Polyether MS polymers, the latest derivation in the development of caulking and sealants needed to support today's high tech building trades, are neither urethane nor silicone. Instead, they combine the best qualities of both-and contribute some of their own. They skin over and cure faster and deeper. They are soft and flexible, tool easily and exhibit very high adhesion and durability. They can be applied at lower temperatures. And they are competitively priced between urethanes and high quality silicones.

What polyether-based sealants do not do is emit odors or shrink. Unlike their predecessors, they are entirely VOC-free and carcinogen-free, and they conform to California's Proposition 65.

"The existing sealant had failed in areas along the six window panels on the dome, allowing water to infiltrate into the interior of the building," Villers explains. "Preliminary investigations indicated that the joint backing was soaked with water on some of the window panels. I chose DuraLink for several reasons. Because it is a polyether, I didn't have to be concerned with out-gassing like I would with a urethane sealant. Because of residual moisture that was sure to be present in the joint interior, I needed a high quality sealant that could handle these joint conditions and not be adversely affected by low amounts of interior joint moisture. I knew that the product would bond well to the aluminum window frames and to the concrete wall panels. I had even run test beads on Kynar-coated metal with the product and was surprised to see how well it bonded. I thought only silicones would bond to Kynar-coated metal."

Villers also was concerned about disrupting normal business operations during the repair work. "I have been on projects where some sealants used had a noticeable odor. DuraLink is virtually odor-free and can even be used for interior work. Another advantage with this class of sealant is that it is 100 percent solvent-free and VOC-free, which means that the sealant bead can't shrink." After the contractor applies the sealant, nothing will evaporate off into the atmosphere and the joint will maintain its size.

Another important part of the project was waterproofing the concrete dome and the window panels. "DuraLink is paintable in 24 hours, which makes it a very versatile product," says Villers.

The job was awarded to Casey Jones of Advanced Coatings, Akron, Ohio. "The most difficult part of the job was having to work from ladders for the entire project," Jones comments. As with any project, the surface preparation is the key to a successful application. "I spent a lot of time removing old sealant and trapped dirt from the interior of the window panel joints. Fortunately, the process was much easier in the sections where the joint backing was saturated with water." The hard plastic Field Pack pail with the metal handle (that holds16 tubes of the sealant) also made the ladder-based task easier.

This project was Jones' first time using DuraLink. Asked for his assessment, he responded, "Knowing that the interior surface was slightly damp in areas, I was surprised to see how well this sealant bonded to the concrete on the interior of the joint, and surprised to see how fast it became tack-free. I was also concerned about the possibility of pending thunderstorms raining heavily on freshly applied sealant, causing outgassing and compromising the bond. I spoke to the manufacturer's technical manager and was told that rain on freshly-applied DuraLink would not harm it at all. It skins over quickly and rain would simply speed up the moisture curing process and result in a faster tack-free time. DuraLink guns and dry tools easily. I'm sure that I'll use it on other projects."