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Visual Concerns
Bubbles are nearly impossible to avoid. Obviously there are numerous
variants to this rule, but assuming a proficient and conscientious
gaffer the bubbles you may see are generally caused by the
manufacturer of the color not the glass artist.
Here's how it works. One of the manufacturers of glass color creates
a huge crucible of a certain color. The appearance of this color is
always dark black and it is opaque to light. Their color gaffers
create the color bar by gathering layer upon layer of the black
substance, rolling it on the marver in-between gathers. Invariably,
small bubbles are created in-between the layers. These are the
bubbles you see in the finished product. It is impossible to see
these bubbles until the color is stretched thin enough to let light
through, unfortunately this is the point that the piece is nearly
finished. So, we live with these small bubbles.
Lip and Edge Control
The lip of the piece is another easy indicator of the skill the
artist has mastered. When "necking" a piece to prepare for
the punty the artist will use "jacks" to constrict and to
chill what will ultimately be the lip of the piece. This contact with
the special steel leaves a mark logically called a jack mark. This
mark should not exist. The glass should be clear and smooth. Another
poor quality technique is to cover the jack marks with a "lip
wrap". It's kind of like hiding a ½" gap in the
flooring with carpet, you'll probably get away with it, probably.
Chill marks on the lip should not exist. They look like surface
cracks with smooth edges.
Punty Issues
The punty is the device that allows the artist to change ends. It is
quite acceptable to leave the "punty mark" on the bottom of
the piece as long as it is not exposed. The punty mark is one of the
signs of a blown glass object as opposed to a cast object. There
should be no sharp edges and the piece should sit flat against the
table without any rocking. Some artists polish the bottom of the
piece, but this is mostly personal choice unless it can be seen by
looking through the bottom of the glass.
Body of the Piece
The body should be free of paper burns, chill marks and cords. Paper
burns are small bits of ash that stuck to the glass when cooling and
shaping. They look like dull spots in the layers. Chill marks are
uneven waves of glass; they refract light differently than the
surrounding area. And finally cords are waves of glass that look like
strands of material that refract differently than the surrounding glass.
Obviously there should be no folds, cracks, holes, nicks, scratches,
or any other visually distracting artifact. Note, some artists may
purposefully use some of the above "problems" use your discretion.
Color - Generally the color should be consistent
throughout the piece. Many exceptions to this rule exist however, so
again use your discretion. As an aside, the deeper the color or
the more color used greatly increases the difficulty of the piece.
One technical issue is that different colors will absorb heat at
different rates hence they will also dissipate heat at different
rates. An even bigger problem exists when different colors which
react at different rates are combined. For instance, enamel white is
very stiff and when combined with some diffuse colors this white will
act as if you were combining concrete with molasses . . . not a great
fit. The same happens with heat, this same enamel white will deflect
heat (keeping it cooler and hence more stiff) and when combined with
a green that readily accepts heat compounds the disparity that
existed due to the physical property of the color.
— Reprinted with permission from Glass Act,
artist, Ross Neder |