Mixing Butyl and silicone

tom52

tom52

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I am fitting new glass into an aluminium frame. I plan to bed the glass and set in centrally into the U shaped extrusions on all four sides using butyl tape and then finish the sealing with silicone.

Is this wise ? Will silicone stick/seal to butyl.

Any advice suggestions gratefully received.
 
tom52 said:
I am fitting new glass into an aluminium frame. I plan to bed the glass and set in centrally into the U shaped extrusions on all four sides using butyl tape and then finish the sealing with silicone.

Is this wise ? Will silicone stick/seal to butyl.

Any advice suggestions gratefully received.
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Personally, I wouldn't use silicone. In fact i wouldn't use silicone on anything - i hate the stuff. If its for external sealing the defininately not silicone. There are plenty of great products on the market for this now. My current personal favorite is now CT1 for just about everything. Sika also do a good sealant with UV protection.
 
tom52 said:
I am fitting new glass into an aluminium frame. I plan to bed the glass and set in centrally into the U shaped extrusions on all four sides using butyl tape and then finish the sealing with silicone.

Is this wise ? Will silicone stick/seal to butyl.

Any advice suggestions gratefully received.
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Silicon is not for boat use.
If you with silicon refer to different sealants like sikaflex it's different matter.

We installed new aluminium widow frames with new windows 5 years ago.
The recommendation from the window maker was to bed with butyl tape, still no leaks.
The only problem is that we get some gray dirt traces under the window - the cure is to use a little string of sealant around the edges of the window frame.
Have not tested this bur cant see any problems with that.
 
Maybe it's different in Norway, Vic?

Otherwise +1 with knuterikt.
Butyl is excellent stuff, with the qualification he mentioned.
Silicone sealant is the spawn of the devil and beloved mainly by botchers.
Silicon I have no strong feelings about one way or the other. According to Wiki it's the eighth most common element in the Universe, although judging by the excesses of my boat's previous owner, silicone is catching up fast :ambivalence:

P.S. Any smears of butyl on acrylic/perspex can be safely, if a little laboriously, removed with olive oil on a rag. (No doubt many other oils are OK, too, but I know olive oil to be safe -- and always aboard.)
 
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Silicone is fine for a lot of boaty jobs. It is actually specified for a number of underwater applications.

The cheaper stuff smells of vinegar and is available down the pound shop. It is probably worth doing a bit of research before buying for marine use:

http://www.abbuildingproducts.co.uk/marine-silicone-sealant-pr-76.php

Having said that I would not use it for windows and would shy away from mixing any two solutions. The butyl tape seems to be highly recommended for the job.
 
All above is good but if you doing use any silicone only use neutral cure low modulus constructional used for glueing fish tanks,however the jump on board eastern manufactureres will put write anything on a tube .
 
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+1 I would definitely keep away from silicone. Try and look for something like http://www.bostik.com.sg/Products/Transportation/Marine/Simson_MSR_Fast_Tack
If you read the specs on this there seems to be very little difference between the bedding compound, construction adhesive and the deck caulking, only the price I would imagine! I'm no chemist so I could not advise and probably someone will come along and give us all a lesson.
 
VicS said:
Not entirely true

it is a hard, brittle "metalloid" element but finds a small but important use in the microelectronics so popular these days.
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Sorry for the confusion
Name: Silicon
Symbol: Si
Atomic Number: 14

Have different name in Norwegian - we call it "Silisium"

Fun with languages and almost similar words.
 
Silicon is absolutely necessary on a boat.
Without it most of the electronics would not work. (diodes, transistors)

An organic derivative of silicon, silicone has some uses, but there are mostly better products. An exception is some paints containing silicone, some quite good in marine service.
 
MM5AHO said:
Silicon is absolutely necessary on a boat.
Without it most of the electronics would not work. (diodes, transistors)

An organic derivative of silicon, silicone has some uses, but there are mostly better products. An exception is some paints containing silicone, some quite good in marine service.
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Fair point but I think we are talking different horses for different courses here.
 
If you want to add something a bit more squeezy than the butyl tape, you could use Abormast BR. It is basically liquid butyl.

The pro that put my aluminium framed windows back in used it very successfully. It is soft enough to squidge into the irregular voids and conform. It has all the benefits of butyl when it comes to sealing.
Clean up with white spirit and paper towels.

There is no place for bathroom sealant on a boat.... not even in the heads!!! If it is possible to do it with silicone, CT1 will do it WAY better!
 
Alpha22 said:
There is no place for bathroom sealant on a boat.... not even in the heads!!! If it is possible to do it with silicone, CT1 will do it WAY better!
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According to the data sheet CT1 is modified silicone (MS).

Thanks everyone for the relevant replies. Interesting trenchant views on silicone being unsuitable for boats. Not all silicone is bathroom sealant.

Lots of reputable manufacturers like Dow Corning produce Marine Silicone.
 
I too am reglazing an aluminium window. And have been trying to decide what to seal glass into frame. The stuff I took out was just a perished rubber strip, no other sealant. It was very easy to clean the frame and presumably had been in since new forty years ago. I contacted Seals Direct (very helpful) who advised using rubber again but with silicone sealant in the bottom of the rubber and the bottom of the aluminium channel (NOT Sika). Apparently silicone sticks to glass better than Sika type stuff.
I'm not prejudiced against silicone and have used it quite a lot on boats in the past before I learnt of the existence of Sikaflex, PU40 and CT1.
My point is that seals direct know what they are about so I will take their advice.
 
Amendment to above. I reassembled my window this afternoon using PU40 because I already had some and wanted to get it done. Messy job and should have worn gloves but quite pleased with the result. I don't envy the person that has to do it next because the sealant will be much harder to remove than the original rubber moulding.
ghostlymoron said:
I too am reglazing an aluminium window. And have been trying to decide what to seal glass into frame. The stuff I took out was just a perished rubber strip, no other sealant. It was very easy to clean the frame and presumably had been in since new forty years ago. I contacted Seals Direct (very helpful) who advised using rubber again but with silicone sealant in the bottom of the rubber and the bottom of the aluminium channel (NOT Sika). Apparently silicone sticks to glass better than Sika type stuff.
I'm not prejudiced against silicone and have used it quite a lot on boats in the past before I learnt of the existence of Sikaflex, PU40 and CT1.
My point is that seals direct know what they are about so I will take their advice.
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tom52 said:
According to the data sheet CT1 is modified silicone (MS).

Thanks everyone for the relevant replies. Interesting trenchant views on silicone being unsuitable for boats. Not all silicone is bathroom sealant.

Lots of reputable manufacturers like Dow Corning produce Marine Silicone.
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Must admit that the silicone I have found on my boats looks like bathroom silicone and it has obviously not worked well since I had to re bed the HW (The silicone had a non impressive bond with the surface).
 
Silicone sealant contains acetic acid(vinegar smell) & will corrode aluminum.
Butyl tape is what holds your car windscreen in place,without any other mechanical fasteners in many cases. Why would it not hold & seal a marine window just as well ?
Silicone sealant is a gasket material,meant to be clamped between two hard objects by mechanical fasteners. It is a poor caulking material,especially outdoors in sunlight.It does not stick well to many substrates,& even when it appears to,it will soon peel away.
If you must use a cartridge caulking material,use a marine polysulfide based product such as Sika,3M 4200,etc.
Then there is 3M 5200-if you want to plank a boat & then remove the nails.It sticks so well to just about everything,you will destroy the substrate trying to get it apart.Not recommended by me for much around a boat.

Cheers / Len
 
Len Ingalls said:
Silicone sealant contains acetic acid(vinegar smell) & will corrode aluminum.
Butyl tape is what holds your car windscreen in place,without any other mechanical fasteners in many cases. Why would it not hold & seal a marine window just as well ?
Silicone sealant is a gasket material,meant to be clamped between two hard objects by mechanical fasteners. It is a poor caulking material,especially outdoors in sunlight.It does not stick well to many substrates,& even when it appears to,it will soon peel away.
If you must use a cartridge caulking material,use a marine polysulfide based product such as Sika,3M 4200,etc.
Then there is 3M 5200-if you want to plank a boat & then remove the nails.It sticks so well to just about everything,you will destroy the substrate trying to get it apart.Not recommended by me for much around a boat.

Cheers / Len
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constructional low mod silicone, neutral cure doesn’t smell of vinegar-- nothing like cheap acetic acid silicone . The type with no fungicide is used to glue glass fish tanks.

polysulphide is good
 
In general I use no silicone on my boat. It doesn't last and anywhere it touches fiberglass, wood or any other permeable material you will have trouble forever getting anything to stick, even more silicone. Butyl tape for bedding anything to the hull or deck.

The ONE exception, if you are glazing new glass or plexiglass into a hatch or port frame the experts do recommend high grade marine modified silicone adhesive/sealant for that job. Here's a link to the best in the business (at least on this side of the pond) and their recommendations.

http://www.selectplastics.com/index.php/tonys-blog/2-blogs/tonyd/12-sealants

I used the Dow 795. More readily available to me and no need for a separate primer.

http://www.dowcorning.com/applications/search/default.aspx?R=264EN

Be aware, this stuff is MESSY!!!! It will stick to anything and everything within a 10' radius of the tube. Be careful to tape off all the edges and surrounds of whatever you're working on as coming back to clean and scrape the overflow is tedious to say the least.
 
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