| The main faults associated with crystal are bubbles or “seed” which form during the melt process and are refined out as the crystal cools after the melt. In practice not all the trapped gases escape leaving some in the glass. Larger bubbles or blisters can also be formed when the crystal is gathered, particularly if the team is working very fast on a piecework system. At Cumbria Crystal we work slowly to minimise the faults in the crystal and ensure that all possible care is taken during manufacture. Small bubbles or seed will be present in a proportion of any batch of hand made glasses and help each piece be unique. However these bubbles should not be readily apparent and should not appear at the top or rim of the glass.
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| The other faults in crystal are associated with the interface between the molten crystal and the clay pot in which it is melted. Particles of silica can detach from the pot and are known as stone, appearing as small white inclusions in the glass. Elements of the pot can also dissolve into the
crystal forming a glass, which differs in chemical composition from the main body of the crystal. If this is gathered into a piece it appears as fine lines due to its different composition giving
different refractive properties and this is known as cord. |
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| Cumbria Crystal uses the process of inside sintering to keep faults to a minimum. Prior to use the clay pot that holds the crystal is fired on the inside at 1500 C, which makes the clay very hard and reduces its porosity thereby making it highly resistant to corrosion and degradation. |
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| The moulds used for glassblowing are coated with a lining and if this wears unevenly as blowing proceeds this can cause mould marks which appear as ripples or lines on the surface of the glass.We continue to free-blow our large pieces because a mould does not touch the surface and the finish is better. |
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| Cumbria Crystal is dedicated to the production of full lead crystal in England using only traditional handmade methods. Our size and stringent quality standards ensure exclusive products for
prestigious clients and our in-house skills enable us to offer an unrivalled bespoke service for luxury crystal. |
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