Iridescent Satin Glass Vase, 1920s

• Pontil Mark - A pontil mark, also known as a pontil scar, is a distinctive mark or scar found on the base of certain types of glass. It is a remnant of the glassblowing process and is particularly associated with handcrafted items made prior to the widespread use of automated manufacturing.
  
  The pontil mark is created during the final stages of production. After the glassblower has shaped and formed the glass object, it is removed from the blowing iron. At this point, the glass object is often attached to a solid rod called a pontil rod or punty for further shaping, finishing, or attaching additional components. The attachment point is typically at the base of the object.
  
  Once the glass item is complete, it is detached from the pontil rod, leaving behind a mark or scar on the base. This mark can take various forms, such as a rough or irregular surface, a concave or slightly recessed area, or a small circular scar. The presence of a pontil mark indicates that the item was handcrafted rather than mass-produced.
  
  Collectors and historians often use pontil marks as clues to determine the age, authenticity, and production methods of glass or ceramic pieces. Different types of pontil marks may suggest different techniques used in the production process. For example, an open pontil mark is one where the scar is left as an exposed, roughened area, while a closed pontil mark occurs when the scar is smoothed or covered in some way. It's important to note that not all handcrafted glass items have pontil marks, as some artisans developed alternative methods for finishing their work. In Edwardian times the pontil mark was oftern ground off leaving a concave circle in the centre of the base of the object.
  
  The use of pontil marks diminished with the advent of industrialization and automated manufacturing processes in the 19th and 20th centuries.
  
  

• Irridescent Glass - Iridescent glass has a shimmering or rainbow-like appearance due to the way it reflects light. It is created by applying a thin layer of metal oxides to the surface of the glass while it is still hot and malleable, which then creates an interference effect that produces a range of colours as the light reflects off the surface. The exact colours and patterns created by iridescent glass depend on the specific types of metal oxides used and the techniques used to apply them.
  
  Iridescent glass was first developed in the late 19th century, and quickly became popular for use in decorative art glass and stained glass windows. Some of the most famous examples of iridescent glass were created by artists such as Louis Comfort Tiffany and his studio, who used it extensively in their distinctive lamps, vases, and other decorative objects.
  
  

This item has been included into following indexes:

• WMF (Wurttembergische Metallwarenfabrik) - glass makers 37