old gelcoat in mould

Discussion in 'Fiberglass and Composite Boat Building' started by nevilleh, Mar 3, 2009.

  1. nevilleh
    Joined: Sep 2008
    Posts: 73
    Likes: 2, Points: 0, Legacy Rep: 53
    Location: scotland

    nevilleh Junior Member

    Guys, After a little advise.

    I have always believed that you should get the first laminate on top of the gelcoat within 4 - 6 hours.

    If it was left for say 36 - 48 hours do you think it is possible to wipe it down with MEK thinners to get that 'tack' back before laminating over?

    Is this advisable or should we scrap and restart? Guess what we have done!

    Also, we use cray valley encore 30 low styrene laminating resin - what in your opinion is maximum over laminating time ? again if we are ever over laminating say more than a week after last laminate was down we would key surface with a disc & wash with acetone - i wonder if this is required especially with a resin like encore 30 that has a bit of wax in it.

    probably a call to cray valley in the morning would put my mind at rest but i thought that one of you guys might know!


    thanks in advance. neville . scotland
     
  2. ondarvr
    Joined: Dec 2005
    Posts: 2,340
    Likes: 262, Points: 83, Legacy Rep: 506
    Location: Monroe WA

    ondarvr Senior Member

    Cray Valley is our sister company, we have North America and they have the rest of the world. Their formulas are different than ours because there are some different expectations and methods of use in other parts of the world.

    I'm not familiar with that resin, but any resin with more than a small amount wax will need to be recoated as soon as possible to ensure a good bond, if the surface isn't tacky then it needs to be sanded thoroughly.

    Gel coat is best used like you said, and should be skinned within eight hours. Many companies leave if overnight and some even over the weekend, but the sooner its skinned, the better the bond. Don't even bother with wiping it down with MEK, it may clean any dirt and dust off the surface, but if its been left too long and you have any doubts, just blow it out and re-gel coat.
     
  3. AroMarine
    Joined: Jul 2005
    Posts: 45
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    Location: Atlantic City NJ

    AroMarine Junior Member

    nev, if you have lost your window I think it depends on if your part is submersible or not and how big it is. If it is small enough to wipe down thoroughly ie lots of rags and lots of solvents and is not submersible you can get a good mechanical bond if your gel is cured and clean. There will be little crosslinking so water infiltration will be a concern for underwater or steamy closed area parts.
     

  4. maxsalgado
    Joined: Mar 2009
    Posts: 17
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Santiago, Chile

    maxsalgado Junior Member

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