A Lesson in Toxic Issues
A LESSON IN TOXICITY ISSUES
This was written by Dave (the Bug Doc) Shetlar in early Feb. 2005 to those interested members and readers of the www.cga mailing list: It makes some very good detail points.
揋uess I have to get in here and try to head off another of the alarms that periodically get set off concerning the toxicity of making carnival glass (and stretch glass)! While it is definitely true that many of the chemicals used in making glass can be toxic, and the fumes created by spraying hot glass with metallic salts, usually held in solution by dilute hydrochloric or sulfuric acid, the real issue is exposure. As any toxicologist would say, 搕he dose makes the poison!?In short, at sufficient levels, even oxygen di-hydride can be toxic if you take enough of it in a short period of time! (There was a recent spoof by a grade school student in his science project where he asked people if they would be alarmed if they were exposed to this 揹angerous?chemical. 80% of those asked said, 揧ES!?
Arsenicals are not normally a large part of a glass batch nor involved with the iridizing process (unless you wanted a white, powdery coating!) If you look at the recipe that remains from E. A. Dugan's notebook (page 26 of the Dugan/Diamond book by Heacock, Measell & Wiggins), for a turquoise blue opal glass, you have 300 parts sand (silica), 81 parts soda (calcium carbonate), 50 parts lead (most likely lead oxide), 24 parts pearls (potassium phosphate), 54 parts feldspar (most likely potassium aluminum silicate), 50 parts fluorspar (calcium fluoride), 5 parts kryolite (sodium fluoraluminate),-actually used as a stomach insecticide as the crystals punch holes in insect gut cells!), 5 parts arsenic, and 7 oz. of copper scales (for the blue color). As you can tell from this formula, there's a lot more lead and fluoride than arsenic in the batch and the dust during the mixing of the batch would be quite dangerous. However, once fused in the melting process, none of these chemicals would be chemically active. If they were, all of our lead crystal glass would be highly dangerous to use! (That rumor goes around occasionally).
I hear all the time that cobalt (blue), selenium (pink to red) and uranium (yellow) compounds that are used as colorants in glass are highly toxic or are no longer available. While certain compounds containing these elements can be quite toxic, the forms that end up fused within the matrix of glass are not. I remember having to bust out laughing about two years ago when someone was trying to sell a cobalt blue pitcher set on eBay with the statement that it was no longer legal to purchase cobalt, so these were the last of the dark blue pieces to be found! What a hoot!
If you go to any glass manufacturing facility today, they well know that the batch mixing is the area that one is most likely to be exposed, mainly through inhalation of the ingredients, some of which can be pretty toxic. Batch mixers are well-suited and masked to reduce their exposure.
Doping (spraying the metallic salts onto hot glass) is a very different issue. Iron chloride and tin chloride when put into 搈ild?acids can produce some pretty toxic fumes when they hit hot glass. In early factories, if the dope was sprayed without the use of a fume hood (as is done today), the doper and handlers may have been exposed to some pretty dangerous fumes. However, I suspect that it was really not much worse than what was happening in the iron smelting, and steel manufacturing factories of the same period!
In my recent talks with Frank Fenton, he kept stating that they could not produce the marigold color because of OSHA regulations. I notice that they have recently produced a compote with a marigold finish, so they must have found a way to get the iron salt onto the hot glass without producing fumes that trigger OSHA concerns.?/FONT>
Re: Doping of carnival glass.
In discussing the risk and danger of exposure to the metallic sprays with the last remaining Hansen brother, living in Northern California during the `80s, he confirmed that his two brothers had departed this life with serious lung/respiratory complications, resulting in improper protection against inhalation/ingestion of the chemicals.
Although this surviving brother knew the formulas used for the Hansen mixtures, he would not relate them to a nephew, for fear of his neglect in application of the spray. Therefore, in his spare time, the nephew was relegated to the art of blowing small animals, figures, etc. in various colors to supply the glass outlet on their property. An airline pilot, the nephew had other means of employment.
Dean & Diane Fry - 5/05
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A Few Words on Vaseline Glass · A Lesson in Toxic Issues · A Personal Reflection into Fenton Past · America the Beautiful · Beginners Journey · Brocaded Roses by Central Glass · Don Grizzle and His NW Jardiniere · Famous Last Words · Fenton Dragon & Lotus · Fishscale & Beads · Frank M. Fenton · Grapevine Lattice · In Memory Of George Loescher · Lattice & Points/Vining Twigs · My First True Love ~aka~ Cosmos & Cane · My First Days of Carnival Glass Collecting · Popularity VS. Actual Rarity · The Different Millersburg Peacock Molds · The Myths and Mysteries of Straw Marks · The Stuff We Prize is Just on Loan · Thoughts From Fay · What A Message · Wholesale vs. Retail
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