Butyl Tape & 3MM 4000UV

TonyG13

@LaRea - Interesting, and I'm still confused.

With the "Butyl tape" product videos I've been watching (such as the ones for the "Bed-It" tape @YYZRC recommended) they demonstrate peeling off the tape and rolling it in a ball to surround the screw head to bed it in place, just like plumbers putty.

Here's a link to that video: https://marinehowto.com/bed-it-tape/

And in the reviews for the "Better Boat Butyl Tape" they basically show the same thing. People using it as a "tape" to bed in a window, etc., but then also using it as a "putty" by shaping it to their needs.

Some of the product descriptions say they are a mixture of silicone and butyl, but maybe these are just modified forms of plumbers putty that they claim as "butyl?"

YYZRC

I tried the butyl tape and found it frustrating to use. It's Sikaflex 295-UV for me.

LaRea

@TonyG13 -- on that page from Bed-It, the critical point is that they don't twist the screws.  Those screws have backing nuts on the inside.  They twist only the nuts - not the screws.  Toward the bottom it says:  "Have one person hold the screw head with a screw driver to keep it from spinning then go below and install the nut and washer and tighten it down."  

I've tried using butyl for screws with no backing nuts.  No workee.  For that, you need a liquid product such as Sikaflex or 4200.  

Here's the beauty of butyl (hah!):  if you ever need to remove the fitting, the only tool needed to remove the sealant is your fingers.  Or maybe dab it with a little piece of fresh butyl, and it comes right off.  

Generically, butyl is a type of "putty" because you can mold it with your fingers, but it's definitely not the same as plumbers putty.