Polyester Resin Tack-free Strategies

Discussion in 'Boatbuilding' started by Cal79, Oct 14, 2018.

  1. Cal79
    Joined: Oct 2018
    Posts: 1
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    Location: UAE

    Cal79 New Member

    First time poster here!

    What is the best lamination strategy to have a tack-free cure for laminating with polyester resin? The method I use is to add 2% wax to the resin for my last layer of fiberglass. This works well for me, but I am worried it might be weakening the laminate in the long-term. Anyone know if using wax on the last ply weakens the lower plies long-term?

    Should I switch to brushing a layer of PVA on the last ply and forget about the wax altogether? Any practical comments / suggestions?
    Last edited: Oct 14, 2018
  2. Blueknarr
    Joined: Aug 2017
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    Location: Colorado

    Blueknarr Senior Member

    Welcome to the forum.

    Wax can't migrate into previous layers of fiberglass, so it can't possibly weaken them. Residual wax may/usually interferes with the bonding of any additional layers after any waxed layer. Wax additives have a long history in polyester glass work. If there was an weakening issue, it would have manifest it long ago.

    The decades I spent as a commercial painter made me biased against adding wax. I am now doing fulltime fiberglass and gelcoat repair. The gallon can of wax surfacing agent I bought three years ago is still well over half full. I do use a lot of PVA.

    Almost all of the cloth I lay will require some grinding/sanding back to be fair with original surface profile. I accept the clogged abrasive disks on small repairs. On medium to larger ones, I'll use peelply. I don't PVA over cloth out of concern that it will be difficult to remove from the pits in the weave.

    I almost never leave new cloth ungelcoated. Just the nature of repairs.
  3. ondarvr
    Joined: Dec 2005
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    Location: Monroe WA

    ondarvr Senior Member

    Don't over think it, if the wax works for what you’re doing then stick (pun intended) with it.

    I will add that the average shop doesn’t use wax in resin very often, most never do.

  4. KD8NPB
    Joined: Mar 2018
    Posts: 143
    Likes: 30, Points: 28
    Location: South Carolina

    KD8NPB Senior Member

    The ISO/DCPD I use dries tack free.

    Ashland Aropol L67300-series. C1 churns out L67303T40 like water.
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