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Thread: Replacing Porthole Glass

  1. #1
    Join Date
    Oct 2004
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    South Jersey
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    Default Replacing Porthole Glass

    Anybody have any suggestions for removing the glass from a rectangular, bronze ABI porthole? I had one crack and have the replacement glass. Would heat be the trick to release the bedding compound? What type of compound would be best to use for seating the new glass? Thanks.

  2. #2
    Join Date
    Apr 2006
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    St. Augustine, FL
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    5,863

    Default

    I have one of Sarah's round bronze portlights with the same issue. I plan to march it in to the local glass place, get a quick education on the types of replacement glass (I'm guessing something tempered), make a decision, and return a few days later and pick up the piece all done.

    Seriously, unless you've got a bunch to do, why try a new learning curve and buy some new gloop, which you'll only use a small portion and leave the rest sitting on your shelf with your other gloop collection.

    You'll be getting the glass cut somewhere right?

  3. #3
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    Oct 2006
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    Dooral Dooral, Eastern Oz
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    Default

    I've done many round ones - with screw in rings. I made my own tool to release the glass from a bit of steel bar.

    Never done a rectangular one, but have you tried a hot knife to release the bedding compound?
    Carpe the living sh!t out of the Diem

    I'd rather look back at my life and say "I can't believe I did that" instead of being there saying "I wish I'd done that"

  4. #4
    Join Date
    Dec 2004
    Location
    Maine
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    Wink

    Honestly, it depends on the goop.

    If it's proper boatyard bedding compound, I've had success with incrementally tapping in many small wooden wedges.

    If the sucker is held together with 5200 or sikaflex or the like, apply heat from a heat gun and again, drive in wedges. You can get a heat gun from most hardware stores for 15-20 bucks.

    The only trick is patience. Lots of very evenly distributed force.

    -Cullen

  5. #5
    Join Date
    Dec 2004
    Location
    Maine
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    Default

    Oh, and as to re-bedding the new one:

    1. REALLY clean out the rings. I mean really. Heat, scrape, sand, do what ya gotta do. Make it nice. Show it to Mom. See what she thinks. Then clean it one more time.

    2. If you use boatyard bedding compound, (which cleans up easily and is nice because it repels water and stays gooey for a long long time) Use a nice fresh can. Old cans of compound get lumpy. The lumps impede the glass from sitting cleanly against the frame of the port. Spread an even coat inside, set the glass in, screw it back together. GO SLOW! That goo wants to slop out the edges, and that's a good thing. If you have an even squirt coming out all the way around, then you have a nice bronze/goo/glass sandwich with no voids. Scrape away the extra compound. Mineral sprits can help with residue.

    3. If you choose some polysulfide marine sealant (and may you suffer accordingly), I'd recommend placing the glass into the frame "dry" and marking the rim with a felt pen. Pull it back out and tape the Inside of the glass surface with 3m painter's tape to keep the aforementioned P.M.S. from making a horrible mess.

    Good luck!

    -Cullen T.M. McGough

  6. #6
    Join Date
    Feb 2000
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    San Francisco Bay
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    Actually, I've had excellent results over time using plain old silicone caulking goop to bed glass in marine applications. The silicone fills the voids well and is easy to cut and scrape off of the glass when cured. It has very good compressability, which is what you want in a bedding compound. Most cracked glass I've encountered was the result of bedding compound that got hard. When the frame material (most often wood, but also bronze in port lights) expands with moisture absorption or heat from the sun, and the bedding is hard, the glass is the weakest link and cracks.

    I've found the best glass for replacement is standard automotive safety glass. Your glass shop can cut it to size for you. Some older portlights use very thick plate glass, which you will have to use if replacing a similar material, but if you can get away with ordinary auto glass, I'd say go for it. I have not been happy with polycarbonates and other plastics which either craze when soaked in UV or scratch over time.

  7. #7
    Join Date
    Oct 2004
    Location
    South Jersey
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    Default

    Thanks, everyone. I have the replacement glass from ABI. I think I will try a little heat from a heat gun to get the old stuff out and will use the suggestion of plain old silicone caulking for setting the new glass.

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