Oriel Glass Studio

Glass Facts

If you are considering commissioning a stained glass window it may be helpful to understand some of the terminology and techniques used as these will affect both the character and cost of the finished work.

Terminology
  • Machine rolled glass  This can be clear or coloured glass often rolled with a variety of textures and useful to afford privacy in a front door, bathroom window or similar.  Because it is machine made is is relatively inexpensive and consistent although sometimes rather bland in quality.
  • Antique Glass  You may consider this as glass made in the old fashioned way, mouthblown and consequently less uniform.  Antique glass often contains tiny bubbles (seedy) and or rippling lines (reamy)  making it much more delicate and delightful to the eye.  It will still vary in quality with the very best, and consequently most expensive, blown in England, full of irregularities and character.
  • Pot Metal Glass  This glass is single coloured all the way through, molten glass ''gathered'' straight from the ''pot'' then blown to form a sheet.
  • Flashed Glass  The first gather of glass is taken from the ''pot'' then dipped into a second colour, the resulting sheet thus having one colour in the body covered with a thin veneer or ''flash'' of the second colour.  Because the flash can vary in thickness across the sheet it may impart a wonderful variation in hue.  Acid etching or sandblasting can then be used to erode away the flash enabling all manner of figurative or decorative effects.
  • Streaky Glass   This is a flashed glass where, through the skill of the glass blower, a second, even third or fourth colour may be spread in swathes across the sheet - the Rolls Royce in antique glass!  Cheaper machine made alternatives are available which can be very pleasing in domestic windows.
  • Opalescent Glass  This is glass given a milky consistency largely developed in the United States following in the footsteps of  Louis Comfort Tiffany and John La Farge.  It may be uniformly opalescent similar to a ceramic or infused in streams described as ''whispy''.  High quality american imports come in a spectacular array of colour combinations and textures, primarily intended for lamp work but used judiciously, creating interesting effects when combined with more traditional stained glass. 

Techniques
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  • Leaded lights  Glass, often coloured which is cut to a pattern then simply leaded together.
  • Stained Glass  Although used as an umbrella term for many forms of coloured glass, strictly ''stained glass'' is again coloured glass cut to a pattern but this time, worked with a variety of techniques; etching, paint, stain and enamels.
  • Glass Painting  Not to be confused with cold acrylic paints used on decorative wares, this is vitreous paint fired onto the glass and thus rendered permanent.  Normally in shades of black or brown, it can be used for linework or ''tracing'' of figurative detail, as a wash or ''matt'' for areas of light and shade or more freely to give a host of decorative and textural effects.
  • Enamelling  Similar to the painting of ceramics, coloured enamels can be mixed and fired onto the surface of the glass.  Very popular in the eighteenth century it still has interesting contemporary possibilities although perhaps without the intensity achieved with coloured glass.
  • Silver Stain  Invented in the early fourteenth century, oxide or chloride of silver was found to stain glass in various shades of yellow, from a pale lemon through rich amber to a reddish brown.  Relying on the chemistry of the glass it is notoriously fickle but can give glorious effects when used with skill or by happy accident!
  • Acid Etching & Sandblasting  As already described these techniques can be used to erode a ''flash'' from the surface of glass.  Used traditionally, for example in  heraldry, figurative detail may be drawn within a single piece of glass, a golden lion on a red ground or, used more freely may impart a fabulous variety of texture and hue.  Acid/sandblasting may also be used in different ways to give a degree of opalescence, often patterned to the surface of translucent glass.
  • Fusing  Different colours of glass may be heated to a semi-molten state and fused together to give interesting contemporary effects.  Because all glass expands and contracts as it warms or cools, the rate of that movement depending upon it's chemical mix, it is essential that any glasses fused together are tested to ensure that they are compatible.  Only in this way will they stand the test of time without cracking.
  • Slumping  Again glass is heated to a semi-molten state, this time over a mold which allows it to fall  or ''slump'' thus picking up shape and texture.  Used as a component of stained glass, this technique can enrich a window allowing light to play in facets and patterns on the surface.