How to tell if there is still wax on the surface of your fiberglass?

Discussion in 'Fiberglass and Composite Boat Building' started by midcap, Mar 28, 2014.

  1. midcap
    Joined: Oct 2013
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    midcap Junior Member

    I am replacing the transom in my hull and the area was sprayed with gel coat, that I assume used wax to get the surface tack free. The repair was made probably 5-7 years ago.

    I am worried that since I didn't use a wax solvent like this
    http://www.wholesalemarine.com/interlux-fiberglass-solvent-boat-wash-wax-remover.html
    that I embedded wax into the fiberglass that I am going to do the repair over when I ground and sanded the old fiberglass down.

    Should I be worried, or should the wax be gone after those many years?

    Thanks.
     
  2. Grey Ghost
    Joined: Aug 2012
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    Grey Ghost Senior Member

    I've done a few small repairs and I always wipe it down really well with the Interlux 202. 20 dollars is cheap enough I'd rather be safe.
     
  3. midcap
    Joined: Oct 2013
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    midcap Junior Member

    Is it ok to wipe down after the sanding is done?
     
  4. SukiSolo
    Joined: Dec 2012
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    SukiSolo Senior Member

    Do you mean wax (styrene monomer) was added to the gelcoat when it was sprayed? If so it should have been cut off by light wet sanding and buffing. Best and safest thing is to 'scarf' in any repair in glass and resin (polyester or epoxy) then rebuild top gelcoat. It is not that different from replacing say a piece of ply in many ways, though you may need a flat releasable internal former to hold it whilst setting off. Stiff polythene or polypropylene sheet can do this on moderate and small sizes.

    As a precaution when applying the new surface gelcoat (with wax added) you should wipe the existing old surface with acetone to clean off any surface contaminents. Most of your surfaces will be cleanly abraded anyway or fresh new resin so I can't se too many problems. Normally after setting off the new gelcoat you wet and dry it down working through grades to say 1000 or 1200 then buff out with a polishing/cutting paste. Fun bit is matching the colour - there are an awful lot of whites....;)

    If you find hollows that need to be refilled, yes you must cut the surface back as the wax sits there and is a barrier and release agent, which will not allow a subsequent coat to bond. Personally if I get this, I get quite agressive using 80 or 120 grit to abrade the surface in the hollow ensuring all wax has gone, and also wipe with acetone prior to second application.
     
  5. ondarvr
    Joined: Dec 2005
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    Location: Monroe WA

    ondarvr Senior Member

    The chance of having wax still on the surface after 5-7 years is slim, and since you hopefully sanded the area with very coarse grit grinding disks the possibility of having wax create a bonding issue is almost nonexistent.
     
    Last edited: Apr 4, 2014
  6. midcap
    Joined: Oct 2013
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    midcap Junior Member

    Thanks for the info, my gel coat has been completely removed from the interior of the transom due to the repair job being subpar. So, I don't have to worry about blending gel coat colors because the new gel in the bilge will all be the new white color.
     

  7. midcap
    Joined: Oct 2013
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    Location: United States

    midcap Junior Member

    36 grit on an angle grinder. I am going to pick up some interlux 202 this week. I couldn't do any glass work yesterday as it was too cold. This winter has been brutal.
     
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