Yeah, that clay might just do it. Might even get into the grooves. I have some by "Mothers" but like Garcia said, they're all pretty much the same.
Again, as Phil said, they should be insured, and are responsible so don't feel bad about saying something to them. As for waf? That's between you and your wife, but I don't hesitate to remind mine that I live here too, and that means WAF equals "Will approval factor" as much as Wife approval factor. Just sayin...