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V080218-934

Some comments on Health and Safety Issues with Stained Glass and Stained Glass products.


Stained Glass - Safe or not safe?

There are effectively two types of glass available on the market today - The standard ‘annealed’ glass and toughened or ‘safety’ glass. Ok, we can get laminates, self-cleaning glass, photosensitive glass and a myriad of other types, but they all work around the same basic principle. That is, it is either


What's the difference?

All glass is made the same way. Basically take sand (silica), mix it with a variety of other minerals depending on what you are trying to create and heat it in a furnace. The resultant melt is molten glass that can be used to make ‘float glass’ or blown / moulded glass.  The difference is in how the product is cooled.

Initially with window (float) and blown glass it is cooled down at more or less the natural rate. This process is annealing. The glass can then be cut to size and generally worked to create the desired article. For example windows - glass from the factory comes in huge (and I mean really huge) sheets. It is cut down to size to fit a door or window by the factory or glazier. In the ‘old days’ this formed standard window glass. If it was broken (by kicking a football through it), it usually broke into some very nasty shards and splinters.
To get round this problem, a process of toughening (tempering) glass was developed. This takes the worked glass (say a window), reheats it and then cools it a faster rate than normal. The effect of this is to cause the glass sheet to develop stresses within it. These stresses can absorb a fair amount of punishment or miss-treatment of the glass – hence toughened or tempered glass. BUT if you do finally chip the edge or scratch it deeply enough the inherent stresses are released and the glass shatters into small pieces. Do you remember using polarised sunglasses on car windscreens and the pattern that you could see in the glass? That was the stress structure within the glass.

But, and this is the important bit, glass cannot be cut or re-worked after it has been toughened. Stained glass products are made by taking sheets of coloured glass and cutting them to a set design or size and joining them together – usually via lead ‘came’ or solder. Thus we cannot use safety glass. In principle it is possible to cut the glass to the correct size then re-temper it, but the process is time consuming and would be a significant increase in expense on the product.


So how does this affect my plans for a stained glass door window?

Stained glass leaded lights or windows are usually to be found in what is called “vulnerable areas”. That is doors, windows, sidelights and so forth. Building regulations and British Safety standards are clear in saying that stained glass windows or doors are safe and suitable to be used in “vulnerable area’s”, provided (and here’s the rub) the individual panes do not exceed specific sizes. Ours won’t.

The Building Regulations 2000 document, N1, clause 1.2 clearly states:  "Glazing in critical locations should either, a). break safely b). be robust or in small panes.”

It also goes on to say in clause 1.5: “In the context of this approved document a `small pane` may be an isolated pane, or one of a number of panes contained within glazing bars, traditional leaded lights or copper lights."


Heat Loss

The regulations only apply to new doors and window frames, not to old ones being re-glazed. The regulations state that if the area of glass is less than 50% of the door or is a window frame single glazing is sufficient. It is however possible for double-glazing and stained glass to work together and we can discuss this if it is an issue.


LEAD

Stained glass is a traditional craft and utilises traditional equipment and materials - with a little updating for modern technology …

Fundamentally this means that we use lead and lead based solder as a matter of course. It is possible to use other materials (brass or zinc) but this will change the costs of any product. With the sun catchers and sun corners we make we use lead based solder as a standard. Again it is possible to use a lead free solder product but costs will change and this must be specifically ordered.

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