# Does DOW 795 ever cure, bond or dry?



## anerussis (Dec 26, 2011)

As previously posted I surface installed new windows on my C&C 26. As suggested i used Dow 795 caulking. Now more then a week later this Dow stuff is still tacky and soft. I smeared a line of it between two scraps of left over pieces of 1/4" acrylic and several days later I was able to very easily slip them apart. It seems that this stuff has no more bonding strength than ordinary water. I am now very glad I also used double sided tape and some screws.


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## flyingriki (Sep 27, 2012)

Description
Dow Corning® 795 Silicone Building Sealant is a one-part, cold-applied, non-sagging silicone material that cures to a medium modulus silicone rubber upon exposure to atmospheric moisture.

This seems like an odd way to cure and am not sure what the advantages are.

I'd be curious where you got the advice to use this. I'm not familiar with it and may have to redo some ports, hence my interest....


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## anerussis (Dec 26, 2011)

I think that if you google search "Dow 795 sailboat " you will find much info.


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## floridajaxsailor (Aug 4, 2010)

*.*

Good to see you amigo I was literally thinking about you today amid thoughts of the window replacement issue

In regards to the windows I'm still scheduling when I am going to do mine- probably in early November before I leave for the islands

I have been looking at several options, further, curious how you wrestled with the aluminum framing, if you did damage any sections, & did you replace it and how!

I was going to put in a solar vent this week- one of the VERY knowledgeable old-timers from the marina suggested using GE silicone, perhaps this:
http://www.caulkyourhome.com/ge-silicone-II-paintable-silicone.php
though I will ask him tomorrow- a remarkable attention to detail person, once mentioned to me he built custom boats during which the final phase involved lining up the slots on the Philips heads!

Curious about the 795 too as I remember some poster raving positive~ now I'm quite skeptical

Sure you could use some of our wonderful Florida weather for the next 2 weeks to help you dry out the product- several days of Blazing Sun... ignore the fact that were in the middle of a hurricane, yet you know what I mean 
take care
-JD


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## flyingriki (Sep 27, 2012)

You got me interested so Googled some more. Here is some intelligent sounding advice:
Dow Corning 795 - Cruisers & Sailing Forums

Still funny that it only cures in atmospheric moisture. That seems to mean only the surface, but that may be the design while the interior of the bead stays soft until it gets exposed to moisture.....?


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## anerussis (Dec 26, 2011)

*Re: .*



floridajaxsailor said:


> I have been looking at several options, further, curious how you wrestled with the aluminum framing, if you did damage any sections, & did you replace it and how!
> 
> -JD


Did not re-use the frames - just surface mounted the plexi using automotive tape, Dow 795 and few screws. Have posted my procedure. The windows look good however a bit bothersome that the silicone and tape lines can be seen on close inspection. The Dow 795 compared to regular silicone is easy to work with in that it doesn't seem to be as sticky and takes a very long time to skin over. Another poster has advised that it needs moisture to cure which seems to explain why it didn't cure between my scrap plexi test pieces. However this is not mentioned anywhere on the tube instructions etc. I am wondering that if this stuff doesn't cure unless it comes in contact with moisture would it start runing between the plexi and the fiberglass under a hot summer sun.


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## jrd22 (Nov 14, 2000)

I resealed our pilothouse side windows with it (DC795) and it cured to a rubbery texture much like 3M 4000. No leaks, very happy with it. It is designed for all kinds of glazing, including high rise buildings so I'm not sure what is going on with yours but it doesn't sound right.


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## Faster (Sep 13, 2005)

I've used DC 795 on several occasions, including once where a window cracked and I had to replace it. At that time the 795 had already been in place for about 4 years.

I removed the screws and yes, I was able to 'pry' the window off, but it did stay in place initially. Some of the 795 stayed with the window acrylic, some stayed 'stuck' to the cabin side. The stuff stuck to the cabin side was easy to cleanly remove by getting a scraper underneath it, it peeled off like a rubber gasket. It was soft and pliable, but not wet.

To me this is an advantage.. imagine trying to get 4 year old 4200 or 5200 off easily. I don't mind using the screws to hold the window down, having two methods of fastening never hurts. I wouldn't ever rely strictly on its 'adhesive' properties for an application like this. An office building fixed glass panel is another thing altogether.

One other thought... the stuff definitely has a shelf life and the tubes have a 'best before' date stamped on them.. maybe you got an old batch.


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## anerussis (Dec 26, 2011)

Faster said:


> One other thought... the stuff definitely has a shelf life and the tubes have a 'best before' date stamped on them.. maybe you got an old batch.


Oh no...... just checked one of the tubes and on it was stamped 2010 -- so it seems they sold me old stock ------ on the pluss side yesterday I checked the windows again and the perimeter bead seems to have solidified although I am still able to leave a finger nail impression when pressing on it.


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## Donna_F (Nov 7, 2005)

I'm going to slide this thread into a more appropriate forum.


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## msmith10 (Feb 28, 2009)

Dow 795 is great stuff, but definitely has a shelf life. It's an architectural adhesive/sealant for glass. I've found it to be very strong, highly elastic. When it's past it's shelf life, though, it has a very funny cure. If it's too old, you can tell as soon as you apply it- it feels more like polysulfide than silicone.


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## anerussis (Dec 26, 2011)

msmith10 said:


> Dow 795 is great stuff, but definitely has a shelf life. It's an architectural adhesive/sealant for glass. I've found it to be very strong, highly elastic. When it's past it's shelf life, though, it has a very funny cure. If it's too old, you can tell as soon as you apply it- it feels more like polysulfide than silicone.


On the tube is stamped Oct 10 -- so i assume Oct. 2010 -- is it too old? Will it eventually to the job or do I need to re-do the windows? 
Also I had just wrapped the nozzle of the leftover tube with some saran wrap and when I tried it early this morning the stuff came out easily as if I had just broken the seal - is this normal?


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## anerussis (Dec 26, 2011)

anerussis said:


> On the tube is stamped Oct 10 -- so i assume Oct. 2010 -- is it too old? Will it eventually to the job or do I need to re-do the windows?
> Also I had just wrapped the nozzle of the leftover tube with some saran wrap and when I tried it early this morning the stuff came out easily as if I had just broken the seal - is this normal?


Just found the Dow specs for the Dow 795 - and now I realize whats happening ---" In totally confined joints (the sealant
requires atmospheric moisture for cure)" 
In using this Dow 795 the more is not better- My window situation is because I believed the opposite and pumped as much of this stuff as I could in the joints. Also I think the reason my small test pieces did not bond is because the bead I applied was in the center of the pieces and sitting at the corner of my office desk and since there was no moisture present the silicone did not cure.
I would include the specs in pdf format but I don't know how.


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## GaryHLucas (Mar 24, 2008)

I believe you got some old stock and it will never cure remaining like silly putty forever. I got sold old stock as well for my windows and contacted Dow. They told me never to use 795 beyond its use by date. Oh what fun peeling all that stuff off! The vendor gave me fresh tube and it cured with no problems. Sorry for the bad news.


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## flyingriki (Sep 27, 2012)

DRFerron said:


> I'm going to slide this thread into a more appropriate forum.


Wow! The moderator is a BABE......how nice!


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## mitiempo (Sep 19, 2008)

From Select Plastics - the largest hatch remanufacturer in the business - temp has to be above 50 F for the entire 21 day cure.


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## SloopJonB (Jun 6, 2011)

flyingriki said:


> Wow! The moderator is a BABE......how nice!


Not only that - SHE hunts down & buys the boats in her family. I think her husband struck more gold than Sutters Mill there. 

Edit: Quote:
Originally Posted by DRFerron 
We're pretty much doing the same with our next boat. He gives me his list of requirements, I find the boat and he writes the check. Works perfectly for us.


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## MikeinLA (Jul 25, 2006)

PLEASE don't ever use the phrase "DOW 795" in a title again.  I haven't checked my stocks in a few weeks and I almost had a stroke. :laugher

Mike


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## SimonV (Jul 6, 2006)

Dow 795 is perfect for through deck chain plate seals as it never truly cures . If using it in a place where someone may step or touch, I found a sprinkling of talc over the out side helped.


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