Q & A: Is machine cast lead more prone to discolouration than rolled?

QUESTION:

As with last month’s ‘Ask Midland Lead’ column, which queried machine cast lead’s chemical composition, this month’s newsletter reader question was also mirrored in our recent industry research findings: “Is machine cast lead more prone to discolouration than rolled?”

ANSWER:

The survey, which collated the views of over 250 lead merchants and end users, found that while for many no distinction is made between machine cast and rolled lead, where distinction was noted, the idea that machine cast lead is prone to discolouration, while rolled remains shiny, was prevalent.

Being the only supplier of both machine cast and rolled lead sheet in the UK, we’re continuing on our mission to educate the construction industry when it comes to misconceptions such as this one.

The fact is, all lead sheet begins its life shiny. However, being a naturally sourced material once exposed to the elements lead – whether machine cast or rolled – can get greyer and duller over time.

Knowledge around correct installation methods, storage conditions, and restorative and protective products, however, will not only avoid discolouration and keep your lead shiny, but can also bring lead back to its former glory and rid any unsightly stains – regardless of your choice between the two manufacturing methods.

Patination oil and cleaning gel are two prime examples, and products that should be at the top of a roofing professional’s wish list.

Our highly effective cleaning gel works to remove dirt, grime and stains on lead. When applied with a nylon brush or fine wire wool, even very old or ground-on stains can be removed, quickly restoring lead to its natural lustre. This includes light white carbonate stains, caused by lead having not been treated with patination oil, and orange oxide stains, often caused by lead sheet being stored in damp conditions. As such, we always recommend lead be stored in a clean and dry area, ideally off the floor, to avoid trapped moisture between the layers.

If heavy white stains are present, this may be the result of acid cure sealants, which as well as causing stains, can damage lead work. If the lead is fairly new, we recommend removing the sealant, and using a non-acid-curing sealant or traditional mortar.

Once you’ve dealt with the stain and thoroughly cleaned and dried the lead, it’s always advisable to treat the surface with a coating of patination oil; a product developed by the UK lead and building industry specifically to prevent white staining.

For more information on our range of products that work to protect, maintain and restore lead, click here.