Paul Coleman, Project Manager, talks us through another dimension added to the Folly – glass and windows. Why?
Glass possesses the quality of bringing life to a building, adding atmosphere and ambience – glass is seen both internally and externally and at the Folly gives some truly amazing reflective qualities. Outside it is more dramatic where we see changes in the pattern of the glass, the refracted images caused by the irregular glass finish which handmade glass possesses, a soft wave and shimmer or ripple and a different texture to the building being offered. The poetic stuff out of the way, lets talk fact….
The Folly was originally glazed but over the years windows were broken or vandalised and eventually in the 1980’s all openings were boarded up (unfortunately people in the past loved to throw stones at the old girl !!).
The windows were predominantly metal framed inserted into the gothic stone arches and glazed with leaded light windows – we see evidence of this on the early photos (which have been again our source of information to replicate the window style and design),
We also had one surviving metal frame which we found removed from the stonework and buried under the piles of pigeon guano and another mangled piece broken and twisted.
All of this again has led to us being able to piece together information to enable us to replicate the metal windows which are back in the building – traditional ironworker crafts and the team at Cliveden have helped replicate the windows.
But the glass, we had a lucky find (well lots of little finds) – we had to excavate around the perimeter of the tower to reduce the ground level (as too high) a resulting 220 tonne pile of soil was heaped up. And from this pile we started to see fragments of glass, leadwork for the windows and other interesting pots and pieces. We excavated carefully to retrieve more, and this gave the final clues for the building – giving the glass type, thickness, pattern, size, colour and critically the lead work size to hold the glass in place.
We found lots of different glass dating over a number of years which shows it had been repaired and replaced in many areas (caused by accidental breakage or unfortunately vandalism). Our glass expert looked at the varying samples and concluded :
The glass could be split up into three main groups:
- The thin pieces with iridescence are crown glass ( C18-19th), very early glass in deed,
- Most of the rest of the thinner glass is sheet glass (C19th-early 20th), this was probably cylinder glass or bed glass,
- The thicker pieces of glass are float glass post 1959 – this is very flat as you would see in a modern house,
Thicknesses range from 1.2mm crown, to 3.5mm float glass (modern glass) and colour varies from iridescent, clear polished, pink manganese tint, greenish iridescence, green tint and blue tint.
So, we knew we have leaded light windows, Small square bits of glass held together with sections of leadwork which form a larger panel which fits into the metal frame of the window. Some of the windows are opening (hinged) and some are fixed – we see this on the old photo’s.
The lead work called Lead Cames – is an ‘H’ profile, where the glass slots into the legs and holds it into place,
Looking for new glass…
It’s a challenge trying to match glass, as there are so many things to think about, mainly from my perspective it about the thickness, colour and texture. Texture is important as when the glass is made in a traditional way, it has irregularities in it (the ripples, air bubbles, ridges) these all give life to the glass and when you look at an old building or through an old window, you get that distortion in the view which looks wonderful. Plus the light falling on or through it bends and reflects giving some weird and great patterns.
So we choose a modern glass produced to give traditional appearance and very thin (2-3mm thick), but one which had that movement in the glass and as seen, does give a truly wonderful appearance to the building.
To describe the type of glass we found,
Crown Glass –made by blowing and spinning a huge blob of glass which gradually enlarges to make a huge flat spinning disc. Several panes of crown glass could be cut from one disc, the closer to the middle is where the thicker bits are and towards the edges it gets thinner. The outer edges were prized, and would have been very expensive. The patterns in the glass are obviously circular,
Cylinder Glass – made by blowing a very large bottle shaped cylinder, the ends are cut off and then the tube is cut along its length. Its then heated and unrolled to give a flat piece of glass. It has a good pattern of ridges.
Bed or slab glass – made by flowing molten glass into a big flat caste, once hardened it would have been polished and ground flat,
Float glass – modern glass which is plain and has no texture to it, the molten glass is floated over liquid tin to give a very uniform thickness and ‘clean’ glass, it is then repolished and ground flat,
So, its not just glass – it’s a work of art….