temps (around 1425) for lockplates, cocks, and frizzens.  I usually heat soak for 90 minutes at least.  I have consistently good results with those methods.

dave   
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Offline Dphariss

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Re: Quenching color case hardening with air bubbles
« Reply #18 on: January 27, 2012, 04:38:02 AM »
thanks for all the reply's based on about a 100 years of experience.  :)

I did  my first try today on a lock plate, hammer and top jaw. I probably did several things wrong but I did get color! Mostly a mottled grey with a few lighter places where the lighter color showed though.  The hammer showed more variations and a file will just slide off.

My oven is pretty small and the temp was steady at 1450 but I did notice it bumped up to 1500 a couple of times and I had to adjust it down. My ratio was 2:1 wood/bone char. My container is 4" round steel tube with a welded bottom and a cap that I can remove to dump the mix. I'll try to post a few pictures

I did note that when I removed the cap for the dump the packing had reduced by about 1 inch from the top. When I set thing up it was packed and level with the top.

It was pretty much a mess when I started to clean up. One lives and learns ;D

Thanks for all your reply's

Jerry 

Shorten the distance from the water to the container. 
Dan
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Offline kutter

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Re: Quenching color case hardening with air bubbles
« Reply #19 on: January 27, 2012, 06:33:45 AM »
What ever container you're using, when you 'pack' the parts,,every surface must be in contact with the char.
But you do not want to compact it to the point of crushing the char into dust doing it.

As you place the parts in and start adding char around them,,bounce and rock the container to settle the contents. We made a $#*! of a racket packing the boxes up as it was done on a steel table.

An inch of char surrounding each part and extension off of a part is best. You can get away with a little less but not much.
Our boxes were a couple different sizes. But they were both shaped like a flower box looking from the end. Wider at the top than the bottom by just a bit,, the smaller box about 14" long, height about 7".
In that small box we'd do a complete shotgun frame w/ forend, top lever, trigger plate (installed on frame) and have room for a Colt SAA frame w/ gate  & the hammer.
No spacers or shields on the parts. No anti-warping braces.

The box's cover was removed while the box was still in the oven. A quick series of movements to open the furnace, remove the cover and put it aside, change implements (forks) and now hook onto the box itself.
Lift it out of the furnace, walk w/it over to the quench tank, set it on the support, close the shield, and overturn the box.
Wait the 5 count and pull the pin holding parts on the wires so they can sink to the bottom.
About 12"+ drop from inverted box to quench surface.  Box was always overturned from the same distance above the quench as it was rested on a support.


A steel shield was pulled into place just before to protect from steam and splatter and an outside vent took most of it out. But dangerous for sure if you're standing there unprotected.

The same cadence was carried out each and every time to get uniform results. Changing anything from beginning to end once you have a routine that yields good results will most likely alter those. Sometimes it can be the smallest of changes.

Again it's not the only way to it, it was the way we did it and got the results we did.

Offline 44-henry

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Re: Quenching color case hardening with air bubbles
« Reply #20 on: January 27, 2012, 11:09:52 PM »
One of the more important things to remember is do whatever possible to limit air exposure between the time the parts leave the crucible and when they hit the quench. Aside from that it is a pretty simple process. I have pretty much settled on a 50/50 mix of wood to bone, clean hand polished parts, and temperatures about 1450 degrees F. Most of my color casehardening I do in the winter and I pack the quench tank with ice to get the water as cold as possible. I do often run air in the quench tank, but I generally shut it off before quenching. I also have much more consistent results if I wrap the parts with clean iron wire before packing them. Colors are pretty reliable with this process in any event.

Also, the fellow that Hammer  referenced above from England got most of his information from these threads and personal correspondence following the discussions we had on this subject several years ago. He does a nice job, but if you ask me his quenching temperatures are definitely on the low end of acceptable. Great colors do occur at lower temperatures, even those under critical temperature, but you don't get hardened parts at this point. Unfortunately getting into temperature ranges that are really effective for casehardening generally leaves very few colors behind no matter what your process is.
« Last Edit: January 27, 2012, 11:17:35 PM by 44-henry »

Wayne Single Shot

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Re: Quenching color case hardening with air bubbles
« Reply #21 on: March 15, 2013, 11:10:18 PM »
2:1 and 3:1 were the only ratios we used. This was at Turnbull's. From that we did all the differnt parts and mfg'rs patterns & colors.

Wood & bone char was hand mixed in large quantity outside on a windy day to blow the fine dusty mat'l away. That stuff would ruin the process.

2:1 & 3:1 Is that 2&3 wood to 1 bone char? Also did you buy the charcoals or make your own? If you made your own, from what types of bone and wood? Or where was it bought? Newbie trying to learn. Thanks

Offline kutter

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Re: Quenching color case hardening with air bubbles
« Reply #22 on: March 16, 2013, 02:06:21 AM »
2:1 and 3:1 were the only ratios we used. This was at Turnbull's. From that we did all the differnt parts and mfg'rs patterns & colors.

Wood & bone char was hand mixed in large quantity outside on a windy day to blow the fine dusty mat'l away. That stuff would ruin the process.

2:1 & 3:1 Is that 2&3 wood to 1 bone char? Also did you buy the charcoals or make your own? If you made your own, from what types of bone and wood? Or where was it bought? Newbie trying to learn. Thanks

Yes,,sorry,,Wood char to Bone char.
All purchased materials.
The Bone Char right from Ebonex Corp in Michigan.
The Wood charcoal was a bagged and delivered product to, but I don't recall the mfg now.
Both received in the right size/mesh grade for use.

Just the ratio  mixing with a coal shovel on a breezy day to rid it of the fine dust was all that was necessary then.

Always a heavy lifting day when the tractor trailer deliverys showed up.

Offline Acer Saccharum

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Re: Quenching color case hardening with air bubbles
« Reply #23 on: March 16, 2013, 05:05:50 AM »
I always got fair colors with just charcoal, never did the bone charcoal in the mix. I thought that a higher heat with charcoal the colors tended toward gray, while lower temps gave better colors.
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Wayne Single Shot

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Re: Quenching color case hardening with air bubbles
« Reply #24 on: March 16, 2013, 10:57:33 PM »
Thanks for the responses from kutter & Acer Saccharum.

Another idea that I have been mulling around is that someone in this thread mentioned "Bubbles in the water, or sodium nitrate, give thin "temper colors" which do not last long." I heard it said both ways that UV rays eventually destroy the colors and some say their colors don't get destroyed.

So I wonder if the folks using bubbles, etc are the ones having the issue of color loss, and are the folks not using the bubbles the ones that that don't have as much color loss.

I've seen claims on both sides of the aisle here; and I don't doubt anyone’s claims. I'm just trying to determine if there is an explanation for the differing results folks are experiencing. Looking forward to the responses and thoughts on this. Thanks again.
« Last Edit: March 16, 2013, 11:09:31 PM by Wayne Single Shot »