Architectural Glass

Architectural and Restoration Glazing with Cylinder and Crown glass

Glazing has become better and better through the years eventually ending up with float glass or annealed glass. Invented by sir Alistair Pilkington in the 1950s of Pilkingtons Glass. Moulton glass is poured into a tin bath and levels out as it spreads out and levels along the edges. Giving a brilliant flat finish on both sides. As the glass cools and solidifies it leaves the bath in a continuous long thin slab. The glass is then annealed by cooling in a Lehr “oven” and then the finished glass plate finished perfectly parallel.
Sussex sash window restoration has mass stocks of crown and cylinder glass to work on our projects. We make sure that the windows are restored exactly the same as when they were first made.
crown glass installed sussex supplied by sussex sash window restoration ltd

Cylinder and Crown Glass

Float glass is not the same as the glass that was originally in your sash windows. The original glass was called Crown glass and then it changed to cylinder glass which is still made in 3 factories in Europe – Jaslo in Poland, Lamberts in Germany and St Just in France. When the industrial revolution came, depleted forests in Europe changed the way that glass manufacturing was done. From the original charcoal furnaces people had to swap to a more reliable source of heating the raw material and that was to coal and then gas.
Glass used for glazing is made by heating together sand (silica) 70-74% and lime (calcium oxide) 5-12%, at a high temperature with a flux of wood ash or soda 12-16% to reduce the temperature at which the particles fuse.

Why Cylinder glass has different colour tints

The sand was taken from anywhere they could get it including quarries and rivers with not much regard for any contaminates that could have been in the river, this is why old crown and cylinder glass was rarely white or neutral. Sand often contained metal oxides, used in the smelting process. Beachwood ash and soda lime used in the smelting process also gave it a different colour which was mostly green or straw coloured, you will find more crown glass with this sort of tint as it had less tax on it in the mid-18th century this was because it was taxed on the weight of the finished product.

When regular sources of materials came more available in the 19th century and you had more efficient coal furnaces it was more common to have white glass produced. This was more favoured with cylinder because crown glass seemed to diminish due to the fact that it was far inferior a product than cylinder even though it was still made side by side upto the 20th century.

crown glass installed in Corfe
this is an example of old original crown glass in a house from Corfe

How Crown glass was made

Crown glass was the easiest way of glass production with it being dipped in the mouton glass and mouth blown. This was blown into a bubble, cut open and spun on a flat table until it was rectangle shape. Therefore, you would mainly see crown glass in leaded windows because you could only really get 3 small lights for sashes. You could get more out of crown if it was used in leaded lights with less wastage from one sheet.
This procedure created swirls in the glass and bubbles this is one of the reasons that crown ceased to exist any-more. Glass was such an expensive product at the time that nothing was wasted. The excess of the glass that was cut off was called a Bulls Eye and was ground down flat. This was bartered away for produce or ale in many old pubs and buildings that was used for bakeries etc. Especially around the 17th and 18th century.

How Cylinder glass is made

Cylinder glass is also handmade, dipped in the fused molten glass mouth blown into a cylinder bell shape. The person would swing it from side to side to make longer in a pit. Then it was cut off at both ends, then in the middle, and put in a furnace to straighten out. This is what you will see in most stained-glass products because it was easier to mix the products together. Even though cylinder is still distorted in an elongated way, it was a little easier to produce and cheaper.
Even when using Cylinder glass, you have to be very careful of selecting the right type of cylinder glass. This has now evolved into more than 4 different categories from Antique, Russian, Reamy or Seedy Cylinder glasses produced for the crafts or Art market and this makes them poor substitutes for historic window glass.

Crown is still the best and looks perfect in old properties.

Handmade glass brings vibrancy and beauty to your property, the way it disperses the light and gives that warm feel. With a subtle tint that gives it a certain vitality the same as when you look at a mill pond. Because it isn’t flat it catches the light in different angles collecting the full spectrum of colours in the reflection.
If you use modern glass when it all is historic glass it sticks out and looks soulless and just stagnant. In the same way you wouldn’t use modern day bricks in a Victorian or regency house. Crown and Cylinder glass is the only option if you want that authentic antique look in your windows from yesteryear.
One of the best ways to see the difference is to look around many of the Victorian properties that we have in our great cities. look at the reflection of the glass and you will see the difference. You will notice the difference when someone has changed the glass opposite cylinder and crown glass with the plain flat look of a soulless picture.
if you require this glass. We have mass stocks of these products so please do not hesitate to call for a survey. We cover the following areas: Brighton and Hove, Lewes, Hassocks, Haywards Heath, Burgess Hill, Crawley, Gatwick, Uckfield, Seaford, Cuckfield, Eastbourne, Pevensey, Hastings, Shoreham, Horsham, Worthing Pulborough, Chichester, Arundel, East Sussex and West Sussex

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