Epoxy Pinhole Question

Discussion in 'Sailboats' started by BobBill, Oct 5, 2010.

  1. BobBill
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    BobBill Senior Member

    Arrggghhhh! As C Brown was fond of shouting. I did search and am still going through hits, but none seem to deal with similar result. I know I can grind the material down smooth, but

    The pic best describes my irritation. I glassed a portion of hull, two coats and have since decided that peel ply is not my friend; unnecessary if sanding is required anyway.

    Second layer of glass. Pulled the ply off and it took some of the epoxy along with it, it seems, as it gathered up the excess...in the mat as noted. Long cure...24 hours, so the mix was hardened.

    Sand or add one very thin coat and sand?

    Using polyester I never encountered this problem, but live and learn.

    Thanks.













    epoxy pinhole
     

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  2. Doug Lord
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    Doug Lord Flight Ready

    Last I heard mat must specifically say that it is compatible with epoxy-if it doesn't then it isn't.
     
  3. BobBill
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    BobBill Senior Member

    Peel Ply is Problem

    Can't say I heard of that, glass cloth is what it is... All materials acquired same establishment.

    The epoxy and glass are fine bonding etc. I just have these slight dimples in some areas that appeared when ply removed and sanding. The reason I am fairly certain of cause is because the ply was folded and where it tended to pull away where there was a crease, the glass had few dimples if any.

    Looking for some knowledge is all, or experience with similar problem.

    Been using poly for decades and occasional epoxy, without incident, but then I sanded the layups with a auto grinder sans ply and work looked find and took paint well. Just curious if someone had similar ply problem and added a second coat, not that heavy, or simply sanded heck out of it to get even surface.
     
  4. Doug Lord
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    Doug Lord Flight Ready

    The problem is the binder. Most chopped strand mat is designed for use with polyester or vinyl ester-the stuff tends to be hard to work on curved surfaces with epoxy and the binder never dissolves.

     
  5. waikikin
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    waikikin Senior Member

    BobBill, that looks like a light cloth, with partially entrained bubbles in the weave, you need to saturate the peelply more to fill the weave under the peelply as the peelply can "scavenge" some resin from the cloth, also handle the peelply carefully to not crease it, even strait off the roll, never fold it, also slit it to narrower width for use over compound curved areas- you can roll it onto lengths of pvc storm pipe for easy roll out handling & I always slit the selvedge off the edges as it tends to pucker there if you leave it on, also fold back dog ears on the top layer at any overlaps to give an easier start for peeling it off. For what you've got there I'd sqeegee or broadknife some
    thickened resin into those "holidays". All the best in your endeavours from Jeff. PS: At the least your humour is intact----- Arrggghhhh! As C Brown was fond of shouting
     
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  6. BobBill
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    BobBill Senior Member

    Peel Ply is Problem

    Thanks.

    You know your stuff. You are correct. Two separately cured layers of 4oz cloth.

    This last segment of ply was folded and I complained but had to do job so went ahead. Must be on roll, no creases as you observed.

    Still, the ply did suck up too much, IMO. I over saturated glass to compensate and ended up with the "holidays" as you noted. The ply took it up and more. I could see it above ply as it cured. It was hard to remove and I had a sneaking suspicion it would remove cured resin in the weave. Too late then...Duh on me.

    The first layup and coat was likely the same, but did not sand so the impoverished cloth went undiscovered.

    I will likely do as suggested and add light coat of resin this noon, after a thorough wet wash and wipe with denatured alcohol. Figure another half pound or so will not be critical on this project. I could sand into cloth to gain fair surface, but sanding is so tedious.

    This should serve to school others before they encounter similar situation. I never used ply in past but decided to give it a go, and

    A) Ply did job with first coat, eliminating the blush, and was necessary in that respect. Of course, non blush epoxy could be used too.

    B) Ply is not necessary if the final finish must be sanded for paint, unless using polyester resin which is very ugly blush.

    C) Gel coat would require the ply and the missing resin should not affect gel coat finish, but not absolutely sure on that count.


    Arggghhh! Was all I could think of.

    C'est le vie! We learn and smile.
     

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  7. Herman
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    Herman Senior Member

    If ply means peelply, you should laminate it with more resin. The peelply needs resin as well!

    Most peelply is 85 grams / m2, and it eats up the same amount of resin, approx. Use a bubble buster to compact your laminate, and to push the peelply down. You do not want the peelply to float in the resin.
     
  8. BobBill
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    BobBill Senior Member

    Peel Ply is Problem

    I did exactly as you describe. The excess resin pooled above ply, used metal roller.

    Wasted time and money anyway, as ply is not needed if sanding needed before primer etc. only if gel coating or another layer is next step, as I see it.

    I goofed. Hope this helps others.
     
  9. PAR
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    PAR Yacht Designer/Builder

    In all but the most professional shops, where you'll have climate control and are doing bag or infusion work, you can assume you'll have a blush, regardless of resin type used, so cleaning and abating the surface is necessary. Peel ply is a waste of time in air cured, hand layups.
     
  10. BobBill
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    BobBill Senior Member

    Peel Ply is Problem

    Hi Par,

    As you noted, and as I discovered above, but we learn. A little time lost and some epoxy. Not a biggie. Its the learning and outcome that means most. The ply application on the first layer of glass seemed to work as the second layer adhered well but needs finish coat or long grind to smooth...

    My little Kite project has moved me into today's plastics and is fun.

    FWIW, your advice and that of Steve Clark were well received and, with some ad-libs, working wonderfully. For example, I would never thought of using pipe insulation/epoxy for stiffeners and that ingenious suggestion opened my mind to lots of other alternative, like using Pool Noodles for interior flotation.

    Have posted some history under old thread so the other Kite owners can review, and will add to it when I get back to the work, which has been repeatedly delayed by weather and family matters. will not be finished until April or May as it is now. Winter looms.

    All the best.

     
  11. gggGuest
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    gggGuest ...

    There's some very remarkable "advice" in this thread... The SA thread would seem to be much more reliable.
     
  12. PAR
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    PAR Yacht Designer/Builder

  13. Doug Lord
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    Doug Lord Flight Ready

  14. tunnels

    tunnels Previous Member

    I see by the pictures you have too much resin in places and not enough in others so the glass is floating ,in places !! Never steel roll glass that thin !
    Use a short haired paint roller and do all your rolling with that Start in the center and work in all directions towards the outside . Once its hardened Roll a second coat of just resin with hardener ! The third coat mix some q cells with the resin and generous coat but not to the point if starting to run every where !! Then do your sanding !! Remember its the resin and q cells you are sanding not the glass !!! If you get to the glass move on !
    I prefer a short haired paint roller to a sponge as the sponge seems to pick up the glass if you roll to quickly . There should be no need ever to use a steel roller !:confused::p:D
     

  15. Herman
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    Herman Senior Member

    My prefered method is to squeegee the resin around. (and do all layers in one session)
     
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