Tags: #architecture #buildingdesign #buildingscience #materialsscience #tape #water

How long should tapes seal under immersion? 5 hours, 24 hours? 7 days?

Tapes are typically assessed on the bases of peel adhesion per AAMA 711. Again the bar is set low at 1.5 lb/in (24-hr dwell time). The same expectations are sought after 7-day immersion – albeit on anodized aluminum. But can tapes truly seal for such long durations on real-world substrates such as acrylic coatings, sheet membranes, and integrated WRB panels? 

It’s important to realize that what we currently seek is a rather modest peel resistance on anodized aluminum – not water sealing on paired WRB substrates. Although 7-day immersion seems daunting, it is actually nothing of the sorts when considering peel adhesion of just 1.5 lb/in and the fact that sealability is merely assumed, not tested.

Here I use a modified version of my ponding test (0.17 inch of standing water) to assess sealing at tape-substrate interfaces. Water indicator paper is encapsulated by the tape to serve as a visual aid for potential failure. 

What I’m finding confirms what I’m seeing in face columns and other methods such as spray testing. Many substrates pose major challenges for tape sealing even though the tape itself may still pass AMAA’s criteria. Porous substrates and complex micro-topographies pose the greatest problems. And for many combinations of tapes and substrates, 7-day sealing is simply unrealistic.