Techniques to rebed dead lights (windows)

[Benjamaphone]

[quote=hellosailor;143261]
You're using something a bit more advanced, with a special primer, to get that bond?
quote]

Yes, except I don't believe that its all that advanced as far the newest and coolest goes. We've been using that same process for some 30 odd years. When we get hatches back for repair, its always at least 15 years later, and almost never a problem with the seal around the glass. I don't really want to divulge the exact chemicals/process but it goes something like this; the old glass is taken out, ALL the old sealant and any dirt is removed, a new piece of glass is cut, rounded and shaped, a solvent is wiped around the edges of the hatch frame and the glass to remove oils and the of the last dirt. Then we use an acrylic primer, that to my best understanding, etches both surfaces, around the frame and glass. Next, the glass is put into the frame loose, spaced out evenly with about an 1/8" on all sides/corners, and an excess of a silicone product is forced into the groove with an air gun type machine. The excess silicone is cleaned up and given a finished look and then the hatches are left to cure completely without bumping or touching for at least 5 days at a stable, relatively warm temperature.

The end result is product that does not leak, can handle the thermal expansion and will last another 15-20 years without need to be re-serviced.

"Interesting that you prefer a sealant that will adhere to the glazing, as opposed to a floating seal."

Our process ensures that the glass will float in the frame with thermal expansion/contraction. The flexibility of the silicone and etching by the primer that we use means that it makes a strong bond with the acrylic and the frame while being able to "float" and avoid cracking any seal.

I hope this clears up any confusion and I apologize for not knowing more about the complexities between the whole Acrylite/Plexi relationship. As far as silicone not sticking to Acrylite, I can categorically say that is not true. Like I said, this process has worked for 30 years and if there was something better we would have adopted it already.

All of our products are first designed for our boat before they go to market. Often we are just solving problems around the boat and a new product comes out of that. This has meant that if we find any problems they get fixed fast or we get wet! There may be other solutions to some of these problems but we believe that our solutions are the best solutions because they've worked the best for us.

[hellosailor]

"As far as silicone not sticking to Acrylite, I can categorically say that is not true."
Trust me, that's because the stuff you are using isn't what we buy at the corner hardware store.<G> And, you are etching with a primer. If you pick up a tube of generic silcone seal from the hardware store and lay a bead on a piece of generic acrylic from the same hardware store--you can peel it off clean, once it has totally dried and cured. It will resist a bit at first, but if you leave it out for a while, give it some time and UV, eventually it will let go. As will generic epoxies and many other adhesives, they just don't like plastics in general.

[Benjamaphone]

Originally Posted by hellosailor

Trust me, that's because the stuff you are using isn't what we buy at the corner hardware store.<G> And, you are etching with a primer.

That is true, and I hold that as a standard for everything that we do. By going above and beyond the first time, you won't have to worry about it again for many years to come. These products are available to the general consumer through specialty hatch manufacturers.

[Northeaster]

Any suggestions on brands / where to buy primer for acrylic deadlights?

[GordMay]

Sika Primer-209N is used to prime painted surfaces and plastic substrates, such as Acrylic, Polycarbonate, & ABS etc., prior to bonding/bedding with Sika products.
Goto: http://www.sikaindustry.com/tds-ipd-...209-ind-us.pdf