Silicone is truly evil.

[Robert Lemasters]

on my Commander I used a thick weather stripping material that has a sticky side between the coamings and side decks after replacing the old screws with new larger ones.
The strip provides a great water seal, is flexable and is UV and weather proof. There is an automotive stripping for trucks and stripping for homes either will do well; although, thicker automotive may in the long run be a little better.

[CapnK]

I'm with Craig and Robert -

Been digging scraping and cursing silicone-weilding DPO's during the whole refurb of Katie Marie's brightwork. It's on the glass, and worse, even forced into the wood grain of the coamings and parts - which makes getting a good finish with varnish damned near impossible. Haven't yet primed and painted the glass in those areas - I guess I'll be finding out if I got enough of that removed when I start that phase (varnish is going on the wood right now).

Found a bad bit of core, forward port cockpit seat, where the PO had bolted a race car chair in place (he needed it for the stability it provided). That area's drying right now (if the rain will hold off), and will need fixing. At least there was no silicone there.

I had thought about using weatherstripping in place of a sealant (I like LifeCaulk), and had forgotten the idea. Thanks Robert for reminding me, as well as confirming its usefullness.

[c_amos]

FWIW,

Here is some more rant on the subject. I realized I had not mentioned my 'pull test' when I was messing with this so I wanted to include it here.

I posted this on the cruisers forum, I realize I had not posted all of this in this thread so here it is. yes, before you say it I know I am somthing of a silicone bigot...

.....it was my rant on silicone on the other thread... I am teased about being a bit over expressive on the subject. It is the result of some personal suffering based on silicone and DPO's...

Silicone is an inexpensive sealant that works well as a compression gasket (as has been mentioned in this thread already). I Like silicone for mechanical gaskets, where metal on metal (or metal on plastic) sealing where slightly (very slight) imperfections in surfaces may cause leaks. Something like waterpump (with care not to allow any globs to fall into the cooling stream for fear of causing clogs).

I am sure that the port mfg cited likes silicone, as it does not harm the ports, and allows some flex between the metal port frame, and plastic (plexi) or glass ports.

Having said that, I believe that there ought to be a law banning silicone on docks, in marina's or anywhere within 10 miles of any boat that is not designed to be scrapped before it is 10 years old....

.... Ok, maybe a LITTLE bit harsh... but just a little.

Why>?

Silicone oil (present in silicone caulk) is made up of VERY small molecules. It bleeds from the caulk into any porous or semiprous medium. While the silicone comes off easily, the oil remains.

Silicone is impervious to water, alcohol, acetone, or any petroleum-based solvent. There are some 'release agents' marketed for silicone, they are expensive and only work to remove the silicone caulk, not the oil. There are 'silicone solvents' marketed, they can wash silicone off the surface but not out of the underlying material (in my experience).

They are also pricey, so you are not going to want to use any real quantity of them.

Surfaces that have had contact with silicone not only will not hold paint, they do not prime well (primer does not bond) nor will epoxy bond to these surfaces.

Auto painters will tell you that silicone wax makes their job difficult. The silicone causes 'fish eye' which they can add an additive that increases the surface tension of the paint, but can promote chipping. THe problems with auto paint are not as serious since sanding can remove the paint which is where the silicone is carried.

Fiberglass, and wood 'wick' silicone oil deep below the surface. Sanding does not remove the oil, and can actually make the problem worse by spreading it around.

In my experience, I have painted, and had the paint lift. I then sanded and washed repeatedly with different products... to no avail.

I even went so far as to conduct 'pull tests' where I epoxied a block of scrap wood to the fiberglass I had tried to clean and prepare..... I was able to knock the block of wood off the epoxied (west, unthickened) surface with a tap from a screw driver handle.....

After several attempts to address these problems I took to using a sharp chisel to carve out the top 3/16 or so of the contaminated glass, and built up new glass to cover it...... much more work then it should have been. >

Admittedly I am a bit anal about some things, but watching paint chip off of a newly painted surface can really ruin your day. Even taking such extreme steps, I found an area the other day where I did not get it all.. and there is a small crack in the paint where it failed to bond (like you get if you paint over the waxy blush west leaves.)

Everyone does what they think is best for their own boat. I won't even use silicone on the window frames, as I might want to repaint the fiberglass that surrounds it. My hull was laid in 1964, and she is a 'good old boat', maybe that is why I think about the maintenance I do with a longer range view. I plan to keep her for some time, and want whatever I do to her to be good work, or at least something that leaves the boat better then I found it.

OBTW, I think it was last year Good Old Boat did an article on caulks and sealants and they only recommended silicone for windows, and cautioned against getting it on fiberglass and wood…. so it is not just me.

[ebb]

well said Craig!
Enjoyed yer Wrap on the subject.

BoatLife markets one of the strangest marriages of synthetic rubbers imaginable: a combination of silicone and polyurethane. Might be called LifeSeal or something.
Of course none of the tipsters in the marine media have tested this stuff for us. Does it bleed out oil? What silicone nasties have crossed over into this new goop which is supposed to be ok to use to bed in plastic windows. Partly polyurethane, can your work still be taken apart again for repair or maintenance?

Anybody have long term experience with this stuff?

A true synergistic product might be talked about, one that has the best of each and none of the bad, but I don't really hear about it. It would have to do well in the sun, and last longer than a bad memory to become popular.
Maybe it has too much to overcome. Both silicone AND polyurethane tube rubber are real trouble on the exterior of a boat.
__________________________________________________ ________________________________________________
5200
When you read boat design/woodworking forums (www.woodcentral.com) you'll find ofcourse that silicone is not mentioned - but 5200 and other glues stir up a lot of discussion. At issue is what sticks to what (SINCE NOTHING STICKS TO SILICONE NOT EVEN SILICONE - THAT PUTS IT ENTIRELY OUT OF THE PICTURE.)

And is it repairable.
Repairability of boatwork should I think be
the first consideration.


5200 sticks like a SOB (like SOB silicone) when and where you don't want it to. It looses its flex, doesn't weather particularly well, fuel destroys it, and fails as a caulk if not put together under pressure - ie it'll crack after awhile along a caulk line. Will work with mechanical fastenings. Is generally conceded that it has half the life of polysulfide. Manufactures say 10years for p.urethane, 20years for p.sulfide. But like EPA new car gas mileages, you have to divide that but 2 or 3 to get a real number. imho

[ebb]

Silicone keeps cropping up. This is a great thread to bone up on the subject - look at at craig's post here (c.amos)

One the great miscarriages of justice is that silicone is still allowed to be used on fiberglass boats. (Talking 'bout corporation ethics) But silicone removal is a problem in all spheres. It looks like the makers of the material are also coming up with the removers - which seems logical enough. I've just come off reading some DIY forums and there are folks out there who are criminally stupid. So watch it if you are trying to find information on how to clean the cabinsides where you are rebedding OR where your new windows are going.

Remove excresil by cutting it off (nope, this is not easy either) and then use a sharp pull-type scraper. Don't abrade the surface yet with sand paper. The grit will create tiny valleys where you have driven the silicon oil. Don't use any solvent like acetone. Solvents drive the oil residue into the frp laminate. Don't use a torch or heat gun on it - for the same reason. This is the last thing you want to happen.

There are silicone digesters and waterborne strippers appearing on the market. Some sound very aggressive. You might find these at an autopainting supply store. These strippers/paint preps are formulated for the trade - they may be too much for a more porus surface like fiberglass. This is our problem. I figure I can mechanically remove the rubber by cussing and scraping. But to remove the oil so that the next generation of goop will stick properly we need one that will not just drive the oil or attack the gel coat and polyester or other plastics used around the boat.

After you've successfully gotten the oil out of the gel coat then sanding prep can proceed.

Here's a silicone remover that is said to be safe on plastics and fiberglass. I have NOT used this stuff YET nor have I read any knowledgable forum-type comments on its use:

DOW CORNING OS-2 SILICONE REMOVER.
You can get a bottle from McMaster Carr for $10.23 - 10oz aerosol. (8460T3)
I have ordered some. I'll wipe the area down where silicone probably was and dab some epoxy gel on some spots where the new window gasket is going and see if it bonds. If the epoxy chips off, I'll still have a BIG problema.

Said to be an aqueous solution - said to be relatively benign is far as skin and VOCs goes. Like I say, there is no literature I can find on its practical use. Said to remove silicone oil and grease. Whether it will deep clean gelcoat fiberglass ....that is something
somebody will hopefully be kind enough to report back here to us.

Wist Marine sells polyurethanes and they have a 'debonder' for some, might not work on polyethers. They sell no remover for the polysulfides.
They also sell a couple brands of silly con but offer no deoiler for them. Their Wist Advisor doesn't admit to this very real oil problem which is obviously endemic and has been around for many Catalogs. And must be the cause of untold failures and frustration at repairing leaks.
'If we don't have it you don't need it.'

[ebb]

"Polymers and Silicones are a bodyshop's worst nightmare."

They use a 'biodegradable, environmentally safe, non-toxic' prep wash and detergent called

POLYCRACKER

Maybe auto supply, certainly auto paint store. Think it comes in iexpensive quarts. Not being a solvent, maybe it can be used with impunity on your vessel, bro.

[ebb]

FYI
Micro Care Corp 'VeriClean'

Electronics grade flammable methyl siloxane (VMS) solvent.
Removes rosins, fluxes, organic residue, ionic deposits, light grease, fingerprints. (Anybody assembling their Ham Radio kit?)
"Silicones are found in many lubricants, adhesives, conformal coatings - VeriClean removes them all...particularly effective when the coating was fully cured.
"Cleans up silicone residues from other manufacturing processes....100% votilile, cleans without need for rinsing."

"Safe on all common components, gaskets, elastomers, insulators, cables, connectors...can be used on plastics, metal, paint, glass, fiberglass....skin contact. Low odor." Can you really take a bath in it?
Datasheet avoids mention of breathing it - eyes.
Produced from quartz. (How they do that? Is it ok to ask how methyl siloxane is extracted from quartz? THOSE processes are not on the label or data sheet.)
"Degrades quickly in the atmosphere (less than 3 weeks)." THREE WEEKS!!!

"Ozone safe, including propellant - very low GWP (Global Warming Potential.)" Dow Corning. $15 aerosol, ground shipping ok.
Found it at HMC Electronics
www.hmcelectronics.com

Wouldn't surprise me at all if the stuff from McMasterCarr and this stuff is exactly the same stuff packaged in a different can, more expensive. Personally, in my opinion, Dow can't make a safe product. Not in their nature.

[ebb]

nope haven't tried it.

DSR-5, seems to be mostly aliphatic hydrocarbons and special wetting agents. They call it an "un-bonder"

You work it in where you want to remove CURED SILICONE AND 5200.
Said to be "safer than most solvents regarding skin contact and material." Non-corrisive. Non HAZ MAT.

Safe on metals, aluminum, glass, wood, cabinets, fiberglass, gelcoat, acrylic, polycarbonates, carpets ,vinyl flooring and fabrics, varnished, urethaned or painted surfaces, formica.

Removes other adhesives, contact cement, tape residue, stickers, road tar, chewing gum, enamel spray paint.

Whether it gets the oil out of the gelcoat, probably not. But maybe once you've gotten all the solid rubber away, find a solvent for silicone oil. Research, research!

[c_amos]

....find a solvent for silicone oil. Research, research!

There in lies the rub.

I am afraid that is the 'holy grail' of the sily-cone removal problem. There are lots of de-bonders out there, but NOTHIN that seems to be a real solvent.

What I understand though is that the only real solvent for silicone is silicone....

[ebb]

Stuff we need may turn out to be a super detergent, or a super emulsifier*, or something ghastly that denatures the soaked in (organic) oil. No solvent seems to melt the stuff. Can't be any kind of a coating or primer we now have, that's the rub.

On those cockpit sidedecks I ended up removing the gelcoat!!!!!
The problem is we are a shrinking niche market for a silicone oil remover.

Wonder if butyl makes a good sticky seal on contaminated gelcoat. In theory we wouldn't usually need an adhesive bond for watertight fasteners......
__________________________________________________ __________________________________________________ __
* Polygone is a silicone emulsifier (digestor) used in the aircraft industry. So strong you don't use it on copper, aluminum, galvanized or plastics. They have a formula that even breaks down polysulfide.
On a "finishers" site where a thread is discussing prep and how to clean off silicone, one guy is saying that silicone contamination is in parts per billion - even on stainless steel you can not remove all of it - and in parts per billion, the molecules left on stainless will still screw up the coating you want to put on.

In terms of contaminaion we can place Silicone on the same HALF LIFE scale as Plutonium 239 - 24,000 years!

[c_amos]

....I ended up removing the gelcoat!!!!!
The problem is we are a shrinking niche market for a silicone oil remover....

As I have complained about since I did it, I removed the gelcoat and even chiseled out some of the underlying fiberglass.... and I still have some localized paint failures where I did not get all of the dreaded stuff.

I have a couple places on the sidedecks where the jib track was bedded with silicone that were stripped, over drilled, filled and double primed... and they have failed. I really, truly, passionately hate silicone.

Wonder if butyl makes a good sticky seal on contaminated gelcoat. In theory we wouldn't usually need an adhesive bond for watertight fasteners......

Yes, I hope so. I would think it would work well, since you are putting it in compression and not relying on adhesion to keep it in place.

[Hull376]

Lots of opinions in this thread. How bout any "results?" I've got to re-bed my dead lights which were last bedded with sillycone. A local RV supply store has sticky butyl rubber tape (1"x3/16"x20ft) on sale. And it is white. So any experience from using this tape on deadlights? I want to avoid using anything out of a tube. The last time I did the job single handed, things slipped and slid around so much before the screws on the frames could be tightened that most of the tube contents were on my body. I think I still have those micro molecules of sillycone oil permanently infused into all 5-7 layers of my skin. Maybe also why I can't seem to hold on to a golf club anymore. But I've noticed that paint clean-up on my hands is very fast. If no experience with tape butyl since these posts, then I guess I'll be a sticky butyl rubber tape guinea pig.

[mbd]

Kent,

No first-hand experience, but I am looking forward to trying it out when I rebed my stanchions.

There is a great website with lots of projects and excellent pics: Compass Marine Project Articles

He uses butyl tape to bed some new portlights here: Installing New Found Metals Stainless Portlights

[ebb]

We certainly done a bunch of rantin-n-aravin about silicone here.
It has its place in the engine room.
There is a hybrid by BoatLife called LifeSeal which by other manufacturers is well thought of. It's not new, been around for 20 years. LifeSeal is a silicone/urethane mix. Supposed to have the best of each and none of the bad.

I've used it on the boat, but it is untested. Its ability to stay attached to surfaces and, most of all, to stay flexible for 20 years in the tropics I have yet to witness.
I check the forums every now and again but most can't yet make the distinction between LifeSeal hybrid and BoatLife LifeCaulk polysulfide. It is Boat Life's fault in keeping the confusion going.
Professionals use Bostick products who have customed the hybrid for specific uses. Like one hybrid for caulking teak and synthetic decks and another that resists squeezeout for bedding stanchion bases and portlights.
[Adding to the confusion is exampled by BoatLife selling a 'marine quality silicone sealant' under their own label. Doubt there are cautions about its use around a boat on the tube. I think this irresponsible. And is a major reason I steer away from their products.]
Would think that Sika and 3M have their versions.

So there is a 'silicone' product that could be used if you want to pay for it.

Imco most of our aps can't really use a wet caulk successfully. Bostick's hybrid silthane for mounting stuff has body built into it, forget the term they use. LifeSeal has only the one tube, I believe. If you don't have a thick hard-to-squeeze goop there's no gasket quality. If you got metal to fiberglass you going to leak even tho you put $5 of rubber there.


SO, butyl IS THE WAY TO GO.
If you use butyl tape you don't have a mess.
If you have a difficult surface you can augment with tube butyl. IT's very sticky, so I believe you can get as good a seal as with the adhesives: polysulfide and polyurethane. You are just not gluing your fitting in forever.
And maybe having it leak anyway.
You have to learn how to use butyl. If you have something like a portlight that always requires rebedding then use butyl bedding not adhesive. Most cruisers use butyl I believe for portlight frames. Haven't heard any grousing about it - but then most forums are not set up for follow-through on a subject.

Butyl will always stay soft (pliable) and sticky. Polysulfide can get hard and start cracking in a couple years, depends where you are located.
I don't doubt that butyl can give up the ghost but it's a piece of cake to take the fitting or whatever apart and rebed it. You know it's something you can do, not something you want to avoid.

That's my take on Butyl. The tape and tube are inexpensive. I'll bet their storage life is 10 times longer than tube polysulfide. Means we can have it in the bosun's locker, always available.


I have a Marelon seacock that's going in on 1/8" b.tape. I'll use tube b. on the thruhull flange and in the bolt holes. Underwater, I know, but if it leaks I can redo it OR clean it off with Stoddard solvent and zapp it with polysulfide.

I'll have lexan windows bolted on over butyl tape. It bends nicely around curves. I can see the method (simplified) as stick on the tape, locate the fastening holes, put the fixture in place, poke the fasteners thru with a bit of wet butyl. With a seethru material like lexan dry spots will be noticed. I'm thinking that a dry surface could be primed by pre-smearing wet butyl on it to help get 100% contact? That's an idea for now.

[Hull376]

Mike,

Thanks for the tips on the site. I guess it doesn't take a lot of work to clean up or re-do a butyl tape installation if it doesn't work out. Mineral spirits and its gone, looks like to me. I'll let you know if I do it, and how it turns out.

And ebb, you comments are very much appreciated. Your rational is sound. I'll give it a go.