Sealant curing

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Graham_Wright

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I fitted a deck gland sealed with silicone sealant. Needing to remove it a few days later (poor planning) I discovered the sealant was only cured near the perimeter. I assume it needs air to cure. Is this right? It would explain why the cartridge nozzle is only blocked a short distance from the end.

Will it eventually cure or is there an alternative sealant (possibly two part?) that will self cure?

Then I guess it would be solid in the cartridge from the day of manufacture.

Apologies for the naïvety.
 
One-part silicone sealant cures by gradually absorbing moisture from the atmosphere. You can get 2-part silicone sealant, but the 1-part stuff should be OK for ordinary boat use above the waterline, and is much easier to remove if (as you've found) it becomes necessary.
 
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Instead of silicone use Sikaflex or CT1 in a marine environment. They are adhesives as well as sealants. Silicone is just about OK in your bathroom but not much else, it does not adhere well to anything.
Most sealants cure from the outside in and it does take some time. CT1 even cures and sticks underwater - great stuff.
 
Silicone is cured by reaction with ambient moisture.I usually allow the sealant to go off and apply a fresh thin layer just before assembly.This way there'll always be a (cured) thickness of sealant that acts as a gasket .
 
SAMYL said:
Instead of silicone use Sikaflex or CT1 in a marine environment. They are adhesives as well as sealants. Silicone is just about OK in your bathroom but not much else, it does not adhere well to anything.
Most sealants cure from the outside in and it does take some time. CT1 even cures and sticks underwater - great stuff.
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The one I used was Arbosil 1081 claimed applications including glass to glass joints. I've have used Sikaflex in the past but it is perhaps too adhesive for this use.. I will need to remove this gland when unstepping the mast.
 
Silicone has no place on a boat ban it and use the correct sealant for the job. I wont let silicon sealant on my boat, it never does any job better than the correct material....... unless you count making a mess :)

Tom
 
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LittleShip said:
Silicone has no place on a boat ban it and use the correct sealant for the job. I wont let silicon sealand on my boat, it never does any job better than the correct material....... unless you count making a mess :)

Tom
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Statements like that are not very helpful. They could be born of wisdom, experience, technical knowledge or as a result of shares in the competitors company.

Equally, they could be born of prejudice.

Either way, it would be helpful to have them justified.
 
Graham_Wright said:
Statements like that are not very helpful. They could be born of wisdom, experience, technical knowledge or as a result of shares in the competitors company.

Equally, they could be born of prejudice.

Either way, it would be helpful to have them justified.
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I was going to post a reply to this as well but then decided not to.But here goes anyway.In my experience a good silicone sealant can be very good.My forehatch was fitted with it and never leaked.My Nasa skin fitting is also sealed with silicone as per manufacturers specifictions.It's all down to technique and when properly done it's actually less messy than Sikaflex.
 
sealant

well i to think that silicone should not be used on a boat,i have only used it twice many many years ago and it failed both times.i dont think i have ever read any claim by a silicone manufacturer that it is good for marine use,sickaflex is great but,it is very strong and will not be easy to remove,for glands and deck fittings that need to be removed from time to time there is a sealant i think its called arbour its a butyl putty based sealant and its never let me down it never goes off and i have even taken fittings off and put them back using the same sealant,in short my advice DO NOT USE SILICONE on a boat(sorry if thats not very helpfull) Kieron
 
I use silicone all the time for sealing above the waterline under bolt/screw heads and the like. It's cheap and effective. Below the waterline I use Sikaflex but as it's expensive, I try to 'group' jobs together so I can use a whole cartridge. Otherwise you are paying for stuff to go off in the tube. Check on shelf life/sell by date as well when buying.
 
Silicone sealant is fine for use about the waterline, and many boatbuilders and yards use it all the time. It's clean, cheap and effective.

For small sealing jobs below the waterline, rather than using Sikaflex, I keep a little tube of Life Calk on the boat.
 
Kindred Spirit had clear silicone everywhere, applied by the previous owner. Most of it was leaking. The very first job I did on board was replacing the access hatch in the cockpit sole; not then knowing any better, I did it with silicone. It too is now leaking, and refitting it properly with Sikaflex 291 is on my list for this winter.

I wouldn't presume to tell others what to do, but I don't use silicone on board.

Sikaflex 291 is not particularly cheap, and I suspect there are non-marine products that would do just as well. But I know where I am with Sika, and the cost of what you use on any given job (a couple of quid at most, for something big needing 1/4 of a tube) is not worth my time to re-do the job if some other goop turns out not to work.

I find a piece of kitchen foil over the nipple on the cartridge, with an old bunged-up nozzle screwed down over it, keeps it soft for a reasonable time.

Various people talk about the vicelike grip of Sika that will lock your parts together for all eternity. I just assume they've been using Sikaflex 292 instead of 291 - the latter is a sealant with some adhesive properties, the former is, according to the manufacturer, a structural adhesive and a viable replacement for rivets, screws or welds. That's probably not what you want.

Pete
 
Graham_Wright said:
Statements like that are not very helpful. They could be born of wisdom, experience, technical knowledge or as a result of shares in the competitors company.

Equally, they could be born of prejudice.

Either way, it would be helpful to have them justified.
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it never does any job better than the correct material

I would say that is a qualification IMHO ? As for being helpful... well if somebody reads this and uses the better properly designed for the job material that would be helpful.

If however you want a list of what product to use then searching the web for application data is available to all.

My statement is based on experiance..... Ok !

As this thread has shown i'm not alone in my feelings about Silicone and using it in the marine environment.

Tom
 
Dont use silicon;

IMG_0929.jpg


Seemed like a good idea at the time.
 
silicone

the worst thing about silicone is that it will not stick to itself once its gone off,so if it doesnt work the first time you are ------.not only wont it stick to itself nothing else will stick to it,quite worrying on a boat,if you clean the old surfaces perfectly then you may be ok but that is almost imposible to do.that is why i will never use it again.i have checked up on this since my first post ,i did think i was correct but it never hurts to check.if it has worked for you then best of luck in the future but if you are still wondering what to use then i would give silicone a miss.Kieron
 
Vara said:
Dont use silicon;
Seemed like a good idea at the time.
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Seem to recall when you posted that before, some time ago, that it was silicone sealant in a plastic box in a damp location, and that someone mentioned that the acetic acid produced during curing could corrode the wires.
 
pvb said:
Seem to recall when you posted that before, some time ago, that it was silicone sealant in a plastic box in a damp location, and that someone mentioned that the acetic acid produced during curing could corrode the wires.
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The location (inside a binnacle) was as dry as anywhere on a boat is. As far as I could see all the damage was done by the sealant in its curing process.
 
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