Butyl-rubber caulk works best on concrete, concrete block, brick, stone, gutters, flashings and chimneys.
From the post-gazette.com
It is lined with a thick pad of foam rubber covered by a butyl-rubber sheet, which is sealed around the edges.
From the newscientist.com
Flexible liners are usually made from PVC, butyl rubber, LDPE or polythene, while rigid ones are fibreglass or hard plastic.
From the expressandstar.com
The world's second-biggest maker of butyl rubber plans to raise operating profit 75 percent by 2015 as it adds capacity in Asia, Germany and Brazil and buys small and medium-sized companies.