Tuesday, 3 March 2009

Lead Came

Lead came is often just called came. There are two basic types of lead: hard lead and soft lead.

Soft lead is 100% pure lead with nothing added. Soft lead strips need to be straightened in order to remove the propensity to stretch and sag. The advantage of soft lead is being easier to bend and shape to curves and that straightening removes any kinks in the length. Within 50 years it will need to be replaced.

Hard lead has antimony added which stiffens the lead. This results in a stronger finished panel. However this kind of lead deteriorates relatively rapidly. The advantage of hard lead is the added strength and not having to stretch it. It will need to be straightened just before use though. It is still malleable enough to conform to most curves.

Came is available in many shapes, although H, U and C are the most common. The lengths are usually about 2 meters (6 feet). C and U shaped lead is used on the outside of a panel. H shaped lead can be used on both the interior and edge of a panel.

The came’s top and bottom are the flanges and the width of the flange is the nominal size of the lead. These flanges can be flat (parallel surfaces) or rounded (a slight dome on each of the flanges). The central part of the came is called the heart, normally 1.2mm (1/16”) thick.