Problems Applying E-Glass Over Plywood

Discussion in 'Materials' started by Monkey47, Apr 8, 2020.

  1. Monkey47
    Joined: Apr 2020
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    Monkey47 Junior Member

    Hi all,

    I'm trying to cover mahogany plywood with #1080-50 E-glass 1.45 oz/sq yard for a final finish using WEST 105 and peel ply. I've done numerous test pieces and continue to get bumps in the final cured surface.

    Conditions: 60 deg F

    My technique has been:
    1. Pre-treat plywood with WEST, let cure, and sand surface.
    2. Lay down fiberglass cloth and squeegee WEST making the cloth smooth and even
    3. Lay down peel ply and do the same, applying additional WEST as necessary get an even surface, squeegee out excess epoxy.
    4. Let cure.

    I consistently get small bumps in the final surface. I've tried continuing to smooth the surface with the squeegee while the epoxy gels which has helped some, but feels like a losing battle. I've also tried picking up excess epoxy with a dry roller which also helps a bit. I'm thinking that I must be doing something wrong that would make an expert laugh.

    20200219_172346.jpg
     
  2. Monkey47
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    Monkey47 Junior Member

  3. gonzo
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    gonzo Senior Member

    How do you apply more resin after the peel ply is down? They look like wrinkles. When you turn on the vacuum, the cloth is shifting.
     
  4. Rumars
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    Rumars Senior Member

    Try this: apply epoxy to ply, spread it around until ply is saturated. Lay glass in wet epoxy, wetout completely, peelply. Work on a falling temperature gradient.
     
  5. fallguy
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    fallguy Senior Member

    Can you show us a picture of the work in progress?

    I think you are floating the peelply.

    If you saturate the glass and consolidate it; you do not squeegee, but you apply the peelply; then you pull the peelply out edgewise until perfectly flat.

    It looks to me like you are overwetting the peelply. The glass gets wetted well and the peelply should need almost zero wetout.

    A way to tell for sure is to use a consolidation roller over the top of the pp and see if it lakes heavily on you.

    Also, if you want a glass like finish you can use 0.030 petg
     
  6. fallguy
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    fallguy Senior Member

    If the bubbles have glass in them; you are floating the glass. No glass, you are floating the peelply. I always finish with a consolidating roller. The squeegee lakes and puddles too much.

    Also, different peelplies also behave differently.
     
  7. Monkey47
    Joined: Apr 2020
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    Monkey47 Junior Member

    I mostly the temperatures have been stable around 60 F. I could try reducing temperature during the process like you suggest.

    I'm not using vacuum. Is that part of the problem?

    I don't have pictures in progress, but I could get some during my next test piece. I have been applying epoxy to the peel ply in order to get it saturated. I've found that just putting the peel ply on the glass doesn't normally result in the peel ply becoming saturated. Maybe I am over doing it? Done properly the peel ply should be an even color and saturated? Is there a particular consolidation roller that you would recommend? I've just been squeegeeing off excess.

    I'd like to paint over the final surface so I think the peel ply would leave a better surface for paint adhesion than a glass-like surface.

    Can you comment on how the different peel ply's behave? I'm using this peel ply: Vacuum Bagging Release Fabric https://www.jamestowndistributors.com/userportal/show_product.do?pid=3754
     
  8. fallguy
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    fallguy Senior Member

    I have used two different peelplies.

    one is very light and harder to get to lay down. - one of the reviews says this about the product you are using, the other is the stiff redline aircraft stuff; the aircraft stuff is heavier, but they will all float in to much resin

    I really think you are making lakes with the squeegee and adding a wetout to the peelply and floating it.

    I'd try a 1/2" bubble buster consolidating roller 5-6" long. Use the roller and try to get a more consistent layer of epoxy; then apply the peelply and stretch it to even.

    Then run the consolidation roller.

    Try to not wetout the peeply one time. Just because it has a dry spot here and there on top doesn't mean you don't have full contact.
     
  9. fallguy
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    fallguy Senior Member

    60 degrees is actually cold; do not go lower; cold temps result in thicker epoxy and less likely to lay down

    you actually want warmer temps for better results, but not rising temps
     
  10. Monkey47
    Joined: Apr 2020
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    Monkey47 Junior Member

    Thanks fallguy. I'll try your suggestions and report back. I might have to wait for a warm day in the northeast for my shop to get warm enough.
     
  11. Rumars
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    Rumars Senior Member

    The ideea behind a falling temperature gradient is to avoid outgasing. When the wood is cold then starts to heat up, air trapped into the pores expands and forms tiny bubbles under the curing epoxy. If the wood is warm and then cools down, the air in the pores contracts and sucks the epoxy in, avoiding the problem. Unless you are in a climate controlled shop that maintains a constant temperature overnight, it's best to begin fiberglassing in the afternoon. You can actually simulate this on a test piece, heat it with an airgun then fiberglass.
    From your description I think fallguy is right and you are floating the peelply. It's better to overload the glass and suck some epoxy out with the peelply then the other way around.
     
  12. ondarvr
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    ondarvr Senior Member

    Squeegees work very well to distribute and remove excess resin, but its all in the technique, it's a learned skill.
     
    Rumars likes this.
  13. Monkey47
    Joined: Apr 2020
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    Monkey47 Junior Member

    That makes sense. I'll pay more attention to temperature trend in the future.


    I think I'm still working on this skill!
     
  14. Chris Rogers
    Joined: Apr 2020
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    Location: Boston, MA

    Chris Rogers Junior Member

    Is the peel ply coming right off the roll onto the surface with minimal handling? I have had this happen when there were distortions in the peel ply weave from handling or folding before it gets put down on the surface. No big deal with a bag but like this is can be a problem. Plain nylon (your red stripe stuff) should work best and I agree with the wetout roller over all after the peel ply is down - seems to help spread things out.

    Are you putting more glass on after this or going to primer/fairing?
     

  15. rob denney
    Joined: Feb 2005
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    rob denney Senior Member

    You may be stretching the peel ply, which slowly returns to it's usual shape, picking up epoxy as it does so. Do 2 samples.1 squeegeeing in the direction of the peel ply fibres. 2 squeegeeing at 45 degrees.
    rob
     
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