SULPHIDES

An interesting topic from conversations on the hotglass list and additional information

ORIGINAL QUESTION
"OK - I know there are paperweight and marble makers out there. A "sulphide" as I have always understood it - is actually a type of ceramic, cast and fired - and then encased in glass.
Does anyone KNOW what type of ceramic this is? Porcelain type perhaps?
does anyone have a "sulphide" recipe?

dying of curiosity...."
Cheryl - www.dragonbeads.com

billy@napanet.net (Mary)

I had this in my files. I got it SOMEWHERE on the Internet. Unfortunately,
I don't remember where. I hope it helps.

This recipe comes to me from Roland Butler in issue #5 of Independent Glassblower.
SULFIDE FORMULA

Potash Feldspar 17.6oz
Edgers plastic kaolin 34.8oz
Potters flint 8.0oz
Colemanite 5.2oz
Whiteing 4.0oz
Bentonite 2.4oz
Ball clay 2.6oz
Mix dry and then add enough water to make a plastic putty. Air dry tnd then
fire to cone 5 (2200f)
I haven't tried the recipe so I don't know how it works. It's supposed to have an LEC of 95
Mary Ann

The above recipe would be formed in a mold- as any pressed clay design is formed, and then fired. The picture below is a sulphide mold that came from the St. Clair glassworks (Indiana).

The figure is Franklin Roosevelt. (collection of Cheryl Keggan)
These sulphides were placed in paperweights manufactured by St. Clair.
Thanks to Christina Tanner for the photos. For more on molding and molds
CLICK HERE
<< hi, my name is katie lynch, a student at university of illinois, champaign, in glass and ceramics.. I've been following some of the talks, and was interested in the sulphides discussion.. I know almost nothing about the, and was curious for a langer explanation of how they are used..
>>
Sulphides are a type of ceramic (not glass) object which is inserted into a in a paperweight or marble during manufacture. This is an excellent example -

St.Clair Paperweight - image of the famous American Indian Tecumseh.

the COE of the sulphide has to match the glass pretty closely - or the glass and sulphide will separate - and the whole piece will crack.
-Cheryl - www.dragonbeads.com

Comments from Henry Halem
Some years ago I did some work in this area but not that much and I am not as aware of the chemistry as some that have responded. I believe there is more than one way to skin this cat as more than one glass house produced Sulphides. My recollection is that the clay body I used had Talc in it and was dead white. It was white because that was the color we wanted. I would assume
small percentages of metalic oxides would give you some color as needed and would not change the expansion in any way. Now as far as fitting different expansion glasses is concerned I would think you would need to identify what materials were in the clay batch and fool with the chemicals that had the highest expansions. Clays of the nature that your fooling with probably
have some Whiting (CaO) in them and you may want to fool with that as well as any feldspar that might be in the clay formula. The materials with the highest expansions are in order, Na20, K20, and Ca0. Let me know what you come up with.
Henry

-------------------------Follow-up
I was recently asked to research how paper weight sulphides were made and although paper weights are not my area of expertise I remembered my friend Paul Stankard had done some research in the area when we were at Pilchuck some years ago. Paul was very happy to share his findings. I thought posting it on this site would be a good place for sharing those findings. I'll also post it on my web site.
Henry

White Sulphide Inclusion for paper weights

80 % SiO2 200 mesh
20 % crystal fine powder, same glass as being used. 100 to 200 mesh preferable. Grind in a morter and pestle and mix throughly with the silica.
Gum Arabic

For color add Paradise Paints or Kugler color.

Procedure for preparation: Add enough Gum Arabic solution to make a moldable paste. Press paste into mold and allow to almost dry. While still a bit moist but easily handled remove from mold and put in kiln. Fire to cherry red and cool. When cool remove from kiln and clean any areas that need enhancing. The "sulfide" will not be brittle as the glass will have fused the piece together. After cleaning put into pick-up oven and reheat to cherry red once again. It is now ready to be encapsulated in weight.

The directions for making the "sulfide" was told to me by Paul Stankard. He along with Dwight Lanman did the experiments at Pilchuck some years ago.
Henry

 

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