Butyl Tape

[ebb]

1/16"x1/2"x50' -- (non-marine price: $5.97 = $0.17ft incl shipping) in black or medium
grey. (3 rolls = 17.91, S&H 7.59 = 25.50.*) In terms of chewing gum, Bed-It equates
with pink Double Bubble, Tremco with light grey Beachnut 5. Aggressive Bed-It holds
together much more tenaciously than normal butyl tape. The metaphor coheres, in this
case, also because both caulking and chewing gum, strangely enough, are the same
material... but perform quite differently, except under tables and theater seats. Don't try
this: you could blow giant bubbles with Bed-It, but not get one even started with Tremco.
Will compare the two in a simple adhesion test later, and report back results to this post.

IMCO
In regard to butyl tape use under water** in constant immersion, as suggested earlier:
regular butyl tape used between two surfaces, with an exposed edge, would work as well,
but preferred over any gungrade rubber for underwater sealing of metal or plastic fittings
to fiberglass. Especially regarding a thruhull that is backed by a valve like a seacock. Main
arguement behind this is that the fitting will not end up bonded and impossible to break
free to back out next time.


Dolfinite is not sold with the same underwater caution. Its label says it's intended for
construction of double planking in wooden ships, which implies that the compound is not
exposed to direct water contact as an open seam. Still, imco, Dolfinite Bedding Compound,
altho not sticky by any stretch, as a very cohesive paste, could be used equally well, for
example, under the same thruhull flange fitting for a seacock.... as beechnut butyl tape.
BUT, waitaminute:
Old time Woodenboat forum guys complain that ever since pentachlorophenol was out
lawed, Dolfinite hasn't been the same. It hardens in the can. Was Woolsey's Dolfinite,
now it's Pettit's 2005. In 2005 the new owner probably added driers to the formula, so
they could brag on the label that, 'when it skins over, it's paintable.' It's not the same ole
Dolfinite. Used to loosen it up with raw linseed oil when it got too stiff. Old stuff probably
was simply l. oil and calcium carbonate. Modern Dolfinite, by concensus, gets hard.
Tech data sheet says 5-10% xylene/mineral spirits, but no clue what the compound is.


Butyl Tape (NOT gungrade butyl) is sold as already cured rubber, requiring no cure time.
This will be the only reliable rubber caulk to keep in a cruiser's bosun's locker.
Gun grade, 10oz tube, butyl contains volatile solvents, and will skin over. May be usefull,
but is a different animal than the tape. Has little or no shelf life aboard, and, as with the
polys, uses an awkward tube gun that will find no space to store on board, anyway.
A piece of butyl tape can be pushed into nearly any cranny to stop a persistent leak!
Keep it away from petroleum products and containers!
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**Butyl tape underwater - SailNet 4-06-2009 Thread
"I work with with underwater bouys that are deployed as deep as 2000 meters. The main
body of these bouys is composed of a glass sphere that comes in two parts. Hemispheres
are mated, a light vacuum is applied, and we seal the outside of the joint with standard
off-the-shelf glaziers butyl tape. The tape has remained intact, pliable, and removable after
as long as two years submerged. Scotch Super 88 electrical tape is wrapped around as a
mechanical protectant.
Bouys are recording devices for marine mammals. We usually deploy them for 3-6 months
where they record sounds in a pre-determined frequency range onto harddrives. The data
is extracted and analyzed to research whales mostly. My job is building/maintaining these
recording devives, as well as going into the field to deploy and retrieve them for the
deployment team of the Biocoustics Research Program at Cornell University."
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*ordered from: Reflect Window & Door, Edmonton, AB -- 11/16/2015
http://www.reflectwindow.com/Tremco
(I've sat in the cockpit on warm days unrolling butyl tape. Must use the paper backing
to control the tape. If you try to pick it up when warm, it will deform. If you are sealing
longish pieces you want to start with a single known thickness, don't want to stretch it.
Warm tape will squeeze out. You can trim the squeeze out anytime in the future. It's
inexpensive enough to order a choice of thickness: 1/16. 3/32. 1/8. On colder days, or
from the ice chest, the 1/16" is manageable.
Cut lengths with your Friskars, try not to handle it, gets sticky.)

"Tremco 440 Tape is a 100% solids polyisobutylene cross-linked butyl preformed sealant.
Unaffected by UV thru glass....Not for use in joints subjected to continuous water
immersion..." Tremco data sheet. There are more aggressive commercial butyls that are
used underwater. They are part of systems, Like waterproofing butyl may have a foil or
EPDM backing. Seems like the do-not-use-underwater caution is more legal than practical.

Gungrade synthetic rubber sealant/adhesives must CURE, change from paste to a flexible
solid adhesive. These tube monsters are notoriously messy to use. However, clean,
unchanging butyl tape's 'other' quality is that it can removed fairly easily and quickly
without solvents and profanity, by self blotting, pulling it off ...when the body of the
sealant is fully exposed, as on the work of a project. Butyl is in a class by itself. It is,
compared with all others available, a perfect rubber for many uses aboard.Tremco
sealant, captured in an assembly, will be perfectly safe for decades underwater. imco.
Don't use Bed-It on threaded portions of screws and bolt-shanks. Be aware of its strong
adhesive quality. Be selective, it may be unnecessary for many applications. But great
to have for an emergency. Use Bed-It on the weather side of an assembly....don't bury it.
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Other marine type B.T.: Sailrite #180 Trimmable BT, offwhite, 1/16x3/4x45' -- $0.26.5 ft.
LifeSafe Butyl Caulking Tape (pre-pack) white - light grey, 1/8x3/4x20' -- $1 ft.
3M Weatherban Ribbon Sealant, black, aggressive, 1/16x1/2 or3/4-1"x50' -- $0.75-$1.35 ft.