HB42 Ultimate ‘All-in-One’ Sealant & Adhesive Seals, Sticks & Fills. Based on the new generation of advanced hybrid polymer technology for outstanding adhesion and strength. HB42 can be used inside and outdoors, from sealing bathrooms to guttering. Unlike other sealants and adhesives, HB42 is odourless, anti-mould, food safe and has been GEV approved, recognised for its very low emissions.