Butyl Tape

[later edit: later posts generally have more up-to-date info]
OFF-WHITE trimable butyl rubber tape is hard to find.
Some sources are not clear about the difference between putty tape and butyl tape NOT interchangable.
Putty tape is never used on a boat, it is oily and gets hard. Butyl rubber tape stays sticky & pliable forever.
Butyl rubber tape throws no oil and is impervious to water.

Getting ready to mount the lexan slab-on windows to the cabin side.
Positive I will attempt white tape for the frameless 'slab-on' lexan lights to the cabin.
Will also use it to imstall flanged Bomar hatches.
Use it between fiberglass and any metal hardware. Use it for seacocks and thru-hulls.
More common gray or black butyl tape can be used here.
It stays sticky forever and gets stickier as it ages.

Butyl is not adhesive. You will always be able to remove it.
Read on the net there is a growing cadre of skippers who have rediscovered this material.
It's imco a much better all-round caulking material than the highly advertised and expensive marine sealants.

The tape is used to make a thick controlled seam. It is difficult to squeeze the stuff out when something is flat against flat like a cleat base.
We're using the caulk to make a rich waterproof seam. It is a sticky clay-like substance so it is possible to squeeze 90% out with the sustained clamping action of bolts. You want caulk to remain in the interface. You can insert an EPDM rubber washer or O-ring on your fastening as a spacer in the caulk to help keep a 'butyl line' while cinching up the work.
The butyl is softer as temperature rises. As you unnroll, the cooler it is the more likely it will keep its shape. If you pull and stretch it, which it likes to do, it gets thinner.
You can stack the tape. make seams by overlapping,
but it can take considerable force to to get squeeze-out, but not too much squeeze-out.
There is a bell curve. Most flat tape can be teased around corners (like our cabin windows) without distorting it too much.

Your heirs will be able to take anything butyl apart without consigning you to the depths of hell.
So if you do manage a leak it is relatively easy to take the damn installation apart again.
Have used tube butyl in conjunctiion with tape butyl. Won't use tube butyl to mount anything.
Because it is less stiff and will act like polysulfide and polyurethane caulks which, as you know, gets squeezed too thin with very low pressure from fastenings.
Tube butyl is cleaner to use, wipes up with mineral spirits, the whole exercise is less messy than with synthetic rubbers. A tube of roofing butyl will set you back $4, not $24.
The 1" wide butyl tape we've just ordered (3/11) comes in 30' rolls for $7.

Elixir Trimable Butyl Tape 180
off white 48462 1/8" X 1" X 30'
Recreation Vehicle Accesories.
Denver, Colorado

There are other widths and thickness.
Trimable means you can cut the squeeze-out away with a plastic spatula, something that comes to an edge but isn't sharp.
Some butyl tape used for roofing comes with plastic cloth inside. That you can't separate without a knife, and you don't want to do that. Also becomes messy.

Once got butyl tape from an RV supply that charged me 3 times over what the above supply did. Shipping was MORE than the product!
Also, pleasantly, R.V.A. came with a very knowledgable and friendly order taker.
The overcharge source shipped in a carton that allowed the tape to get badly smooched out of round which makes it a PITA to use. Glues the release paper and concentric layers together.
It's difficult to ship - so ask for careful packaging.

Thanks Ebb, great information.

If it's too cold some butyl tapes don't stick very well, especially on vertical surfaces. You can use a propane torch to lightly heat up the side of the tape you're going to stick down. Be careful the stuff catches fire easily.

By coincidence I was using butyl flashing this morning on a architectural project I'm working on.

Must be COLD where you are, Ben!
But no doubt it will warm up.
And it will stick then, no problem.

There definitely is a learning curve to butyl.
It never 'dries' but it's flamable - so it can't be offgassing solvents.

And on that score did a bit of research on tube (cartridge) butyl, a different animal than tape butyl. For which I have never found a caution on its use for glazing polycarbonate.
Found no tube butyl that doesn't have a good quantity of solvent in the formula. No 100% solids butyl!
Therefor when installing lexan you better watchit if you want to, say, juice the fastenings as you push them in with a squirt of liquid butyl.
Have found one tube butyl by Surebond - SB-140 Skylight and Window Butly Sealant - that is loaded with Aliophatic Hydrocarbon solvent and a small amount of Toluene.
Supposedly neither of these attack polycarbonate
which has an impressive list of chemicals and cleaners we can't get anywhere near the plastic (including Cheer Detergent!:eek:) You can get this white butyl cartridge on line at bestmaterials for $4.

MaineSail/Compass Marine, who has the excellent photo-how-to-blog has some butyl tape for sale here (tips on how to use it in his blog above): http://www.pbase.com/mainecruising/butyl_tape

Looks like he's got his own maintenance forum going these days too: Musings With Maine Sail

Quote:

---

Originally Posted by mbd

MaineSail/Compass Marine, who has the excellent photo-how-to-blog has some butyl tape for sale here (tips on how to use it in his blog above): http://www.pbase.com/mainecruising/butyl_tape

Looks like he's got his own maintenance forum going these days too: Musings With Maine Sail

---

Thanks Mike!

Here is a guy I would trust my boat to!
That is if I could afford it! That's why DIY
And this is an extraordinary site for that.
As one fan put it: It's exactly what the internet is all about.

Believe one claim to fame is his irrefutable logic explaining butyl tape to idiots.
But just as important is his amazing JIMINY CRICKET photos of the process.
As he takes us through actual work in progress, there is this little fellow who takes those amazing close-ups....
It's doubtful that any conscious adult won't be converted or miss doing the project correctly!

One testimonial by a boatyardman 'Joe' who laments that even tho he
shows and tells skippers what is correct, they don't listen. The light doesn't go on. I see it at the yard too.
Maybe part of the edjucation problem is that owners and crew want to appear like they know what they'ere doing. And they're rushing because of the yard fees.
It is that they CAN'T listen.
Can see nodding heads followng Mainsail's reasoning on mounting deck hardware, for instance, and bet the fools will find themselves at the local marine shoppe buying a tube of techno poop because that's what's available, and pricey, and it's macho. And they don't sell no cheap roofing junk there, anyway.

With MainSail, we and our boats will prevail!

With Casey, it is that he is a generalist - not very specific or detailed.
Good Old Boat is sometimes another source of questionalble project information,
along with Practical Sailor who are myopic mainstream product orientated.
Not always off, there's good advice, but it often doesn't seem to be informed, innovative or consequential.

Who has OUR best interests?
(MainSail is the only source I've seen with a great tip for butyltape cleanup. Actually I thought I invented it. Take a a wad of the squeezeout, which is very sticky to your fingers - but after kneading it a little it stops sticking and then you use it to blot and pick up up all kinds of butyl bits and pieces and scrappings on your work - you'll see!
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later EDIT (9/2012) Got all kinds of butyl tape over the years, mostly from RV suppliers, who invaribly package it so that it arrives smooched & squashed & unusable.
Finally located what imco is a very good NAME BRAND butyl tape product from GSSI Sealants. Family owned, independant, 30 years in business. Sealants are manufactured in Piedras Negras Mexico and shipped out of Houston.
Now have a carton - of perfect rolls - of gray MB-10A Sealant tape. Got used to 1"wide 1/8" thick stuff. The butyl tape compared to brandless others has 'greater cohesive*/superior adhesive strength, withstrands higher temps, cold flow & UV resistant, anti-fungal & anti-bacterial. And comes in 39 standard sizes.' GSSI makes a separate line of RV tapes also - but decided to stick with what I got stuck on.
Silicon paper interleaved - the crinkled paper on brands I've tried sticks to the butyl. Silicon paper allows you to press the tape on a surface - and to flatten it, mold it, if wanted - then peel the paper off. White, off white, having used it, now imco is not practical on a boat. Black may be better, but my choice is gray because neutral medium gray would be instantly recognized as butyl (rather than a forgotten whatever white or black tube rubber.) White stuff I've used, because of the "butyl-line" between surfaces, is open & sticky for a long time - picks up dirt and dust - gets grey anyway.
Look up the product specs, data sheets.
__________________________________________________ __________________________________________________ ____________
* this is an important attribute. Some of the extruded tapes I've used had little or no handling integrity, meaning that as it is separated from the paper it elongates and stretches - pulls into a skinny version of itself. Imco, it's important when putting a butyl system together that the material stays at its roll thickness while fitting. (On warm days at the project site, it helps to keep the butyl tape on ice in a cooler.) You buy tape in the thickness that suits your project. Thicker stuff holds its shape better for me. Tape that is too loose will also squeeze out unevenly. Use the fasteners in a project like portlights to do a controlled squeeze out. Being eternally non-hardening you can count on it to squeeze out how you want it to (using limit washers & O-rings.) Squeeze out makes the waterproof seal. Use the brand tape that will keep its dimensions for as long as it's handled. And for as long as it's doing it's job in your project.
Always know where your butyl is......:p
__________________________________________________ __________________________________________________ ____________
later EDIT: Butyl tape amalgamates (fuses, combines) with itself, no problem. 1/8" thick tape is really TOO thick for most uses on a boat.
3/32" tape is the max thickness easy to deal with. There will probably be an over abundance of squeeze-out anyway. 1/16" inch thick
butyl can be stacked NO problem what-so-ever. Material is so sticky that laying one strip edge to edge, or on top will instantly become one.

Mainesail CompassMarine recommends using butyl tape under stanchion bases.
Assume stanchions themselves will sometimes act as a lever and tweek the base.
Butyl in theory is not a setting sealant. Altho in use, time will stiffen it considerably.
It is pre-cured. Doesn't need a catalyst. Moisture or solvent evaporation doesn't
SET it. Brands vary, but it is what it is. Won't create a gasket unless you design
a surface to capture the material and keep it from squeezing out of the joint.
Chamfering fastener holes to create sticky washers is one method.
(see MaineSail's photographic tutorial on mounting hardware, CompassMarine site.)

Butyl is a far superior sealant than gungrade tube rubbers: polysulfide, polyurethane,
and polyethers formulated with solvents. These synthetic rubbers create problems if
they fail, leak, or need to be removed. Seems that the nature of the beast: stanchion
bases, cleats and chocks, winches.....will need maintenance every once in a while.
Butyl caulking can be refreshed without becoming a federal case. Butyl tape seems
clean and doesn't stink....compared with gungrades... And I've said before that
chewing gum is a 'foodgrade' butyl. [that's why I don't chew gum!]

Now this may not be news, but if you want to have access to stationary 'working'
hardware, why not try to make it easier to take apart? Stanchion bases: Maybe
install the bolts inside out, nuts outside, so the base cab be pried off with bolts in
place. Bed bolts well in backing plates and holes and the base of the stanchion.
Bed everything thoroly in butyl, including threads.*
*This is not a good idea using MaineSail's BED-IT brand butyl tape. See post #10.

Some fittings like mooring cleats require full strength on the bolts, heads outside.
But still all butyl, so that there'd be no question that the fitting can be rebedded.
Inaccessable fastenings like stanchion bases have at the Ariel cockpit aft will benefit
with reversed bolts if the backing inside is beefy, watertight, & permanent.
.................................................. .................................................. ......................
We have been advised to make sure there is a visible glue line in an installation.
Isn't going to be possible all the time. Have used O-rings and plastic washers to
hold the fitting off the surface....a bit. Think this works with butyl better than any
gungrade rubber that advertises its flexibility when set, but don't tell you that when
cured the rubber is no longer sticky. They may be irrevokably bonded to one or
both surfaces - yet are known to 'break' or crack...and leak.

When butyl is pulled apart with tremendous force, both surfaces still will have
butyl sticking to them. There'll be sticky stalagtites and strings attached to both
surfaces. Likely have to jam a thin putty knife between surfaces....because they
will SEEM to be bonded. It is.... the butyl sealant bond - not structural adhesive.
Mineral spirits is the butyl solvent...dipping the blade might be useful.

Butyl is still capable of sealing when squashed to a thin film. And we are warned
not to use it UNDERWATER. MaineSail doesn't recommend it. Hard to fathom what
reason the Butyl Lobby has on this subject, except that butly is not an adhesive.

I use b.t. with thruhulls. Only first few threads under the flange. There is little
if any seam contact with active water by the butyl. What reason for the warning?
Tests? Cannot find them. Butly tape retains sealing and stick under severe
weathering conditions - water causes no breakdowns, voids, cracks, or separations.
Most important is whether the system can be unscrewed or unbolted....uneventfully.

Butyl rubber cold fusion electrical tapes are the best and only long lasting tapes for
UV and weather proofing marine electrics.
.................................................. .................................................. ......................
NOT BUTYL:
CHEM-LINK POLYETHER (has green certificates). A gun grade urethane/silicone
hybrid worth checking out. No VOC, no solvent, hardly any odor, no off gasing, high
bonds on a wide range of materials. Isopropyl alcohol cleanup.
Solvent formula polyethers are being discontinued.
M-1 MARINE structural Adhesive/Sealant (Why call 5200 or LifeCaulk 'sealants' ?
This is an adhesive. Underwater total immersion rated. Have used M-1. It's easier
(less messy, less viscous) to use than toxic solvent varieties. ChemLink lists
applications for portlights, deck fittings, moldings, fiberglass. But DON'T DO IT......
unless you really have to glue fittings onto your boat.
(Some published inconsistencies exist viz 'weatherability', UV resistence. I feel this
stuff sets too hard & stiff to be used as ChemLink advises, except for thin seams.
Good for heavy horizontal seams, built-ins, bulkheads, non-removable structural.

NOVALINK: a more flexible polyether sealant capable of 35% extension and
compression joint movement. Range of colors. Apply in damp, cold, or dry
conditions down to freezing. Aluminum, galvanized, engineered plastics, glass, FRP,
Foam. Polycarbonate friendly. Not rated for total immersion.
DURALINK: "extremely elastic sealant used in metal archetecture for joints subject
to movement." Havn't tried it yet. Get my poltyether from a local roof supply.
About $6.. Informative online ChemLink site.

ChemLink products are synthetic rubber like the toxic cousins - cure to different
gasket-like flexes - retain flexibility but lose their stickiness.
Whether these industrial roofing materials bond better, or weather better than
$$$ recreational boating products is really unknown.... until you&I talk about them.
They cannot be used in continuous immersion....only M-1 Marine.

I rebedded my stanchions last year using the butyl tape - hopefully this year I'll get them out from under the tarp...

Mike, being that you are embarked on practical butyl research.
Maybe you can update us every five or six years on its efficacy as a stanchion tamer.

HAPPY LAUNCHING !

Have a project I thought was ready to assemble: A new clear polycarbonate slide
hatch with a surround of varnished mahogany on top, like a tray. Redesigned
companionway to include a s.s. channel around the entrance a la s/v Atom
...to provide security with s.s intruder bars, and various drop boards.

Assembled hatch with Bed-It butyl tape, and took it to the boat. Fit too damn
tight, altho the dry fit before without bedding was good. Hatch has to slide with
room to spare under the compass mount, framed dead center over the c.way
which is part of a 'new' permanently installed dodger and sea hood. Remedy:
Take hatch apart, shrink height of all the wood..... 'Not a problem with butyl...'

Bit the bullet: Had just gotten two boxes of CompassMarine BED-IT Butyl Tape
from HamiltonMarine (who don't tell you it's MaineSail's) for $25 each, $UPS incl.
$0.50 a foot.
Package arrives, find precious 14oz rolls of 1/16"x1/2"x50' grey tape captured in
very clever individual 8"x8"x1" corrugated cartons that center the mini roll inside,
so tape doesn't arrive smushed and distorted like usual clueless packing. If you've
gotten 1/8"x1"x50' RV tape in a roll before, you know by heft alone - 3-4 lbs -
you got your $6.95 worth. = 4 times more for 15 cents a foot vs $0.50 per ft!
You can access MaineSail's great encyclopedic photo essay on bedding metal
fittings - web address found printed on the Bed-It box:
"INSTRUCTIONS: www.marinehowto.com/bed-it-tape Above Waterline Use Only"

Experience: My trim pieces are wide enough to require two 1/2" side by side strips.
Because 3/8" polycarbonate sheet is clear, the coverage of the butyl is on display
at the interface. The 1/16" tape. as MaineSail says in his article, is quite "thick"
- thick in this case means very firm and not easy to reduce in bulk for customary
squeeze-out. Used spring clamps in attempt to squeeze it 1/32" -- didn't succeed
uniformly. But visible through the plastic, the pressure resulted in an excellent
consistent seal with no bubbles or skips. Two strips seamlessly marrying into one.

Disassembling the hatch: Wholey !@#$%$! Where fasteners go thru the
interface, when backing them out, threads lock on the butyl, screws stop turning
and bolts become welded in their holes. Taking on the trim pieces means
hammering in a stiff puttyknife and attempting to lift them with a gentleman's prybar.
Coated $Lexan can't be buffed to erase the damage I'm doing... jamming in
bamboo skewers and chopsticks to get the process started. Levering up, both
sides of the wood trim, with incredible effort, pulls up a tough snakebelly skin...
that has to be poked & sliced with a utility knife, to relieve the incredible tension.
With loud splitting and spitting noise, the trim tears off leaving gray moonscapes
behind on both wood trim and lexan. Bed-It instantly '5200's' itself to plastic
and varnish - the 1/16" tape tears itself apart between its bonded surfaces.

Removing sticky uber butyl terrain from plastic & wood then becomes the problem.
Tediously push it with plastic tools. Putty knives don't lift the tape, nor cut it either...

Blotting at it with a gob of the same butyl, proves to be the only way to yank it off
cleanly. DRY, no liquids. Actually, you get really good at push/blotting and picking
up every remnant. Raw butyl blotting ball nearly attaches permanently to fingers.
Butyl filled screws and bolts need dissolving soak in mineral spirits for a day or so.

BED-IT-TAPE ... THE 5200 OF BUTYL TAPES.

Don't remember seeing in Bed-It lit, but believe this rubbery butyl is 'crosslinked'.
Actually this stuff is double-cross linked. My philosophy is all boat fittings are
maintenance items. Metal pin fastened, not bonded. Someday I will find myself
removing that stanchion or port. Will it be a bummer with butylful Bed-It Tape.?
Bedding has to be friendly. Use it on plastic access plates or hatches, at your peril.
Anything flanged that you pry to remove is, imco, essentially there forever. Third rule
of B-IT : Never use it on any fastener thread. Under the head? Better NOT.
Remember: normal butyl tape has a rep for gaining bond strength as it ages.
For love of humanity, make sure metal fasteners are easy to back out and remove.
Squeeze-out and chamfer squeeze-ins is a brilliant idea. Think twice before Bed-It.

Trim pieces lagged with small MS need assistance with mechanical clamps during
assembly. 1/16" tape is about the same thickness as some rubber sealing washers.
Why not create a rubber washer dam around bolt & screw seam* holes??
Rather than hard O-rings, which could get shifted in a big squeeze..
Bed-It Tape requires pretty extreme pressure, to move it into sealing mode.
Can say from recent torture, when joining two pieces, fasteners will gather up
this bedding at the interface. Bolts & screws with any Bed-It Tape on them, home
in their holes, cannot be removed without an act of congress.
* yes, at the interface. On the piece arranged with the tape before joining, cut
1/16" rubber washers (McMasterCarr) into the tape with a hole punch or craft knife.
Under pressure it'll create a dam around the hole... right?

Why can't butyl tape be used underwater? ....Anybody have an idea?
ANY butyl tape is impervious to air, vapor & water. (But No resistance to aromatic
and aliphatic hydrocarbons... petroleum oils, gasoline, or mineral spirits.)
Dissolves? Assuming the crosslink, I bet Bed-It Tape works too-well underwater.
Captured between 2 surfaces, edge exposed, and 60F water temp, nothing will
move it, dissolve it, waste it away. Has this total immersion caution been tested?
__________________________________________________ ______________________

Stanchions: Some Experts say you can't... but imco, this one Bed-It Tape can be
used on a well designed life-line installation. Its cohesive elasticity when stretched
temporarily toughens the material. The more it's pulled, the more resistance is
developed. In fact, it probably is the only ideal butyl bedding for 'working' bases,
because of its aggressive adhesion between dissimilar materials. As near lurching-
body-shockproof-bond as any 'removable' rubber caulk could promise. Use could
be extended to other working deck fittings like cleats, tracks. 3M makes an
aggressive half inch wide 1/16" thick black butyl specifically for bedding track.

IF I use it for stanchions, incorporating rubber washer dams in the Bed-It layer to
isolate screw shanks & thread is the way. Use less aggressive chamfer bedding
for FHWS. TREMCO is my choice. 1/16" butyls are easier to use. Stacking the tape
for thickness is instantly fused/melded as one. Perfect for nobbled base bottoms.

Time will tell if Bed-It fries in the tropics or dies in the arctics. Gun grade rubbers
like polysulfide and elastomerics used for stanchion bases eventually oxidize, harden,
die, crack, leak (eternally bonded to gelcoat) and require dis-assembly-from-hell.
.....Wheras, non-steroid butyls generally remain alive, self-healing and mostly
friendly. On deck, remove butylized fittings by first dipping a stout putty knife
in mineral spirits and ease the blade between deck and fitting -- trying to melt
whichever butyl with the solvent. Probably the easiest way.

Bed-It's clever roll shipping box is something special. Haven't tried this yet:
coating it on all its surfaces with epoxy or LeTonkinois can make the paper water
-proof methinks.. and convert the cardboard into an excellent 8x8x1 case for the
bosun's locker. Butyl is an instant leak stopper. Bed-It for emergency leak repair
might be just as useful, and way easier to use, than the underwater epoxy repair kit
you ought to be cruising with...

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!
__________________________________________________ __________________________


**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."
__________________________________________________ _____________________________
*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.
__________________________________________________ _________________________
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.