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Lead Aging Process
All lead products are susceptible to a weathering process known as oxidation. This is a natural process that forms a patina which effectively protects the lead from the elements.

The patina is made up of a layer of insoluble lead salts that give the appearance of traditional grey lead. Look at an old church window, or an old leaded light and you'll see the effect of the oxidation. The patina is made up of normal lead sulphite, normal lead sulphate, and normal lead carbonate.

During the initial stages of oxidation the lead can display many and varied colours. The colours that you will see are partly determined by the angle of view but can include white, copper or green a blotchy appearance or even powdery deposits. This happens as the lead comes into contact with moisture and is basic lead carbonate. Householders should be aware that the appearance will settle down and that any action to remove the patina will result in the process starting over again.

The effects of oxidation will be different in different areas, but it will settle down to form the traditional patina in time. There is, however, no way of saying how long this will take.

This basic lead carbonate can run off onto the glass under some circumstances and should be cleaned to avoid the likelihood of any staining.

How much of a problem this oxidation becomes is governed by environmental factors, but in the longer term, the patina will form and the traditional colour will become evident.

Controlling Oxidation

Use pre-aged antique lead.
Use powder coated pewter lead.
Control with patination oil, (oxidation will still be evident).
Should patination oil be used, the panel should not subsequently be cleaned with solvent based or abrasive cleaners.
Patination oil overcomes the problems of discolouration and basic lead carbonate release which occurs during the initial stages of oxidation. This is what causes early unsightliness.

119-125 Bridge Road, Leicester LE5 3QP T: 0800 1694357 F: 0116 2460462 E: enquiries@leicesterglass.co.uk