What do you make of the white stuff?

Discussion in 'Boatbuilding' started by bilgeboy, Apr 30, 2006.

  1. bilgeboy
    Joined: Dec 2005
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    bilgeboy Senior Member

    While trying to fix a rotten bulkhead, I decide the adjacent floor should come out, too. Mostly just for better access to the bottom of the bulkhead. It wasn't in that bad shape, really, but I thought this white discoloration was interesting. I thought it was mold at first, but does not come off, and has the same feel as the resin on the wood.

    Kind of an interesting pic. This is a clickable thumbnail.

    [​IMG]

    I was curious if this is hydrolytic degradation from the tendency of polyester resin to "absorb" water. The side that looks more white had a puddle of standing water under it, about 2" below.

    Curious to see if folks here thought that was a correct assessment of the white stuff.

    Mike
     
  2. TuckSail
    Joined: Jul 2004
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    TuckSail Mechanical Engineer

    are you sure it is not overspray from a gelcoat application?
     
  3. bilgeboy
    Joined: Dec 2005
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    bilgeboy Senior Member

    Yep. Thats a good thought, though.

    You are looking at the underside, that is the access door for bilge pump access, and you can see the two lines where this piece rested on stringers.

    The discoloration is not on the floor directly underneath.

    Its not keeping me awake at night, but I was curious.

    Thanks,

    Mike
     
  4. Ike
    Joined: Apr 2006
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    Ike Senior Member

    It's probably wax. Many resins have wax added to resin. The wax rises to the surface and blocks the air from getting to the resin, which helps it to set more rapidly. When it reaches the surface it turns white. You can remove it with acetone. This generally is found in resins you buy across the counter to do small glass jobs.
     
  5. gonzo
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    gonzo Senior Member

    I've seen some polyester resins absorb enough water to get milky. They get clear again after drying.
     

  6. bilgeboy
    Joined: Dec 2005
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    bilgeboy Senior Member

    I'll hit it with some laquer thinner to see if I can remove it, Ike. Its not going back in, but this hands on stuff is really the only way to learn, No?

    I've been working with epoxy and polyester resins the past few days for the first time in my life. Wow. I can read here all day long but the real education comes from incidents like accidently getting some saw dust in your epoxy, and trying to figure out how in the hell you've just started a fire in your mixing cup. Talk about "kick!" I read the manual that night and figured it out, but that was quite an education in composites.


    Mike
     
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