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Author Topic:   Silicone Sealant

jimh posted 07-10-2009 04:00 PM ET (US)
What is the difference between:
3M Marine Grade Clear Silicone Sealant, Mildew Resistant, 10-oz = $25 at West Marine
--and--
DAP Dow Corning Clear Silicone Sealant, Mildew Resistant, 10-oz = $5 at my hardware store,
other than the $20 difference in price?

3M
DAP
number9 posted 07-10-2009 05:20 PM ET (US)
FYI, 3M $17.89 at wholesalemarine.com.
As for difference in prices? Only difference I picked up on reading their tech. data was 3M 3 year shelf life versus DAP 1 year.
Blackduck posted 07-10-2009 05:21 PM ET (US)
I'm sure there is some difference in their formulas, well maybe. They sure smell the same, dry the same, and feel the same when they are dry. I've noticed that in time, the clear silicone I use in exterior construction yellows. Maybe a "marine grade" will not.
For what most of us would use silicone sealant for, bedding screws, ect, above the waterline, I think regular "builders grade silicone" is just fine.
TransAm posted 07-10-2009 08:09 PM ET (US)
Probably has some extra secret ingredient in it. Like the Yamalube West Marine sells. It too must have some extra secret additive in it that my local marina shop does not.
West Marine Yamalube=$47.99/gallon
Rhode River Marina=$23.16/gallon
ConB posted 07-10-2009 08:18 PM ET (US)
I have wondered if all silicone sealant was the same.
I owned a 1964 Pearson Triton sailboat. The bronze through hull fittings were bedded in what appeared to be silicone sealant.
I do not know if the factory or a previous owner choose the silicone to bed the through hulls.
The Triton was 40 years old when I sold it and there never was a problem with any of the though hull fittings.
The silicone would have been my last choice for bedding bellow the water line, but there you go.
Con
TransAm posted 07-10-2009 08:31 PM ET (US)
Silicone is often the preferred choice when bedding in water related applications is called for. Wanna guess what joints in glass aquariums are sealed with?
R T M posted 07-10-2009 08:35 PM ET (US)
Roof cement? hey it holds back water, who cares. Any kind of silcone sealent is a cruel joke.
rich/Binkie
jimh posted 07-10-2009 09:36 PM ET (US)
It turns out at my local hardware store the DAP Silicone Sealant is $6.49, but that is still a lot cheaper--and much more convenient to get--than WEST Marine's 3M Marine Grade Silicone Sealant. I did not plan ahead very well, so I could not mail-order the 3M Silicone Sealant and pay $7 shipping.
number9 posted 07-11-2009 02:55 AM ET (US)
Neither the 3M or DAP mentioned are recommended using below the water line.
DAP® Silicone Plus™ Premium Silicone Rubber Kitchen & Bath Sealant 08781 might be a good choice for the marine environment?
aussiejake posted 07-11-2009 07:56 AM ET (US)
Be careful using standard silicons around metal / alloy areas of the boat as non recommended cheap silicons contain a higher acid content and the acid will corrode the metal parts.
I sealed the engine mount bolts with a tube of hardware silicon I had in the shed and after a few months I noticed a powder around the bolts and engine bracket....the alloy was corroding.
I will get some more info from an aircraft engineer who warned me of the issues and I will post more specific details.
cheers,
Jake.
number9 posted 07-11-2009 02:53 PM ET (US)
Even the high dollar Dow Corning silicone commonly used in the aircraft industry releases acetic acid during cure.
From 3M: "Do not use with electronic circuitry. Acetic acid liberated during cure may corrode electronic circuitry."
From DAP: "Not recommended for use on brass, copper, magnesium, zinc, iron, galvanized metals or other surfaces
prone to attack by weak acids."
From Dow Corning: "Dow Corning 736 Heat Resistant
Sealant is not recommended: On or near sensitive metals such
as copper, brass, zinc, carbon steel, galvanized iron or magnesium; these metals may be corroded, especially in confined cure conditions, due to the acetic acid released during the cure."
Even 3M 4200 & 5300 have their limitations: "Fast Cure 4200 is not recommended for use as a teak deck seam sealer. Extended exposure to chemicals (teak cleaners, oxalic acid, gasoline, strong solvents and other harsh chemicals) may cause
permanent softening of the sealant.
Many of the hull cleaners on the market must have the potential to soften the 4200 & 5200. It would be interesting to see some testing done.
HAPPYJIM posted 07-11-2009 08:15 PM ET (US)
Urethane sealants are not corrosive to metals. Silicone is.
Jefecinco posted 07-12-2009 10:10 AM ET (US)
Bite the bullet. Buy the good stuff and sleep well. A Whaler deserves the best.
Butch
jimh posted 07-12-2009 10:12 AM ET (US)
Too late, Butch. I already bought the Dow Corning Silicone. Check back in a year and I will let you know if the hatch leaked that I used the silicone to seal.
PeteB88 posted 07-12-2009 07:55 PM ET (US)
I think Dow Corning invented the stuff - called RTV, Room Temperature Vulcanizing. It's on the web - all kinds of info.
15ft90hp posted 07-13-2009 09:28 AM ET (US)
I think this post is silly, cheap silicone sealant and kitchen & bath sealant to use on your what, $5000.00 to $40,000.00 Boston Whaler. Come on guys, dish out the clams for the 3M good stuff, it's only a few bucks more for your Large investment!
tom976 posted 07-20-2009 10:39 AM ET (US)
Did you ever check your local home depot for 3m 5200???
They sell it too (mine does) Its only 13 or 14 bucks for a standard size tube. The local marine ripoff center wanted 24.99 for it. Sad. No wonder they went out of business. (Boaters World)
Tom
L H G posted 07-20-2009 01:18 PM ET (US)
I think the best sealants for use in a boat are the "BOATLIFE" products "Life Seal" and "Life Caulk". Life Seal is a polyurethane/silicone adhesive sealant, in clear or white, and the Life Caulk is Thiokol based Polysulfide sealant (the stinky stuff). Use either of these and forget it. They last and last, and for wet areas also.
gorji posted 07-20-2009 06:26 PM ET (US)
Related to this topic is what to do when you open the tube. Curing will start according to the 5200 label. Will the same thing happen with BoatLife? Anyone have any tricks to use a fresh tube of 5200 or similar sealant and not have to lose the rest of the contents to curing?
Thanks
Chuck Tribolet posted 07-20-2009 09:00 PM ET (US)
The Boat Life Life Caulk will keep reasonable well if you
keep it in a freezer grade ziplock in the fridge. Note that
it will stink up the fridge. I keep mine in the fridge in
the bar.

Chuck

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Author	Topic: Silicone Sealant
jimh	posted 07-10-2009 04:00 PM ET (US) What is the difference between: 3M Marine Grade Clear Silicone Sealant, Mildew Resistant, 10-oz = $25 at West Marine --and-- DAP Dow Corning Clear Silicone Sealant, Mildew Resistant, 10-oz = $5 at my hardware store, other than the $20 difference in price? 3M DAP
number9	posted 07-10-2009 05:20 PM ET (US) FYI, 3M $17.89 at wholesalemarine.com. As for difference in prices? Only difference I picked up on reading their tech. data was 3M 3 year shelf life versus DAP 1 year.
Blackduck	posted 07-10-2009 05:21 PM ET (US) I'm sure there is some difference in their formulas, well maybe. They sure smell the same, dry the same, and feel the same when they are dry. I've noticed that in time, the clear silicone I use in exterior construction yellows. Maybe a "marine grade" will not. For what most of us would use silicone sealant for, bedding screws, ect, above the waterline, I think regular "builders grade silicone" is just fine.
TransAm	posted 07-10-2009 08:09 PM ET (US) Probably has some extra secret ingredient in it. Like the Yamalube West Marine sells. It too must have some extra secret additive in it that my local marina shop does not. West Marine Yamalube=$47.99/gallon Rhode River Marina=$23.16/gallon
ConB	posted 07-10-2009 08:18 PM ET (US) I have wondered if all silicone sealant was the same. I owned a 1964 Pearson Triton sailboat. The bronze through hull fittings were bedded in what appeared to be silicone sealant. I do not know if the factory or a previous owner choose the silicone to bed the through hulls. The Triton was 40 years old when I sold it and there never was a problem with any of the though hull fittings. The silicone would have been my last choice for bedding bellow the water line, but there you go. Con
TransAm	posted 07-10-2009 08:31 PM ET (US) Silicone is often the preferred choice when bedding in water related applications is called for. Wanna guess what joints in glass aquariums are sealed with?
R T M	posted 07-10-2009 08:35 PM ET (US) Roof cement? hey it holds back water, who cares. Any kind of silcone sealent is a cruel joke. rich/Binkie
jimh	posted 07-10-2009 09:36 PM ET (US) It turns out at my local hardware store the DAP Silicone Sealant is $6.49, but that is still a lot cheaper--and much more convenient to get--than WEST Marine's 3M Marine Grade Silicone Sealant. I did not plan ahead very well, so I could not mail-order the 3M Silicone Sealant and pay $7 shipping.
number9	posted 07-11-2009 02:55 AM ET (US) Neither the 3M or DAP mentioned are recommended using below the water line. DAP® Silicone Plus™ Premium Silicone Rubber Kitchen & Bath Sealant 08781 might be a good choice for the marine environment?
aussiejake	posted 07-11-2009 07:56 AM ET (US) Be careful using standard silicons around metal / alloy areas of the boat as non recommended cheap silicons contain a higher acid content and the acid will corrode the metal parts. I sealed the engine mount bolts with a tube of hardware silicon I had in the shed and after a few months I noticed a powder around the bolts and engine bracket....the alloy was corroding. I will get some more info from an aircraft engineer who warned me of the issues and I will post more specific details. cheers, Jake.
number9	posted 07-11-2009 02:53 PM ET (US) Even the high dollar Dow Corning silicone commonly used in the aircraft industry releases acetic acid during cure. From 3M: "Do not use with electronic circuitry. Acetic acid liberated during cure may corrode electronic circuitry." From DAP: "Not recommended for use on brass, copper, magnesium, zinc, iron, galvanized metals or other surfaces prone to attack by weak acids." From Dow Corning: "Dow Corning 736 Heat Resistant Sealant is not recommended: On or near sensitive metals such as copper, brass, zinc, carbon steel, galvanized iron or magnesium; these metals may be corroded, especially in confined cure conditions, due to the acetic acid released during the cure." Even 3M 4200 & 5300 have their limitations: "Fast Cure 4200 is not recommended for use as a teak deck seam sealer. Extended exposure to chemicals (teak cleaners, oxalic acid, gasoline, strong solvents and other harsh chemicals) may cause permanent softening of the sealant. Many of the hull cleaners on the market must have the potential to soften the 4200 & 5200. It would be interesting to see some testing done.
HAPPYJIM	posted 07-11-2009 08:15 PM ET (US) Urethane sealants are not corrosive to metals. Silicone is.
Jefecinco	posted 07-12-2009 10:10 AM ET (US) Bite the bullet. Buy the good stuff and sleep well. A Whaler deserves the best. Butch
jimh	posted 07-12-2009 10:12 AM ET (US) Too late, Butch. I already bought the Dow Corning Silicone. Check back in a year and I will let you know if the hatch leaked that I used the silicone to seal.
PeteB88	posted 07-12-2009 07:55 PM ET (US) I think Dow Corning invented the stuff - called RTV, Room Temperature Vulcanizing. It's on the web - all kinds of info.
15ft90hp	posted 07-13-2009 09:28 AM ET (US) I think this post is silly, cheap silicone sealant and kitchen & bath sealant to use on your what, $5000.00 to $40,000.00 Boston Whaler. Come on guys, dish out the clams for the 3M good stuff, it's only a few bucks more for your Large investment!
tom976	posted 07-20-2009 10:39 AM ET (US) Did you ever check your local home depot for 3m 5200??? They sell it too (mine does) Its only 13 or 14 bucks for a standard size tube. The local marine ripoff center wanted 24.99 for it. Sad. No wonder they went out of business. (Boaters World) Tom
L H G	posted 07-20-2009 01:18 PM ET (US) I think the best sealants for use in a boat are the "BOATLIFE" products "Life Seal" and "Life Caulk". Life Seal is a polyurethane/silicone adhesive sealant, in clear or white, and the Life Caulk is Thiokol based Polysulfide sealant (the stinky stuff). Use either of these and forget it. They last and last, and for wet areas also.
gorji	posted 07-20-2009 06:26 PM ET (US) Related to this topic is what to do when you open the tube. Curing will start according to the 5200 label. Will the same thing happen with BoatLife? Anyone have any tricks to use a fresh tube of 5200 or similar sealant and not have to lose the rest of the contents to curing? Thanks
Chuck Tribolet	posted 07-20-2009 09:00 PM ET (US) The Boat Life Life Caulk will keep reasonable well if you keep it in a freezer grade ziplock in the fridge. Note that it will stink up the fridge. I keep mine in the fridge in the bar. Chuck