SIS 440 is TDS's flagship marine deck caulking compound — a one-part, neutral-cure formulation trusted by professional boat builders and refit yards worldwide for over 35 years. It forms a permanently flexible, UV-resistant bond in teak deck seams with no primer required on properly prepared seam walls.

Unlike two-part polysulfide caulks, SIS 440 cures predictably, resists sunlight and saltwater degradation, and remains pliable through thermal expansion cycles. Available in black, gray, and white to match any deck aesthetic, SIS 440 is supplied in both cartridge and sausage formats for jobs of any size — from a single seam repair to a complete deck re-caulk.

For best results, pair SIS 440 with TDS Bond Breaker Tape at the seam base (to prevent three-point bonding) and use a professional-grade sausage gun for consistent bead pressure. TDS-trained installers use SIS 440 on every teak deck project leaving our Sarasota and Barcelona facilities.