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Title: Striking Spheres
Artist: AJGlass
Image created by: AJGlass using an Epson Perfection 1200U scanner and PhotoShop.
Medium: Glass
Type: Soft Glass, 104 Coefficient of Expansion (Moretti/Effetre, Vetrofond, Lausha)
Description: Glass Bead

Details: The dime provided is for scale of the smaller bead image. The smaller bead image is the opposite side of the same bead. Clear glass and transparent Striking Yellow glass (seen in rod form in the top image) were used to create this bead which has been annealed in a kiln. This bead took 30 minutes to make and 18 hours to anneal. No image color correction was necessary.

Discussion: A striking glass is one that will change color when heated (or struck) in the torch flame. The top image is of a rod of transparent Striking Yellow glass. The end of the rod has been exposed to the torch flame and held at the approximate annealing temperature of the glass for a short period of time. The result is that the end of the rod has changed in color from light yellow to intense yellow. Variations in color and intensity can be achieved by varying the temperature of the glass and the length of time the glass is heated.

According to James E. Kerwin, author of More Than You Ever Wanted To Know About Glass Beadmaking, metallic oxides can be dissolved uniformly into molten glass just like sugar dissolves in water. They actually become part of the solution and will not settle out again. When the molten glass is cooled and allowed to solidify, the oxides remain dissolved in the solid glass phase. Each metallic oxide atom will absorb some light of characteristic wavelength and let the rest pass on by. The result is color. The striking affect in glass is caused by changes in the oxidative state of the metallic oxide colorants.*

Further discussion about glass (including types, properties, and chemical makeup) can be found in my scraps by clicking here.

Creation: To create the bone shape, a rod of clear glass was melted onto a bead-release-coated mandrel and formed into a round bead. The round bead was then rolled on a graphite marver to achieve a cylindrical shape. Then the mandrel holding the newly formed cylinder was turned on a 90 degree angle in the torch flame and half of the cylinder was melted and allowed to slowly flow down the mandrel’s length. The now-bone-shaped cylinder end was then allowed to stiffen.

The mandrel holding the cylinder was then turned 180 degrees and the other half of the cylinder was melted and allowed to slowly creep down the mandrel’s length in the opposite direction from the other end. The now completed bone-shaped bead was then allowed to stiffen once more.

Finally, while the bone was still hot, molten transparent Striking Yellow glass spheres were carefully dropped onto it. The spheres were allowed to stiffen in the upper portion of the torch flame where they were kept hot until the Striking Yellow glass turned from light yellow to intense yellow. After the spheres had struck in the torch flame, this bead was immediately put into a kiln to be annealed rather than being allowed to cool in vermiculite. This was done to prevent thermal shock because complex long beads are more prone to cracking than simple smaller ones.

Further comment: Getting some colors of glass to strike can be really difficult for me. Colors such as some oranges and red take me a long time to strike in the flame. Sometimes I can’t get them to strike at all. Luckily, yellow is easy for me to strike and the intense color really makes it worth the extra time and effort.

Legal: Copyright © Aaron J. Greenblatt. All rights reserved. Commercial use prohibited. This image and commentary may not be used for any reason without expressed written consent.

*More Than You Ever Wanted To Know About Glass Beadmaking. James E. Kerwin. 1999. Published by GlassWear Studios, 1197 Sherry Way, Livermore, CA 94550 – An excellent resource on all things concerning glass beadmaking.

Please click here for more images of my glass work.

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