Drawing wanted for Charles Butler's Cupel Mold

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bmgold2

bmgold2

Well-known member
Joined
Dec 23, 2013
Messages
298
Location
Pennsylvania
I'm looking for the drawing for the cupel mold that was in Charles Butler's torch assaying book. I had one that I bought from Charles many years ago and lost it. I don't want to buy the $50 book again just to get that drawing.

I found a cupel that I built using his mold and could figure out the little press dimensions from it but it would be MUCH easier if someone else had the drawing from his book.

Here's the cupel I made:

mini cupel.jpg

The cupel measured 1/2" O.D. and 7/16" high with a 3/8" I.D. that is 3/16" deep

Anyone that has his book with the plans could send me a PM or even just tell me some more of the dimensions if you don't want to post them online.

The cupels were to be made from bone ash that was moistened with a little (very little) bit of a mixture containing 1 TBS Glue, 2 TBS Sugar, and 1 Cup of water. I have also used sifted wood ashes or cement as a substitute for the bone ash. These tiny cupels were for the torch assays that used (I think) 1/4 tsp of ore. It might have been even less than that. The ore and flux were fired in a hollowed out piece of charcoal and the little lead bead was cupelled in this tiny, homemade cupel. I never got it to work real well but did get tiny little beads of gold from some tests but needed to get a very small tip for my torch to keep from vaporizing the gold or melting the cupel.

Thanks in advance,
bmgold2

P.S. I'll figure it out on my own if nobody can provide the drawing or any dimensions but I figured someone on this forum probably has that book.
 
There were posts on making crucibles, melting dishes, and cupels, I also remember several types of molds, some were press molds, I do not remember in which topics these were but they should not be too hard to find with the forum search.

I have a question why is your bone ash cupel black, burnt animal bones are white,and the cupels I made turn out white.

Why would you use charcoal in a bone ash cupel? Charcoal will reduce metals or oxides of metals, when you cupel you are trying to get the metals oxidized so the oxidized base metal is absorbed into the bone ash, using carbon would tend to defeat the purpose of the cupel.

Sugar will also act as a reducer, are you actually trying to make cupels or are you just trying to make a small melting dish?
 
Thanks Butcher,

The cupel I found was probably made from unwashed ashes so it probably did have some charcoal. I hadn't thought of that. Might explain some of the problems I had with them. As far as the sugar, I don't know. I was using the formula that was in the torch assay book.

I'll do some more searching and see if I can find any messages on press molds. The only ones I found so far where about using bone ash, burnt bone meal, wood ashes, cement, and even drywall. I have been thinking of making a bigger mold than what the plans showed and maybe use a piece of PVC pipe for the mold.

I'll let everyone know what I come up with. I'd still like to find those original plans for Butler's mold.

Bmgold2
 
I just drew up the cupel mold as I remember it. I'm not sure about the length and the position of the undercut that determines the height of the finished cupel. I doubled the length of the finished cupel to allow room for compressing the mixture.

Anyway, without any dimensions, here's what I am planning. The basic idea is to hold the piston in the upper position and ram it into a container of bone ash or whatever you decide to use and then, with the base on a solid surface, pound the upper part of the piston to compress the cupel. Then, the piston if pressed down which pushes the cupel out. A bag partially filled with water is used to cushion the fresh cupels as they fall then they are carefully set aside to dry.

cupel mold.jpg

I've got a few more places to look for my original, bought cupel mold before I try to build a new one. Besides, it's cold in my shop.

I did search for other messages about making cupels and crucibles and here's what I found. Not exactly what I am looking for but some interesting ideas.

http://goldrefiningforum.com/~goldrefi/phpBB3/viewtopic.php?f=40&t=13173

http://goldrefiningforum.com/~goldrefi/phpBB3/viewtopic.php?f=40&t=12894

The video in the last link had a real good idea for a very simple bellows shown at the end.
[youtube]http://www.youtube.com/watch?v=E3my6-nxFjM[/youtube]

bmgold2
 
For anyone that cares, here's my Mini Cupel Mold drawing with the dimensions. I had to search Google to figure out how to put the dimensions in the drawing and position them in a readable way.

mini cupel plans.jpg

This probably isn't exactly the same as the one in the book but it is as close as I can remember and calculate. Like I said above, the only part I'm not real sure about is the undercut. It might need changed to get enough (but not too much) material in the mold to allow compressing it.

One more note. I think I remember Charles Butler suggesting that the cupels could be microwaved for a minute or so to speed drying but I could be wrong. They have to be dry and I think preheated before using them and when freshly made, they are real fragile and will break easily. Once they dry, they can be handled without so much care.

bmgold2
 
This is from one of my old fire assaying books - Fulton and Sharwood. You can rotate the image in Adobe Reader - view/rotate clockwise.

Here's more info from Bugbee. You can download the Bugbee book from the gear icon at the top right.
http://books.google.com/books?id=mQtZAAAAYAAJ&pg=PA53&dq=making+cupels+intitle:fire+intitle:assaying&hl=en&sa=X&ei=xvzKUsWMGePy2QXZjoDADw&ved=0CEUQ6AEwAA#v=onepage&q=making%20cupels%20intitle%3Afire%20intitle%3Aassaying&f=false
 

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goldsilverpro said:
This is from one of my old fire assaying books - Fulton and Sharwood. You can rotate the image in Adobe Reader - view/rotate clockwise.

Here's more info from Bugbee. You can download the Bugbee book from the gear icon at the top right.
http://books.google.com/books?id=mQtZAAAAYAAJ&pg=PA53&dq=making+cupels+intitle:fire+intitle:assaying&hl=en&sa=X&ei=xvzKUsWMGePy2QXZjoDADw&ved=0CEUQ6AEwAA#v=onepage&q=making%20cupels%20intitle%3Afire%20intitle%3Aassaying&f=false
Click to expand...

EDIT : The attachment didn't quote. I'm talking about the attachment from message above.

Thanks GSP, the hand cupel mold from your scan looks much easier to make than the one I was planning and is bigger although I suppose it could be scaled down if you wanted to. The absorption of PM's was something I hadn't thought about. When dealing with tiny amounts, like Butler's torch assays, even the 1.5 to 1.8 percent could make a difference. Using substitutes like the wood ashes I tried may have left the cupels absorb enough gold to cause false negatives. Now I wonder if my old experiments were working better than I thought up until the cupelling step.

I was looking for my bought cupel mold and didn't find it yet but I did find the video I bought from Charles Butler on his torch assaying and will watch it later tonight if I can.

bmgold2
 
I found my book with the original cupel mold in it. I got a crude hand-drawn plan for that mold. The one in the book was much nicer drawn but the dimensions are here in case anyone wants to make one. My guess on the drawing was close but not exact. I still didn't find the one I bought from Charles but it might turn up someday.

cupel mold drawing.jpg
 
hi i am new to the forum and am a friend of chucks and have taken his assay class...the amount of ore used in the torch assay process is 1/20 th of a teaspoon to 1/4 tsp flux but 3 gram samples can be run by pouring off the slag and combining your lead beads ...you are using too hot a flame when cupeling and one needs to direct the oxygen rich flame around the perimeter of the cupel in slow circles not directly on the bead...as far as cupels go i have found it is much easier to purchase them as chuck has also...they are available under torch assay supplies on e bay...this is a fast and cheap method of determining ones values in the field or lab and i have used it for over 20 years...i have the original cupel drawing if you still want it...it shows to case harden and polish the bore as well as to case harden and polish the end of the plunger....hope this helps...happy trails
 
bughole bailey said:
hi i am new to the forum and am a friend of chucks and have taken his assay class...the amount of ore used in the torch assay process is 1/20 th of a teaspoon to 1/4 tsp flux but 3 gram samples can be run by pouring off the slag and combining your lead beads ...you are using too hot a flame when cupeling and one needs to direct the oxygen rich flame around the perimeter of the cupel in slow circles not directly on the bead...as far as cupels go i have found it is much easier to purchase them as chuck has also...they are available under torch assay supplies on e bay...this is a fast and cheap method of determining ones values in the field or lab and i have used it for over 20 years...i have the original cupel drawing if you still want it...it shows to case harden and polish the bore as well as to case harden and polish the end of the plunger....hope this helps...happy trails
Click to expand...

THANKS for that bit of advice. I did find the original book I bought years ago so I don't need that drawing any more. Just to be clear, you ARE saying that you (I) should be using a "too hot flame" right? Like an oxidising flame? The part about NOT heating the bead directly should help a lot if I try it again. I did try using a MAPP gas torch (burning propane) to cupel a small piece of lead from a split-shot sinker but it didn't work. The oxy-acetylene torch with a tiny tip on it worked much faster. What type of torch did/do you use in the field?

I'm glad to see there is someone who has used the torch assay. I still don't have it figured out but some of my original problem was not using silver-free lead or litharge. Many of my attempts ended in silver colored buttons which means either the lead was not all removed or there was silver in the lead already or the ore I was testing contained silver. Since I didn't keep good records of exactly what I tried, I don't know which was the real reason.
 

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