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Glazing

 
 

When I spoke to a representative from Marvin, I was told that they would even install Restoration Glass. (Restoration Glass is new glass made with slight distortions which create that extra sparkle glass had years ago. (800)221-7379 )

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The retention and repair of original windows is strongly recommended by the various conservation bodies, such as English Heritage and the Society for the Protection of Ancient Buildings (see also “Sash Windows” Leaflet). The importance of the original glass to the fabric of a house cannot be too highly stressed. The varied colours and reflections from the surface of old glass give a texture and depth to the appearance of an old window and the refraction of sunlight passing through the glass produces a distinctive pattern where it falls. Wherever found it should be retained as a historic feature.

"Glass and Glazing, A Guide to Historic Glass," Building and Maintenance Guide, Planning Department of the London Borough of Islington.

 
 

Repair, breakage

The inherent qualities of hand-made glass contribute much to the liveliness and character of historic buildings. As crown glass is so thin and delicate, extreme care should be taken to avoid damage during building operations. Ideally, cracked panes should be left in situ, unless too badly damaged to save, or where the panes have to be removed in order to repair the glazing bars. If old putty cannot be removed by hand, a solvent paint stripper or soldering iron may be used to soften it. Several applications may be required.

Original glass provides the best replacement for broken panes, and where a window has decayed beyond repair, its old glass should always be set aside for re-use. Second to this isnew glass which, with care, may be found to closely match the original material, but avoid material which is too reamy or over-distorted. New cylinder glass can still be obtained, but commercial production of crown glass ceased recently and this type may be unobtainable.

Regular commercially available new glass is unlikely to provide a suitable match. Greenhouse glass and some Eastern European glass can be suitable although supplies of the latter are variable in supply and quality, and a few specialist suppliers offer modern substitutes for old glass, mostly in imitation of cylinder glass (since the character of the hand-blown and spun crown glass is impossible to duplicate by any other process).

Wrightson, David. The Conservation and Renewal of Timber Windows, Public Information Leaflet, Cathedral Communications, Wiltshire, England [PDF file]

Even though double glazing in a weatherstripped frame can roughly halve the heat loss through window openings, installation costs are so high that savings on fuel bills are unlikely to cover this outlay for at least 60 years.

Wrightson, David. The Conservation and Renewal of Timber Windows, Public Information Leaflet, Cathedral Communications, Wiltshire, England [PDF file]

 

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