Previously, we wrote about our suggestions regarding joint sealants and StoneLite® exterior stone facades (Link to corresponding blog post). But a special consideration, in addition to our previous recommendations, concerns sealant bubbles and how to avoid them with your stone facade.
Silicone sealant can cure or firm up, when exposed to air. Should this curing process progress especially quickly, because of excessive moisture or because of high temperatures (around 120 degrees Fahrenheit or higher), small gas bubbles can begin to form. These bubbles can grow in size rapidly, should excessive heating occur before the sealant can cure.
These sealant gas bubbles happen most regularly in instances of damp weather. Alternatively, you may also see these bubbles occur around your stone facade if the area is exposed to direct sunlight. Therefore, sealant bubbles are more often seen in late winter or spring. It’s important to note that it’s possible for darker color stones to reach temperatures in excess of 160 degrees Fahrenheit, despite the fact that ambient temperatures may only be near 80 degrees Fahrenheit.
Specifically, Dow Corning 795 Silicone Building Sealant includes in its product information that their product shouldn’t be used when surface temperatures exceed 122 degrees Fahrenheit or on frost-covered/wet surfaces. No matter which kind of silicone sealant you intend to use, it’s important to consult respective product information for similar specifications as the example above.
In addition, sealant bubbles can occur in instances where a closed-cell backer rod is incorporated. This is due to the fact that the skin on a backer rod can be easily torn, allowing gas to penetrate the sealant around a stone facade. For this reason, we recommend using an open-cell backer rod.
As a final note, silicone sealants (in general) carry a shelf life of about a year; assuming they’ve been stored properly in temperatures below 80 degrees Fahrenheit. As you can see, avoiding sealant bubble with your stone facade is all about avoiding the scenarios in which they are likely to occur. Have a question about sealant bubbles and your stone facade? Leave us a comment or email firstname.lastname@example.org