Orange Backer Open Cell is a medium density, firm, open-celled foam for supporting sealants in movement joints. It can be stretched, squeezed or bent to conform with irregular surfaces. Because of its resilience and co-efficient of friction it will remain as placed.
Open cell polyurethane foam is to be compressed at a minimum of 25% and a maximum of 75% when placed in joints to be sealed. This one size of foam can be used in a much wider range of joint sizes than one size of closed cell polyethylene foam backer rod.