"Window Tape" That Passes Water - What on Earth Is it For?

[alan_fincher]

I have just got a complete surprise having bought a roll of this stuff.

 

 

As it says it has self adhesive tape on one surface.

 

I assumed this stuff could either be used to mount windows or portholes on, or as the sealing edge around opening windows and hatches.

 

So I am more than a bit surprised to find that the material used is of a foam construction, and soaks up water like a sponge, such that when you squeeze it, it squirts out again.

 

I'm feeling pretty miffed, not just because Midland Chandlers only sell it by the roll at £19.50, but also because my attempted use of it simply had water pissing though it.

 

So if the tape is not actually waterproof, what possible application does it have to boat windows?

To be fair the listing doesn't actually say it is waterproof, but before I raise it with the chandlers, can anybody suggest what a non waterproof tape might be sold for?

[nicknorman]

That sort of tape should be "closed cell" tape - ie the little bubbles aren't connected to each other so it is a foam, but doesn't pass water through it. Perhaps MC ordered the wrong tape, and got open cell instead? Does it say anything on the tape/packaging about being open cell or closed cell?

[Jerra]

It looks like the stuff that was used a few decades ago for draught proofing windows and doors.

[Sea Dog]

Oh no! I bought mine off ebay for about 1/10th that cost. It was perfect for the job too: looks good, stuck really well, and it's closed cell so doesn't absorb water. As the icing on the cake, within a few days of replacing the stuff on my boat, a fellow boater I was sharing a lock flight with with asked if they were new windows!

[Rickent]

I bought butyl window tape from mc . I know that won't pass water.

[alan_fincher]

Does it say anything on the tape/packaging about being open cell or closed cell?

 

No it is packed in a transparent bag with nothing printed on it whatsoever.

 

I'm aware of the difference between open cell and closed cell, but if tape were closed cell, and you wetted it, how much water would you expect it to expel if you then squeezed it? I would assume only small amounts, because it could only get into holes that were on the surface but no further in. This is soaking up enough water that if you press you thumb into it significant amounts are squirted out. Could that happen if it were closed cell?

I bought butyl window tape from mc . I know that won't pass water.

 

I think that is the one like a type of thick putty, but on a roll? Fine for bedding windows down on - in fact I have regularly used a similar thing called "Glasticord", and it is excellen.

 

However I am after something to use as a seal in a window that opens. That is not a case where you can use the butyl one!

[dmr]

Is that Butyl rubber tape? I got some off ebay and used it to seal the little port-holes in the Pigeon boxes. It was (and still is) 100% waterproof though in future I think making neoprene gaskets is the way to go. So if its not butyl rubber what on earth have they sold you?????

 

There is an old (rather silly) practical joke where you give people washing up sponges made out of closed cell foam, is this the opposite??????

 

...............Dave

[alan_fincher]

It looks like the stuff that was used a few decades ago for draught proofing windows and doors.

 

Not really as it is only about 3mm thick - the stuff I think you are talking about was usually at least twice that, and of a much more "open" construction.

 

Until you examine it closely, you would think this is a solid neoprene (or similar) strip. Only close examination reveals it to be a foam with very small holes.

[nicknorman]

 

No it is packed in a transparent bag with nothing printed on it whatsoever.

 

I'm aware of the difference between open cell and closed cell, but if tape were closed cell, and you wetted it, how much water would you expect it to expel if you then squeezed it? I would assume only small amounts, because it could only get into holes that were on the surface but no further in. This is soaking up enough water that if you press you thumb into it significant amounts are squirted out. Could that happen if it were closed cell?

 

Well I'm no expert but the whole point of closed cell is as you say - the water shouldn't be able to get beyond the surface. You would expect it to barely soak up any water at all. Sounds to me like MC have bought in the wrong stuff.

[Rickent]

Yes Alan its like putty on a roll which never sets. Should sort my windows out a treat but as you say , unsuitable for windows that open.

I trust you are going to take said roll back to mc.

[alan_fincher]

I trust you are going to take said roll back to mc.

 

I'll certainly be having a conversation with them about it!

 

You are correct, the product you have would be my first choice for bedding windows down on to - it sorted out our last boat a treat, after the silicone that has been used throughout slowly failed on one window after the next!

[Rickent]

I've not started the job yet as am doing the leicester ring at the moment but it was a choice between butyl tape and butyl mastic. Tape should be a lot less mess.

I have eight windows to do, all of which leak to some degree and all with varying degrees of rust around the edges. I must admit it is not a job i am looking forward to.

[boathunter]

I've got some closed cell window tape here so I checked, not that I needed to, and no it doesn't soak up any water at all.

[alan_fincher]

I've got some closed cell window tape here so I checked, not that I needed to, and no it doesn't soak up any water at all.

 

Thanks.

 

Conversation due with Midland Chandlers, then, I think!

[MtB]

Preface the conversation by asking the purpose for which they sell this particular tape. You don't want the bloke heading you off by claiming it is just for draught sealing, after you've explained the problem!

 

I expect you've thought of this anyway though.

[boathunter]

 

Thanks.

 

Conversation due with Midland Chandlers, then, I think!

Mine was a fair bit cheaper too, for 25m roll, I got it from Caldwells in Wigan.

[Sea Dog]

I exagerated slightly when I said mine was 1/10 the cost - it was actually £2.50 for 10 metres (I think I bought 3mm x 8mm) inc delivery. It was more than enough to replace the sealing strip the opening glass rests on for 6 hoppers and 4 portholes. Seller was fastgaskets2000 via eBay.