willong
Well-Known Member
It is entirely ethical to copy a Rembrandt painting. The exercise is beneficial for art students. To offer such copy for sale as an original is fraud. Producing unusual glass colors through irradiation is ethical as well. Most collectors would be happy to add exotically colored examples, such as those illustrated below in a photograph from the article discussed. Many marketers on eBay and other online venues are now offering such wares. Some are ethically disclosing that the colors are derived via irradiation, others are not.
In a comment I posted on 29 April 2021, as a reply to a Dinobottles posting entitled "Digging in the dump of an old farmhouse" in the "Digging and Finding" forum, I again* brought up the subject of glass color changes caused by exposure to sunlight, specifically its UV component. I mentioned the use of Manganese in the production of colorless glass prior to World War One and the substitution of Selenium for that purpose during the war years. My own comment caused me to wonder what elemental substances are employed in modern glass batches to produce colorless glassware.
While conducting online research to answer my self-posed question, I discovered an article entitled "Irradiation Changes Color of Glass" by Mark Chervenka, Editor of Antique & Collectors Reproduction News (ACRN) posted on a website called Real or Repro. The article is one of the best and more detailed discussions of the topic that I have read. It is replete with numerous photos of otherwise genuine antiques which have been significantly altered by irradiation.
In his article, Mr Chervenka considers the practice fraudulent* and cites several instances of high-dollar sales by recognized dealers in the antiques and collectible trades. Some of the buyers were able to prove--the article discusses methods--that the color of their purchase was not produced by the original manufacturer and succeeded in obtaining refunds.
I found the Chervenka article so informative that I decided to post a link to it here for the benefit of other members, both new and old:
www.realorrepro.com
* I have previously discussed the well known (among experienced bottle collectors) color changes caused by solarization. And I have stated my own opinion that modifying the color of antique bottles through artificial irradiation, as contrasted to the natural solarization process accomplished by long duration (years, decades or centuries) exposure to sunlight, is an unethical practice that should, at the very least, be clearly disclosed by sellers of such irradiated items. I personally believe that glass, especially otherwise genuine antique items, artificially irradiated to change its color should be permanently marked to indicate that it has been so altered. A small symbol such as "ICC" (for Irradiated Color Change) could be placed on the base or other inconspicuous area via abrasive, laser or acid etching.
In a comment I posted on 29 April 2021, as a reply to a Dinobottles posting entitled "Digging in the dump of an old farmhouse" in the "Digging and Finding" forum, I again* brought up the subject of glass color changes caused by exposure to sunlight, specifically its UV component. I mentioned the use of Manganese in the production of colorless glass prior to World War One and the substitution of Selenium for that purpose during the war years. My own comment caused me to wonder what elemental substances are employed in modern glass batches to produce colorless glassware.
While conducting online research to answer my self-posed question, I discovered an article entitled "Irradiation Changes Color of Glass" by Mark Chervenka, Editor of Antique & Collectors Reproduction News (ACRN) posted on a website called Real or Repro. The article is one of the best and more detailed discussions of the topic that I have read. It is replete with numerous photos of otherwise genuine antiques which have been significantly altered by irradiation.
In his article, Mr Chervenka considers the practice fraudulent* and cites several instances of high-dollar sales by recognized dealers in the antiques and collectible trades. Some of the buyers were able to prove--the article discusses methods--that the color of their purchase was not produced by the original manufacturer and succeeded in obtaining refunds.
I found the Chervenka article so informative that I decided to post a link to it here for the benefit of other members, both new and old:
Irradiation Changes Color of Glass
www.realorrepro.com
* I have previously discussed the well known (among experienced bottle collectors) color changes caused by solarization. And I have stated my own opinion that modifying the color of antique bottles through artificial irradiation, as contrasted to the natural solarization process accomplished by long duration (years, decades or centuries) exposure to sunlight, is an unethical practice that should, at the very least, be clearly disclosed by sellers of such irradiated items. I personally believe that glass, especially otherwise genuine antique items, artificially irradiated to change its color should be permanently marked to indicate that it has been so altered. A small symbol such as "ICC" (for Irradiated Color Change) could be placed on the base or other inconspicuous area via abrasive, laser or acid etching.
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