I have a Franke granite composite undermount sink that was installed about 2 1/2 years ago. I just noticed that it has developed a crack. Franke has agreed to replace the sink under the lifetime warranty but I have to have the granite installer do the replacement (at my cost). Unfortunately the installer cannot get to it for several weeks. Is there any type of epoxy or special type of silicone that I can use to seal the crack for a couple of weeks? I talked to customer service at Franke and they were not very helpful.