Rationale

There are two types of edits. Some edits are editorial. The other edit is the addition of a category for stain testing. A higher probability of substrate staining has been demonstrated when a sealant is compressed under accelerated aging conditions. This also more accurately represents the condition in which a sealant may be exposed to while in use. Within the ASTM standards there are two staining test methods – 1) C510 Standard Test Method for Staining and Color Change of Single- or Multicomponent Joint Sealants and 2) C1248 Standard Test Method for Staining of Porous Substrate by Joint Sealants. Discussed in the January 2024 C24 meeting, C510 does not incorporate sealant compression and is better quantified as a sealant bleed test (where bleed is defined as the movement or diffusion of a sealant component such as plasticizer, monomer, unreacted polymer or other formulation ingredient to the sealant surface or substrate) rather than a stain test. C1248 is more rigorous in that it does incorporate compression and is viewed as the industry standard for determining whether a sealant will cause staining to a substrate. As such, it is recommended that ASTM C1248 be incorporated where stain testing is needed instead of using ASTM C510. It is recognized that not all sealants need to be non-staining. Therefore, the creation of two categories – one where stain testing is not needed/critical to the application and one where stain testing is important would provide further clarity to the industry.