What is the difference between 'cut glass' and 'pressed glass'?
Most people understand the difference between 'hand-blown glass' and 'molded glass' as hand-blown glass is shaped and molded while it is molten red-hot using special tools and techniques. Molded glass is poured into a mold while still molten and allowed to cool into the shape of the container.
Hand-blowing results in glass with a smooth finish on the surface. Then another technique known as 'cold-working' is performed using various shapes of motorized stone wheels to 'cut' patterns into the glass, and wood polishing wheels to bring back the smooth luster. The procedure is lengthy and delicate, but produces the crisp, sharp detail for intricate patterns.
Molded glass has patterns cut directly into the containers used for the molten glass. The hot glass is forced or 'pressed' into the molds . Once cooled, the individual pieces are removed, and then also polished. This procedure is used for mass-producing larger quantities, and may not have the same detail as cut glass.
How does 'lead crystal' differ from glass?
In addition to the very specific high-grade silica (sand) used by various manufacturers, lead is also added as a 'softening' ingredient which allows fine, sharp edges to be cut in patterns, and smooth surfaces to be polished to a high gloss. One characteristic of fine lead crystal is its ability to 'refract' light; diffusing it into the 'colors of the rainbow.' Another is the pleasant tone it emits when lightly tapped, or in the case of stemware, the 'ringing' created by rubbing a damp finger around the lip of the container.
What is hand-polished crystal? Acid-polished crystal?
Hand-polishing is the lengthy process of holding lead crystal against a rotating wood wheel until the surface is uniformly smooth and highly glossy. Acid polishing is a process used in mass crystal production which attempts to achieve the same smooth, glossy results by washing rough glass or crystal surfaces with an acid solution.
The process of 'restoration' attempts to reverse the ravages of time and use to bring an article back to the state it was in when 'brand new.' In the case of lighting fixtures, that may include refinishing, re-plating, rewiring, and replacement of components.