we just replaced the last of the old windows in the house...yeah, these aren't them.
i don't know how old the glass was, but the house is over 200 years old and perhaps some of the panes were original to the house.
it is sort of sad to see the windows go. part of me loved the idea of keeping them original to the house.
now replaced, i can admit to having more than a few sideways glances thrown my way when i (casually) mentioned that there must be a way (and reason...i was always looking for a reason) to keep them.
obviously, it is better for the life of the house, and the R-value, to let them go. they weren't anything fancy and admittedly, the house is a lot more comfortable. the colds aren't as cold and the sun isn't as hot.
it can be difficult to see the sunrise through the old panes.
a nor'easter can go a long way to convince you to take the "out with the old" approach
without a doubt, the old "wavy" distorted glass is pretty and full of great character.
i had always been told that the waves showed the age. that the waves are the glass melting, dripping, over the years and settling to the bottom of the frame.
and actually, it seems everybody has a version of this story and that leaves me wondering where it came from and why it is so prevalent.
i suppose it likely comes from the fact that glass is neither a solid or a liquid. because of the arrangement - or lack of arrangement - of its molecules, it is its own state.
somehow the science teachers always leave out "glass" as a state of matter.
and really. it is weird.
i spend a fair amount of time with glass. its intriguing. it requires skill, patience, experience, knowledge, and calm. going into a glass studio any other way guarantees burns and breakage.
honestly, i enjoy the game it plays while you try to wrangle it.
glass toys with you - when it is hot and molten it is like honey. sticky, difficult to control. and heavy. surprisingly heavy.
cool it down slightly (but still way to hot to touch) and it will harden quickly. re-introduce it to heat and you can start again. but although you may have changed its form, it always ends back in its original state.
solid, but not a solid.
cold. immovable. but with so much depth and character.
glass is made up of silica sand (the main material in glass), soda (helps the silicon melt at lower temperatures) and lime (acts as a stabilizer in the finished - rehardened - glass), all in varying percentages. these percentages affect the way the glass is heated, or at least the temperatures it requires to be shaped.
our modern windows have a few other ingredients added. as does lead glass, crystal and items such as glass baking dishes. these ingredients help with everything from clarity to thermal shock.
glass is hard and elastic.
it resists thermal shock, electric current and most industrial chemicals and food acids.
glass is strong, retains heat and it reflects, absorbs, bends and transmits light.
as technology progresses, so does the applications of and the techniques for making glass.
window panes were once made one of two ways:
1. by blowing the glass into a large bubble and spinning it (quickly) into a flat disk, allowing it to harden, and then cutting panes out of the disk;
a window pane from Shelburne, NS - made from the "bull's eyes". these would have been the centre of the disk and considered an off-cut from making panes, but it can also show authenticity of age.
2. by blowing a large large bubble, stretching it into a cylinder (think giant bottle) and slicing down the sides. then gently heating this curve until they "fall" into flat panes. you can watch modern-day glass artists making mouth-blown glass this way on a How It's Made's segment to get an idea of the methods used.
now the process for glass panes is taken on by machines. made in long, wide strips. measured by a laser for even thickness, checked for imperfections, and cut down to ship. the modern windows in our houses can be two or three panes of glass with a spacer, or often gas, in between.
they are solid.
or, well, not a solid
and so, somehow, we think of old glass as melting within its frame.
but the windows aren't melting. the glass isn't flowing down with gravity.
it is true that glass isn't a solid, but its viscosity is so low, that this is not the culprit either.
when you consider how glass sheets were once made you can see that the glass wouldn't have been of even thickness. some sections of the glass were thicker than others and once the panes were cut, a person assembling a window would usually put the thicker parts of the glass to the bottom of the window for stability.
sorry to burst your bubble...
the Corning Museum of Glass (https://www.CMoG.org) has this article with diagrams, to help explain.