Industrial and STP
Silyl-terminated polymer sealant for metal, plastic and glass — primerless and paintable.
Choosing one
Choose STP for exterior panel joints and mixed substrates, not for structural load. KAM921 is UV-stable, paintable and primerless on most metals at 1.8 MPa and Shore A 40, which is roughly half the tensile of a glazing PU. If the joint carries load, this is the wrong family.
Where it goes wrong
STP fails on load, not on weather. A panel joint that looks fine for two years can creep if it was sized for movement but loaded in shear; the same bead on a structural bracket will not hold 1.8 MPa for long. Keep STP on movement, and use a structural adhesive where the drawing says so.
Shore A 40 is the handling number. It is soft enough to tool with a spatula and firm enough not to sag on a vertical panel, and the 450% elongation is what lets it follow thermal movement without peeling at the edge.
Decision table
| If | Then | Because |
|---|---|---|
| Mixed metal, plastic or glass, outdoors | KAM921 | primerless on most substrates and UV stable |
| The joint carries structural load | a structural adhesive | 1.8 MPa is a sealing figure, not a bond strength |
| The bead will be overpainted | KAM921 | paintable once fully cured; test the topcoat |
| Permanent immersion | not STP | hydrolysis risk in continuously wet joints |
Read before you specify
Other families
- Automotive glass bonding — Windscreen, side and rear glass adhesives — 310 ml cartridges, sausages and 200 L barrels.
- Body and sheet metal — Seam sealers for body panels, doors and container joints — sandable, paintable, four colours.
- Construction joints — Concrete, tunnel and drainage sealants — 550–615% elongation, elastic recovery up to 80%.
- Wood and glulam — One-component PUR for engineered timber, glulam beams and sandwich panels.
- Activators and primers — Surface preparation that decides whether the bead holds: K-901 activator, K-801 primer.