Metal Flake/ Gelcoat Repairs

Discussion in 'Fiberglass and Composite Boat Building' started by TBC Marine, Feb 22, 2022.

  1. TBC Marine
    Joined: Feb 2022
    Posts: 3
    Likes: 0, Points: 1
    Location: Pierz Minnesota

    TBC Marine New Member

    I'll be short and right to the point. Last two boats I sprayed I am getting these small pinholes in my gelcoat as well as on the edges where the gelcoat is thinner on the repair it appears to not Curing very well. If I go to clean it up at the end prior to buffing with acetone (days later) it just gels up. Shop is kept at 75 degrees is a very air tight building so dehumidifier running and kept it at around 39% and a few fans running away from the project for some air movement. I'll give a brief of my mixes and what I'm doing. Prep work- sanding area with 80 grit, clean with acetone tape off. Metal Flake was mixed with 3% styrene, 1.5% MEKP Gave it 3 coats of flake as it took this many to give a good cover up of the previous colors. I than gave it 3 coats of clear. First 2 coats gel, with 1.5% MEKP, Final coat mixed with 50% Duratech 2% MEKP. Shooting with a 3m accuspray 2.0 tip for metal flake, 1.6 for just the clear. I have the 26837 conversion pack and the 26124 H/O pressure cup which was instructed by 3m for shooting flake/gelcoat out of this gun to regulate pressure better. Roughly 30-45 minutes before coat. can rub hand down each time without feeling wet etc but is tacky. The pinholes almost go all the way down as by the time I get a good smooth finish my coats are all gone to the original. SUPER FRUSTRATING. Any ideas? Tried to be as detailed as possible as I know there are a number of things that can cause this. Thanks in advance.
     
  2. TBC Marine
    Joined: Feb 2022
    Posts: 3
    Likes: 0, Points: 1
    Location: Pierz Minnesota

    TBC Marine New Member

    I should also state my gun pressure is 20 psi. Here is a photo of what I'm talking about. I had about an two inches of the clear gel left in my liner- which all cured smooth as can be....
     

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  3. gonzo
    Joined: Aug 2002
    Posts: 15,818
    Likes: 1,221, Points: 123, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    Do you have an inline filter on the air hose? Also, it should be a clean hose. Washing the inside with hot water and dish detergent works well.
     

  4. TBC Marine
    Joined: Feb 2022
    Posts: 3
    Likes: 0, Points: 1
    Location: Pierz Minnesota

    TBC Marine New Member

    We do. I did a couple practice runs on a junk fiberglass boats and it almost seen as though it was spraying WAYYYYY to fast out of the gun throwing it everywhere..... Got it tamed down a bit/sanded and just shot it again will see how it turned out in the morning fingers crossed. Never had an issue with it at all and obviously if its curing in the cup smooth as can be its not a mixture problem only other variable is air/spray gun.
     
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