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.RC.
09-20-2012, 09:15 PM
Have got most of the ingredients for making up a pack case hardening mix, but the recipe only says

Hardwood charcoal 85%
Sodium Carbonate 2%
Calcium Carbonate 3%
Barium Carbonate 10%

Another recipe is similar but gives volumes by parts

So would the percentages be by volume of each ingredient or weight of each ingredient?

Jaakko Fagerlund
09-20-2012, 11:54 PM
They are solids and thus measured in weight, as the volume measurement would depend on the particle size.

CCWKen
09-20-2012, 11:55 PM
Mixing can be by weight or volume. The formula should state any specifics but it shouldn't make any difference for your application as long as you stick with the same method of measurement throughout. If you mix 100 pounds or 100 cups, the formula is the same.

Evan
09-21-2012, 02:38 AM
They are solids and thus measured in weight, as the volume measurement would depend on the particle size.

Actually, particle size only makes a difference if there is a range of particle sizes. If a solid of all the same material is of a single particle size the actual size makes makes no difference to the quantity in a container as long as the container is significantly larger than the particles.

To simplify that, a cubic metre of 1cm gravel has the same mass as a cubic metre of 2 cm gravel.

Another way to think of it is what if all the gravel were cubes? The size of the cubes would make no difference. Same if they are marbles. The ratio of space to matter stays the same regardless of the size of the particles.

.RC.
09-21-2012, 02:54 AM
Remember charcoal is mostly air... The rest are fine solids...

lazlo
09-21-2012, 09:59 AM
Could you tell us about the formula? That's obviously a color casehardening formula -- calcium carbonate is the active ingredient in bone char that imparts all the colors.

Barium carbonate is a case accelerator, but what does the sodium carbonate (washing soda) do?

Barrington
09-21-2012, 10:26 AM
Maybe this was the OP's source ? but the same recipe appears on page 11 (page13 of the pdf ) of this document:-

Charcoal from New South Wales Species of Timber (http://www.dpi.nsw.gov.au/__data/assets/pdf_file/0004/389722/Charcoal-from-NSW-Species-of-Timber-2nd-Edition.pdf)

- with explanations for the ingredients.

Cheers

.

rkepler
09-21-2012, 10:45 AM
So would the percentages be by volume of each ingredient or weight of each ingredient?

The numbers you have are in line with the recipies I've seen by weight. Many of them also suggest bone charcoal, leather and/or charcoal made from fruit pits.

Most of the recipies suggest dissolving the carbonates in water and soaking the charcoal in the mix, then spreading it out to dry, this for an even distribution of the carbonates in the pack.

09-21-2012, 11:49 AM
Weight. Period.

Sparky_NY
09-21-2012, 12:02 PM
The numbers you have are in line with the recipies I've seen by weight. Many of them also suggest bone charcoal, leather and/or charcoal made from fruit pits.

Most of the recipies suggest dissolving the carbonates in water and soaking the charcoal in the mix, then spreading it out to dry, this for an even distribution of the carbonates in the pack.

Isn't bone charcoal also more commonly known as activated charcoal? I could be way off base with this but it seems to ring a bell.

Jaakko Fagerlund
09-21-2012, 12:08 PM
Actually, particle size only makes a difference if there is a range of particle sizes. If a solid of all the same material is of a single particle size the actual size makes makes no difference to the quantity in a container as long as the container is significantly larger than the particles.

To simplify that, a cubic metre of 1cm gravel has the same mass as a cubic metre of 2 cm gravel.

Another way to think of it is what if all the gravel were cubes? The size of the cubes would make no difference. Same if they are marbles. The ratio of space to matter stays the same regardless of the size of the particles.
Well you don't do anything with those ratios or volumes, unless all the ingredients have the same density.

They are solids -> they are measured by weight.

RWO
09-21-2012, 01:46 PM
Ebonex sells bone charcoal for hardening and bluing: http://www.ebonex.com/b_app.htm#gun
Brownells sells it too: http://www.brownells.com/.aspx/pid=1231/Product/BROWNELLS-HEAT-TREATING-CHARCOAL

RWO

bob_s
09-21-2012, 02:47 PM
Cheaper to use bone meal from home despot. 15#=\$45

lazlo
09-21-2012, 04:14 PM
Isn't bone charcoal also more commonly known as activated charcoal? I could be way off base with this but it seems to ring a bell.

No, activated charcoal is an excellent source of carbon for the pack hardening, but the colors from case hardening come from the calcium carbonate. Bone char is rich in calcium carbonate.

Cheaper to use bone meal from home despot. 15#=\$45

OMG, I can tell you've never tried that! Burning bone meal is the most awful smell on Earth!

You can get bone char (and barium carbonate, for that matter) at most any pottery supply.

Evan
09-21-2012, 04:33 PM
Burning bone meal is the most awful smell on Earth!

A lot like tooth drilling back when dentists used 300 rpm rotary drills with belts. Except worse.

Mike Hunter
09-21-2012, 04:34 PM
I do quite a bit of Color Case hardening, Wood and bone char is all I use...

All that other foolishiness is just that foolishness..

V/R

Mike Hunter
Hunter Restorations

.RC.
09-21-2012, 07:14 PM
Thanks everyone..... Weight it is...

.RC.
11-08-2012, 03:25 AM
Well I mixed a batch by weight, heated to 925C for five hours, then quenched...

Was mild steel when it when in..... Came out at 60HRC after case hardening......

Success.

BigJohnT
11-08-2012, 07:30 AM
What's the procedure for case hardening? Do you put the parts in SS bags with the mix?

John

Jaakko Fagerlund
11-08-2012, 11:40 AM
What's the procedure for case hardening? Do you put the parts in SS bags with the mix?

John
Anything "airtight" is enough. I've used a piece of square structural steel that has had a plate welded at the other end for plug and the other end was just milled straight and a stepped plate was installed on top of it that had a 3 mm hole in it for venting out pressure. The parts were inside about in the "middle" of the tube in every direction, with the case hardening mixture around them. When it was ready to be quenched, I just turned the tube upside down over a cool water bath.

BigJohnT
11-08-2012, 11:58 AM
Jaakko, thanks for the info... I need to get busy building a heat treat oven.

John

.RC.
11-08-2012, 03:21 PM
http://img.photobucket.com/albums/v606/OzRinger/20121028_091931Custom.jpg

http://img.photobucket.com/albums/v606/OzRinger/20121028_092216Custom.jpg

http://img.photobucket.com/albums/v606/OzRinger/20121028_164910Custom.jpg

http://img.photobucket.com/albums/v606/OzRinger/20121028_165503Custom.jpg

BigJohnT
11-08-2012, 06:12 PM
Thanks for the photos... much easier to understand.

John