I think the butyl I have is more like 1/8". I'd love it if it was 1/16" as half of it squeezes out--but at least at that point you can be pretty sure you've got a great seal there.
A couple of things about butyl I've found lately:
* When working on an overhead bolt that hangs straight down, a dot of butyl on a washer will hold it there temporarily while you are trying to get that nut on there.
* Mineral spirits gets it off your fingers and other surfaces if necessary. This is especially handy when your fingers have reached critical mass of stickiness, turning you into spider man.
2000 Beneteau 331
Northern Chesapeake Bay
Ambition is a poor excuse for not having enough sense to be lazy ~ Steven Wright