To earn an ASTM C920 rating, sealants undergo rigorous laboratory testing to verify their long-term durability:
The sealant must withstand cyclic joint movement (e.g., ±12.5%, ±25%, ±50%) without cohesive failure. Class 25 (25% movement) is the default minimum unless otherwise specified. To earn an ASTM C920 rating, sealants undergo
Confirms the sealant won't "bleed" oils that could stain porous surfaces like white marble or limestone. Why It Matters To earn an ASTM C920 rating
Gunnable sealants that stay in place without slumping, making them essential for vertical surfaces like wall expansion joints. 3. Class: Movement Capability To earn an ASTM C920 rating, sealants undergo
: Specifies compatible substrates and environment conditions.