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Don Z.
06-13-2006, 08:58 AM
OK, I know there are a lot of opinions on this subject, but I want to do this correctly.

To make a long story short, as I was prepping the cabin for varnish on the Chris, I found some rot under one of the bedded in deadlights. This lead to pulling out the glass... where I found that the previous owner, in trying to repair a leak, relied on some sort of silicone... Lots of silicone... gobs and gobs of it!

So, I got the glass out last night, and will spend most of my time today scraping this stuff off, and then repairing the rot with a dutchman. Then what?

The way the boat is designed, the glass lays against a rabbet in the wood, and then another piece of wood is screwed in to hold the glass in place. Then, a trim piece covers the work. Because I don't want a future owner to direct some of the same curses I used last night towards me, I'll use bedding compound on those trim pieces, not the same silicone that the PO used...

What is the best way to bed in these deadlights? I know they may leak a little (I found the weep hole that the PO had plugged!), other than slathering on life caulk or some other goop... I was thinking a light coat of life caulk, then replacing the wood... followed up by interlux glazing compound once the life caulk cures.

Sorry if this seems a bit "scattered"... I was up really late last night, pulling the glass out!

Figment
06-13-2006, 09:37 AM
Polysulphide may be more friendly to the wood, but I've always had better luck with butyl rubber (generally marketed for gutter work) when sealing glass to anything. It's horribly messy stuff to work with, but if you only want to do the job once.....

edited to add: really, test its reaction to wood before going whole-hog. I've only used butyl in bedding glass to metal. I've never had it in contact with wood.

Matt J.
06-13-2006, 09:41 AM
Ours are bronze against the wood (bronze encased glass) and the lights were bedded in lifecalk. I'd planned on repeating the same mistake for lack of a better compromise. I was actually going to re-bed them this weekend since the cover's off and the varnish has been refinished.

George Ray
06-13-2006, 09:56 AM
No matter how good the bedding compound is, mositure will work it's way under it to some extent. The preparation of the wood prior to setting the light in the bedding is the key. I would also argue that the bedding 'SHOULD NOT' be glue (5200). You need to be able to get the light up and reprime the wood whenever you see any signs of weirdness, hopefully it will be about every 12-15 years.

What to use for prime is a good question. Hot oil soaked repeatedly into wood/endgrain/cracks has got to promote longevity. It can be tung/linseed/thinned pinetar/clear sealer/ thin epoxy/ on and on and on, but no bedding will work if it is put down on bare wood or or wood that is just skim coated, surface primed.

Thorne
06-13-2006, 10:08 AM
Dare I suggest multiple coats of CPES for the prime?

(climbs into trench, puts on helmet, hunkers down...)

;0 )

Don Z.
06-13-2006, 10:40 AM
Yes, I'm planning on using CPES... and I will NOT be using 5200... not even 4200!

paladin
06-13-2006, 12:11 PM
a small work of caution.....if the glass was truly bedded in silicone...and it is in the wood.....it may inhibit anything else from sticking...cpes or anything........I coated the wood on Amihan with epoxy, then used heavy lexan and bathtub caulk......and about every three years removed the panels, cleaned off the old stuff, put new stuff on, never had a leak....well at least not in the deadlights...:D

Bob Cleek
06-13-2006, 05:44 PM
After sealing with CPES, I've found household silicone is a good bedding option. This is because it is resilient, doesn't harden, and is very flexible. In the past, I've had problems with other compounds. The interface of wood and glass brings together two materials with radically different expansion and contraction properties. A tight fit bedded in anything that will harden over time is almost certain to crack the glass when the wood shrinks against it. On the other hand, a loose fit will leak. Since using silicone, I haven't had that problem.

Don Z.
06-14-2006, 08:27 AM
Bob,
When you use silicone, do you have difficulty varnishing near it afterwards?

Bob Cleek
06-14-2006, 02:25 PM
Absolutely! There's no way that paint or varnish will stick to silicone. However, as most windows have some sort of trim ring around them, this isn't a problem. I tape to keep the silicone from spreading where I don't want it. I then bed the trim ring over the silicone with Dolphinite bedding compound.