 |
About Us | History | Manufacturing | Types | Cylinder | Period | Letter |
TYPES OF PERIOD WINDOW GLASS: THE CHOICE
There are two main categories of period window glass London Crown Glass can supply and they are designed for different applications.
| Handblown Cylinder Glass | Period Style Glass |
 |
 |
HANDBLOWN CYLINDER GLASS
As a genuine handblown glass, each sheet varies a little from the next. The attraction lies in the small blowing imperfections - a few small bubbles (seeds) or a trace of a ream (fold marks or a wave in the glass) found in this style of glass.
Looking through the glass, the view changes as the eye moves. From outside the reflection gently distorts trees, buildings and the surrounding landscape.
The effect which is entirely authentic is derived from the method of manufacture.
The glass is handblown into an elongated balloon. The ends are cut off to form a cylinder, which is then allowed to cool. The cylinder is split lengthways, reheated and then flattened in an oven.
Cylinder glass marked NR (no ream) is the most suitable for window sashes of the late 17th century up to early twentieth century.
Cylinder glass marked LR (low ream) is generally reserved for 16th century or earlier windows in lower grade housing or stables and for leaded lights. This is because the glass has a more heavily marked surface reflecting an earlier style and a lower grade of glass.
We supply the following Cylinder glasses:
Because Crown glass is
no longer made, we have produced a variant of Cylinder Blown
glass called "Vauxhall Glass". This is similar to
Cylinder Blown Sheet Type NR but during the final process, the
glass is slightly curved to give the bulging appearance of Crown
glass.
PERIOD STYLE GLASS
These glasses are designed to re-create the gently wavy reflection of Crown and Cylinder glass.
From inside the glass appears without the small imperfections found in handblown glass. However because of the appealing reflective qualities, it is used in place of standard window glass.
Ordinary window glass, which sadly is still sometimes specified for period buildings, is usually Float glass or Horticulture Sheet.
Float glass gives a bland mirror-like appearance when glazed in period window sashes. Horticultural Sheet additionally shows a machine wave spreading across the pane of glass, but only in one direction, giving an unattractive effect. Both Float glass (first used in 1959) and Horticultural Sheet (first used in 1919) spoil the appearance of a period building.
Our Period Style glasses are produced by carefully bending mechanically Drawn Sheet (i.e. not handblown) glass in special moulds to recreate the attractive wavy reflection of original Crown or Cylinder glass. Victorian Sheet is also manufactured by a Drawn Sheet process, but is not bent and can be used to make sealed double glazing units.
Period Style glass is generally glazed where no existing original glass remains (e.g. barn conversions) as they do not have the small flaws and imperfections which make cylinder glass so appealing. They appear plain (without reflection) when viewed from inside. However they give an attractive exterior appearance and are a cost effective improvement on the use of modern Float glass or Horticultural Sheet.
We supply the following Period Style glasses:
BUILDING REGULATIONS
We can provide both categories of glass in laminated form to comply with safety regulations for doors and low level windows.