Development of C1736
C24 Representative #1—In the mid 1990’s, ASTM committee C24 decided that the industry needed a Standardized Practice to evaluate adhesion of installed weatherproofing sealants. Such a practice would have applications in new construction for quality control, existing construction for service life evaluations, and in-field “forensic" determinations of air and water infiltration sources. The result of this effort was C1521, first published in 2002 .
C1521 contains both destructive and non-destructive methods to evaluate sealant adhesion. The non-destructive method only looks at small areas of the sealant installation, providing a snap-shot of the total. The later added (2008 revision to C1521) ‘continuous procedure using rolling devices’ can be used to obtain a larger picture of the installation. However, the committee decided an additional stand-alone Standard Practice was also needed for the rolling device method. With the passage of C1736, we now have two standards for in-field evaluation of adhesion of installed weatherproofing sealants.
C24 Representative #2—The committee did a good job of writing this new standard; there were enough “controversial" points of view that a really good standard was produced. The wisdom of the ASTM process shines through in it, because if it was left up to a single individual, or a group of individuals with like thinking, it would not be as balanced as it is; it is balanced due to the diversity of thought reflected within it.
C24 Representative #3—I have come to appreciate the high level of due diligence that ASTM provides, with all of the relevant stakeholders participating in the development and review process. Sometimes we wish that the process could go a little faster, but the net result is very good standards. In addition, once a standard is published, it will be reviewed once every seven or eight years to reconcile it with changes in the industry, and if needed, the standard will be adjusted to reflect those changes.
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General Implications of C1736 for the Industry
C24 Representative #2—Rolling devices are able to provide information that goes well beyond the joint appearance; sometimes joints look bad on the surface, but are good underneath, and vice versa. Joint geometry, twisted backer rod, and other anomalies can be discerned when using these devices; but, the intent of the standard is focused on adhesion. Due to the high elastic recoverability factor of many performance sealants, complete bond line failure can exist and one would never know it by looking. The intent behind the methodology of C1736 is to facilitate complete and durable building seals.
Applicator—I am skeptical regarding the ability of this test method to reveal the entire picture; there are many factors that go into a wall design, and therefore many different problems that can develop. It is my position that the best place to put extra effort is into applicator education and training – applicator certification ideally – to prevent sealant problems in the first place. I am also apprehensive regarding potential mischief that could be dredged up from such testing, costing everyone unnecessary time and money. Therefore, those using this test methodology (of C1736) should have good knowledge, expertise, and intent when using it so as to prevent misuse.
Consultant—I have been using the screen roller procedure for at least 15 years, and it is the number one tool I use because I want to know everything that is going on in that sealant joint. I place a piece of easily removable painters’ type masking tape alongside the joint that I wish to analyze; I have the roller in one hand, and a felt tip pen in the other. As I roll along spot to spot in the bead, where it pushes in easily, I put a mark indicating that the sealant is very thin; when I come to a spot where the roller does not push in, I indicate on the tape that the spot is hard, heavy, or thick; when adhesion has failed, I indicate that on the tape as a line showing where the failure starts and stops. When I am finished with a specific area, I put a label on the masking tape and take a picture of it, for the record and for future analysis. This provides information that can identify systemic problems when specific issues are found to be repetitive, or share commonality. While the standard is written as a test for adhesion, much more information can be derived from its’ use. A screen roller combined with a good marking and data archive system form my number one diagnostic method when conducting sealant forensic analysis. I can teach and have taught others how to use this methodology in less than an hour.