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Thin disk "vulcanite" beads - first chemistry report
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Posted by: Rosanna Post Reply
01/25/2011, 21:35:15

From the strand pictured below (sold to me as vulcanite trade beads) I tested two random beads, one black and one red, by reflectance infrared (IR) spectroscopy - and they are definitely not natural rubber based polymer. Their "fingerprint" was closest to PVC. I took two others of each color and tried to dissolve them in several solvents. One of the red disks and dissolved completely in MEK (methyl ethyl ketone), proving that it is not vulcanite or any type of crosslinked rubber. However the black disk that went into the MEK was not attacked at all. I will check that one with IR and see what I get.

As I examined the disks more closely I could see that there were different thicknesses, different shades of red, and slightly different diameters. At this point, the best I can say is that the beads are made from at least two different polymers. I'll see what else I can discover after I get back from Tucson.

1_vulcanitebeads.jpg (21.6 KB)  


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Thanks for chemistry report
Re: Thin disk "vulcanite" beads - first chemistry report -- Rosanna Post Reply Edit Forum Where am I?
Posted by: Russ Nobbs Post Reply
01/26/2011, 00:32:31

I'm so jealous of those CSI folks on TV every time I see all the equipment they are supposed to have.

Thanks for testing, let us know what else you learn. I've assumed that the various colors of red have to do with age and fading but perhaps there are several materials involved.



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Re: discs suggestions-
Re: Thanks for chemistry report -- Russ Nobbs Post Reply Edit Forum Where am I?
Posted by: Stefany Post Reply
01/26/2011, 00:57:21

I picture this stuff being made in sheets for some other purpose, and the discs with holes punched out in quantity, perhaps from offcuts.
I've only ever seen them in 2 sizes but never graduated heishi-style as the coconut shell or ostrich/snail/seashell discs are.
would it have been used to protect or insulate electric wiring?
Is/was this polymer stuff a by-product made in Africa from african raw materials?



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I don't think so....
Re: Re: discs suggestions- -- Stefany Post Reply Edit Forum Where am I?
Posted by: Beadman Post Reply
01/26/2011, 06:23:56

Hi Stefany,

I do not find the idea of an African origin very compelling for any plastic beads or artifacts in the early 20th C.

I assume a European origin is much more likely.

My assumption has been that a primary reason these small disks were made was originally for their use as sequins. They were made to be sewn-down, exposing their flat aspect. However, because they are perforated, it was also possible to string them as "beads"—and this happened to become a popular use for them in Africa.

Consider this. The flat surfaces are well-made. In contrast, the edges—which we see when a bead-use is pursued—tend to appear somewhat rough. The disks are mechanically stamped-out, and no work is expended to make the edges nice—as would usually happen in beadmaking. Conversely, why go to the trouble of making nice well-finished flat surfaces, for "beads" that, when strung, would never show this?

Granted, the beads/sequins are made from sheet material, and the formation of these sheets makes the flat surfaces smooth. But the formation of the disks (their stamping) does not suggest an intended bead use.

Just a few thoughts.

Jamey



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vulcanite or vinyl
Re: I don't think so.... -- Beadman Post Reply Edit Forum Where am I?
Posted by: judy Post Reply
01/26/2011, 08:10:28

I have handled, washed and sold hundreds of these beads and these are my thoughts. The true old vulcanite beads only come in black and because of their age are fragile and break easily. The newer brightly colored beads are vinyl. I'm not sure if they are so dirty because they've been used or because they are soiled to appear old. I've been told that Nigerians wear them for ceremonies but I do not know which tribe/tribes. I continue to sell them as vulcanite because that is what people search for when looking for them on the Internet. I have no evidence to verify these thoughts and appreciate your tests and information Rosanna.



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Any pre-1950s examples anywhere of the large black or red ones stitched onto fabric like sequins?
Re: I don't think so.... -- Beadman Post Reply Edit Forum Where am I?
Posted by: Stefany Post Reply
01/26/2011, 09:35:20



Modified by Stefany at Wed, Jan 26, 2011, 09:35:57

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"....a primary reason these small disks were made was...." Operative word: "small."
Re: Any pre-1950s examples anywhere of the large black or red ones stitched onto fabric like sequins? -- Stefany Post Reply Edit Forum Where am I?
Posted by: Beadman Post Reply
01/26/2011, 09:56:30



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Re: Any pre-1950s examples anywhere of the small non-shiny ones used as sequins then?
Re: Any pre-1950s examples anywhere of the large black or red ones stitched onto fabric like sequins? -- Stefany Post Reply Edit Forum Where am I?
Posted by: Stefany Post Reply
01/26/2011, 12:13:39



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Bead precursors may have been gaskets or washers
Re: Re: discs suggestions- -- Stefany Post Reply Edit Forum Where am I?
Posted by: Rosanna Post Reply
01/26/2011, 07:31:34

I have no way to confirm this, but based on some of the industrial uses I can imagine for vulcanized rubber sheet stock, here's what I think happened. The original vulcanized rubber sheet was die cut into gaskets and washers, etc. Someone, maybe in Africa, started stringing small washers and liked the "look". It would have been very easy to start ordering large quantities of "washers", made to a specific size and perforation, and viola, the vulcanite bead business was born. After hard PVC sheet stock was widely available (maybe after WWII, or later?), it would have been much cheaper to make the exact same items from PVC sheet, and they would have been made by the same die-cut parts businesses. I can imagine that boxes of these disks were shipped to Africa, where they were strung by hand into various designs and color combinations.

The Sick catalog shows only black and dark red vulcanite beads. I'm betting that any other color disks we find today are cut from PVC sheet. I'm also betting that I find a few vulcanite disks on the strand, and I think they are going to be the thicker disks - there is a lot of variation. It's a lot easier and cheaper to make very thin PVC sheet than it is to make very thin vulcanized rubber sheet.



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Celluloid
Re: Bead precursors may have been gaskets or washers -- Rosanna Post Reply Edit Forum Where am I?
Posted by: homj Post Reply
01/26/2011, 10:30:28

From about 1900 to 1930 these disks were made from celluloid, a highly flammable material. There were many accidents with these necklaces in African villages when they were worn near fires. We have a reference to confirm this, as soon as we find it we will post it.



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Re: Thin disk "vulcanite" beads - first chemistry report
Re: Thin disk "vulcanite" beads - first chemistry report -- Rosanna Post Reply Edit Forum Where am I?
Posted by: vergret Post Reply
01/26/2011, 13:01:31

There are two kinds of this thin disk, the thinnest are burning with a big flame and the others are rather melting.
Women wear them in Zaire after she was confined ? (got a child)
Best regards,
Greta



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If the smoke smells like rotten eggs then you are burning rubber
Re: Re: Thin disk "vulcanite" beads - first chemistry report -- vergret Post Reply Edit Forum Where am I?
Posted by: Rosanna Post Reply
01/26/2011, 19:29:35

However many plastics have very putrid odors when burning so it's hard to tell just from the fumes. But vulcanized rubber will not melt. Anything that melts and drips when held in a flame is most likely PVC of one sort or another. If fillers like carbon black or other materials were added to the PVC then the material may not catch fire at all, or on the other hand, may burn even more easily than "pure" PVC.



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Re: If the smoke smells like rotten eggs then you are burning rubber
Re: If the smoke smells like rotten eggs then you are burning rubber -- Rosanna Post Reply Edit Forum Where am I?
Posted by: vergret Post Reply
01/27/2011, 12:49:11

I didn't explain it correctly.
The thinner disks are burning with a big dangerous flame, the others are burning slowly. I did it years ago, so I forgot a lot but not how dangerous it was.
I'll burn them again these days.
Best regards
Greta



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In the next couple of weeks,
Re: Thin disk "vulcanite" beads - first chemistry report -- Rosanna Post Reply Edit Forum Where am I?
Posted by: Austin Cooper Post Reply
01/26/2011, 16:20:29

I will do an F.T.I.R. scan to identify the material with certainty and post spectra and results.
Austin



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Do you have similar disks?
Re: In the next couple of weeks, -- Austin Cooper Post Reply Edit Forum Where am I?
Posted by: Rosanna Post Reply
01/26/2011, 19:22:59

Hi Austin, do you have a similar strand that was sold as "vulcanite"?



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Yes, several.
Re: Do you have similar disks? -- Rosanna Post Reply Edit Forum Where am I?
Posted by: Austin Cooper Post Reply
01/27/2011, 02:06:06



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LOVELY to see you!! :)
Re: In the next couple of weeks, -- Austin Cooper Post Reply Edit Forum Where am I?
Posted by: Logan Post Reply
01/27/2011, 09:14:41



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