Like many natural materials, lead is subject to an atmospheric transformation when exposed to the environment. This process, called Oxidisation, is entirely natural and eventually causes the lead to adopt a weathered ‘ appearance like that found in traditional stained glass windows.
Why does oxidisation occur?
When lead is exposed to environmental factors, particularly rain or snow, compounds within the metal react to form a natural, non porous surface coating.This protects the lead by preventing any further reactions with the atmospheric conditions. It is this natural protective barrier, called a patina , that gives the traditional look.
Factors affecting oxidisation
There is no way to tell how quickly oxidisation will occur. The main influencing factors include time of year, weather conditions, location ,environment and airborne contaminants.
The process of oxidisation
Several temporary effects are visible during oxidisation and are most noticeable in the initial stages. The lead can take on the appearance of several different colours, often looking bronze, blue, gold and green, creating a similar effect to that of oil on a wet road. This is a natural part of the process and the colours will gradually fade.
Another common part of the oxidisation process is the appearance of discoloration, spotting and white powdery deposits. This occurs when the lead fi rst comes into contact with water. Like the colour changes this part of the process is natural and temporary.
However, as the white powder can often run during wet weather
it is sensible to wipe it off occasionally to stop it staining the glass or the window frames.
Treating the lead
There is no need to treat the lead as the process will occur naturally. However, Patination Oil can be applied to prevent any discolouration or blemishes in the early stages. Additionally, this controls the process by encouraging the patina to form more quickly. When using Patination Oil it is important to apply it as soon as the lead profile is installed, as once the natural process starts,and any blemishes appear, it will be too late to use it.
For more information and to see our Patination Oil product range, please see pageA14b.
Colour options available can be split into 3 categories: Natural Lead has no coating and will oxidise over time to give the’ weathered look’ of traditional old leaded windows.To improve the performance of natural lead, we recommend using patination oil It is possible to solder natural profiles Coated Leads use advanced pigmented polymers to create the extra colour option sin Brass, Satin Brass.Antique, Satin Antique, Ebony and Platinum. These coatings also provide additional weather resistance and retain their appearance for many years.
PolyesterPowder Coating gives the White, Gold, Chrome, Titanium,Antique Iron end Antique Copper their colour end these finishes are recommended for interior applications only as they offer limited weather resistance.
Health and Safety
It is recommended that you follow health and safety precautions when working with and handling lead.
The Lead Health and Safety data sheet, published by the Health and Safety Executive can be downloaded from: www.hse.gov.uk see publication free leaflets/lead.
For California residents title 22,
article 6 (proposition 65] on Clear and Reasonable