Glassware Decoration Limits

In the July Issue of Orton Firing Line, there was a reprint of Peter Cassebeer's article on the decorating industries voluntary standard concerning enameling, with lead and cadmium enamels, on glassware. Cassebeer states that decoration area limits sometimes don't satisfy the standards.

The voluntary standard for the decorating industry for lip and rim limits is based on the ASTM test C-927-80, which provides a test method for lead and cadmium extracted from the lip and rim area of glass tumblers externally decorated with ceramic glass enamels.  Within the test procedure, a 2 centimeter distance from the tumbler rim is established as the limit for the lip contact area.  The decorating industry has chosen to not decorate above this 2 centimeter mark with lead and cadmium based glass enamels to minimize the potential for consumer exposure to heavy metals. 

However, Cassebeer noted that some decorators are using a 3/4 inch decorating limit for tumblers, meaning that they decorate the exterior surface of a tumbler up to, but not above, 3/4 of an inch from the tip rim of a tumbler.  Consequently, there is almost one millimeter difference between these measurement. 

               2 centimeters = 20 millimeters = 0.787 inches

               3/4 inches = 0.750 inches = 19.05 millimeters

This tiny discrepancy could make the difference between complying with the decorating industry's voluntary lip and rim standard or not, or selling glassware that meets FDA criteria for a safe product and one which fails.  The difference translates to a 5% surface area discrepancy, and also potentially exposes the tumbler to 5% more decorated surface area to be leached from in the ASTM C-927-80 test.  If the tumbler was close to the FDA limits for lead and cadmium in the lip and rim area when using 2 centimeters, this extra 5% exposure may be enough to push it over the limits.  Glassware decorators are encouraged to use the 3/4 inch measurement as their decorating limit. 

This scenario shows how accurate and careful artists and craftspeople must be with their measurements for health, safety, legal, and artistic reasons. 

Art Hazard News, Volume 18, No. 4, 1995

This article was originally printed for Art Hazard News, © copyright Center for Safety in the Arts 1995. It appears on CAR courtesy of the Health in the Arts Program, University of Illinois at Chicago, who have curated a collection of these articles from their archive which are still relevant to artists today.