Wednesday, 11 March 2015

Lampworker's vocabulary: glass (P.2)

I've already told you a little bit about glass in general, however it was only a beginning of stories about lampworking and glass, and today I'd like to tell you about types of glass rods, while my next post will be dedicated to different glass manufacturers.

Generally speaking, lampworkers use few types of soft glass, each of which has proper characteristics: transparent, alabaster, opaline, filigree, pastel and special, aventurine and so called odd lots - these are mostly pre-colored glass and this is how glass usually classified by Effetre (Moretti) and Vetrofond, two oldest glass manufacturers. There are also glass that contains silver. Most lampworkers use rods of glass 7–8 mm in diameter, however there are thicker rods also available, as well as stringers that are usually 1-3 mm in diameter or even thinner.

Transparent glass is presented in wide assortment of colors - from crystal clear to very dark purple. Some of such rods can seem to be uncolored and reveal their color after heating only - like the orange one on the photo below. Transparent glass is relatively harder to melt, slightly changes its color in the flame before becoming red and melting, and usually creates solid color. It can contain air bells if the glass mass was originally padded badly while manufacturing, or if lampworker - either for purpose or not - allowed them to be created during the work.

Pastel and special glass present non-transparent type of glass. 'Special glass' usually means the assortment of yellow, orange, red and brown colors, while 'pastel' - all others. Such rods are melted easier than transparent, sometimes change their color significantly in the flame (for example, yellow become red even with a light heating) and can create free designs of color while applied to the bead or other object (you can notice them slightly noticeable here, for example, if you take a closer look).

Alabaster glass quite similar in characteristics to the non-transparent glass, however does not have wide range of colors and has heterogeneous structure: there are conspicuous air bells in it. It allows to create pleasant, slightly transparent beads and other objects. Other glass if applied to the alabaster base in most cases will create patterns with quite smooth, a little bit uncertain edges.

Opaline glass is the most poor in sense of colors, however all rods of this type are a little bit transparent (sometimes it seems like they are glowing with a color from inside), have pleasant pastel colors and homogeneous structure. Opaline glass is very similar to alabaster in sense of working with it, and unlike pastel and special glass tends to create solid color, though some colors can be revealed after heating only. This type of glass sometimes demands quite gentle attitude: for example, yellow can change its color to dark brown if heated for a long time.

Filigree glass presents a palette of different colored glass encased into transparent. It is possibly to create such stringers and effect without using these rods, however in some cases filigree glass can be very useful.

As for me, the most interesting are the odd lots (or, sometimes, 'cool colors') - relatively rare glass rods, that in some cases are made once and never manufactured again, of unusual colors or that combine transparent and non-transparent glass or contain few different tones in one rod. Almost all manufacturers make them on frequent basis or from time to time, and they are always quite expensive, however worth their price.

Main feature of the glass that contains silver is that in rods it looks completely different from the glass you'll see in the bead at the end of the process, and it can create quite different colors and designs even if worked with during one day. This type of glass reveals its color during the processes of reduction, reaction and overheating, and sometimes after annealing only. It's quite expensive, but allows to create really fantastic effects!

So called aventurine is the glass that contains suspended oxidized metallic particles and therefore imitates aventurine quarts, a gemstone. It is available in gold, dark blue and green color, and sold in different forms: rods (inc. filigree), stringers, frits and chunks of different fractions. Aventurine glass was first made in Venice in XV century to imitate gold and since then is widely used for decorating.

There are also dichroic glass, glass with different inclusions like pearlescent pigments, etc.

To take a look at, purchase and order items made of the glass described above in the lampwork technique, please, visit my Etsy store.