Can Fibreglass be invisible

Discussion in 'Fiberglass and Composite Boat Building' started by JohnMarc, Mar 9, 2019.

  1. JohnMarc
    Joined: Feb 2018
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    Location: Knysna South Africa

    JohnMarc <--- My ultimate goal

    Yes I know it sounds like a strange question.... What I am trying to do is make a table (and no doubt other bits of furnishings will follow if I am successful) using PVC foam and veneer for my boat. So what I did was trim some thin slivers of wood, which I laid on to some Biaxial on my glass bed and then laid the foam another layer of biaxial. The problem with my first experiment (besides the obvious air cavities) is that I was hoping the Fibreglass would disappear when the epoxy is infused with it. As you can see in the photographs it would seem the "thread" remains visible. I only used the Biaxial under the wood as I assumed it would facilitate the infusion. Otherwise I assume the wood flat on the glass would stop the epoxy flow. Is there another way I could do this ...... is there a material that I could lay on the glass under the wood that would facilitate the infusion process but "dissolve" completely (becoming invisible)
    entire.jpg close up layers.jpg IMG_7739.jpeg IMG_7741.JPG IMG_7743.JPG
     
  2. Mr Efficiency
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    Mr Efficiency Senior Member

    Seems like a lot of drama to make a table top. Is the glass reinforcement in anticipation of people dancing on the tables ? :)
     
  3. Mr Efficiency
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    Mr Efficiency Senior Member

    If you use cloth, you won't have any "evil" stitching showing, but I don't quite understand the rationale behind this idea, being averse to the idea of putting expensive materials into a table top.
     
  4. JohnMarc
    Joined: Feb 2018
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    Location: Knysna South Africa

    JohnMarc <--- My ultimate goal

    It is a table that will "sink" into the deck, so ha ha yes it probably will have people dancing on it:D

    Forgive my ignorance but when you say cloth..... what do you mean. The only reason I am using anything (re your question as to why I am using reinforcement) on the wood is for the infusion, or am I wrong ....
     
    Last edited: Mar 9, 2019
  5. Mr Efficiency
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    Mr Efficiency Senior Member

    Fibreglass cloth, available in various weights, but as to the suitability of that for infusion, or why infusion is even necessary, I don't know.
     
  6. JohnMarc
    Joined: Feb 2018
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    Location: Knysna South Africa

    JohnMarc <--- My ultimate goal

    This is only a trial run, if it works and the results are as good as the promising first experiment I will be doing them full-size .... I really like the finish on the glass. I am not too sure why you ask wether the infusion is even necessary.... doing a hand layup of the foam etc. just seems extremely laborious. Your Name "Mr Efficiency" surely suggests that it would make sense to you.....also I am having damn good fun seeing what all I can achieve with this infusion game, which you may have gathered I am extremely new to. P.S just running the new one now with the "cloth" (thanks for the tip) so far so good......
     
  7. Dejay
    Joined: Mar 2018
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    Location: Europe

    Dejay Junior Member

    Yes, I think you just need a "finish" type fiberglass cloth. You just used the wrong one. Maybe you need bleeder channels in the foam to avoid the voids. They do this for kayaks and canoes and it can look marvelous. Chesapeake light crafts and others have lots of videos on this.
     
  8. JohnMarc
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    JohnMarc <--- My ultimate goal

    Many thanks Dejay will have a look at the videos, and have found the fibreglass that you mention, went to look for it on my suppliers website following your comment, many thanks for the tips.
    Will post the results.
     
  9. Dejay
    Joined: Mar 2018
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    Dejay Junior Member

    I'd love to see your results! I'm a total beginner but I also have the idea of using fiberglass + veneer for vacuum infusion in a mold. Like plywood but theoretically cheaper material and maybe usable to be bend into shape in a mold. It looks like the large foam panel has blocked good resin flow in the center of the panel but the resin was able to flow a good bit along the fiberglass between mold and wood veneer.
     
  10. JohnMarc
    Joined: Feb 2018
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    JohnMarc <--- My ultimate goal

    Awesome will definately be posting the results as they happen, this is only the third thing I have tried with the infusion process. Actually didn't know the first thing about fibreglass or resin until maybe a month ago. This forum has been a great mine of information. I want to do a helm out of wood and foam. I am a keen amateur (with the emphasis being on amateur) woodworker and I am thinking of steaming wood and vacuum bagging it to my mould then doing the infusion afterwards...... what are your thoughts?
     
  11. Dejay
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    Dejay Junior Member

    Oh nice I've had the exact same idea! Using slightly wet veneer (maybe 2 or 3 mm) in layers into a curved mold. Maybe use somewhat green wood or just steamed. How "wet" is steamed wood? I have lots of crazy ideas around that but haven't tried it yet.

    Traditionally I this is called cold molding and done on a male mold. Overlapping two or three layers of thin planks and gluing them together to create a monocoque hull, but it's very labour intensive and messy. If you could fit the wood into a female mold and vacuum infuse it you would save a lot of time from fairing and sanding.

    For the mold I'd be looking at something like the molds used in the "intelligent infusion" of the harry proa design, build out of melamine plates with big fillets. Since you use that mold for 8 times for front, back, top, bottom and both hulls it might be worth making a propper plug / mold. So for specific hull designs requiring a mold isn't that big of a deal.

    There is a problem with forcing the veneer into shape until you can put the bag on. One idea was to constrain the edges of the mold so that the wood strips fit just right and can be "wedged in", so that the strip conforms to the curvature and is constrained at both ends. That border would have to be removable in order to release the part after infusion. Or use weights or spreader clamps or similar things to hold things in place. The vacuum bag would press the veneers tightly into place but might reveal some gaps. The resin could easily flow between the gaps in the wood. That is why I'm happy to see your result showing that resin can easily creep like 5cm along fiberglass between mold and wood.

    You could also pull a deep vacuum or heat up the wood a bit. Say 50°C with a black blanket in the sun so the water boils out of the wood under vacuum. So you can put in the wood "wet" and then dry it out while pressing it in place. Would require a vacuum pump that is impervious to water vapor though. This could decrease weight and/or might increase resin uptake / bonding. It could create something more akin to heavier stabilized wood.

    With vacuum infusion you could take all the time in the world to prepare and "puzzle it out". Ideally you'd want a mostly transparent mold to see the woodwork. It would certainly be slower than foam sandwich. You could also add reinforcements, cutouts or rebates, keel, stringers and the like.

    Advantages would be that it's potentially stronger and lighter than plywood (unstressed compound curves) and cheaper than foam core (which costs an arm and a leg). And the veneer under glass could look absolutely gorgeous. Different colors translucent resin. Replace some knotholes with pennies for good luck. Sprinkle some glitter in there haha.

    Problem with this could be that the wood shrinks too much while drying. In the worst case crinkling the fiberglass. Or you have too many voids or gaps between sheets that could eat a lot of epoxy. Do you know the shrinkage rate of steamed wood? Even just 1% along 2m would be 2mm. Getting this right is the tricky part.

    This could be a potential way to build very cheap and fast in places where plywood and sandwich foam is not affordable. Even PVC foam costs and arm and a leg imho. You could even build a simple veneer making machine (a big planer with an electric motor and a stepper motor for changing height) and slice up a green log yourself.

    PS: I did suggest this idea before in this thread but got hung up on CNC and got mostly shot down. But with an easier to make mold it might be more feasible. If you have the money, you'd really want to use foam though.
     
  12. Yellowjacket
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    Yellowjacket Senior Member

    Since you are trying to make a flat surface it's easier than that, and you don't need to vacuum bag it. First cut and stain your veneer to the color desired. If you're using this outdoors you want to use a stain that is UV tolerant. Lockwood had dyes that are metallic based and are much more UV tolerant than conventional stains. Secondly as noted above, use a cloth that is treated with a wet out agent to make it wet out clear. Limit your cloth to 6 or at the most 8 ounce. More than that and you'll never get it to wet out clear. Thirdly use a UV resistant epoxy. Raka has a very reasonably priced UV resistant resin. Thirdly use a slow hardener. This will help you get the glass to wet out better and be clear. If you are going to walk on this you probably want a layer of plywood between the veneer and the foam. Even if the ply is only 1/4 of an inch thick it will be a lot stronger than just the foam If you're going to walk on this. If you look at surfboards, they typically had 2 layers of 6 oz cloth and if you walked on one with shoes you could damage the surface because the foam under it wasn't that stiff. Use a good grade of marine plywood and don't use something like Okoume (which is soft) as it will not support people walking on it without damage and delamination. You don't need to vacuum bag it. Just lay it up and lay a piece of clear heavy mylar or polyethylene-type plastic on top when you are done laying it all up. Wet the layup well, and roll the mylar on so that you squeegee out any air bubbles and you will not need to sand the surface, it will be perfect. Finally use a good exterior or marine UV resistant varnish as a top coat and replace it every few years. I've used this process to restore an old race boat and it came out beautifully.
     
  13. waikikin
    Joined: Jan 2006
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    waikikin Senior Member

    Hi JohnMarc
    Mr E is giving good advice. The stitched fabric is the clarity issue... use some couple layers of 6 oz boat/board cloth. Infusion sounds cool & techhie- bleeding edge of the game but it's not you'd be better off with a white rubber squeegee on the finish you could call it Fabric Flexible Delivery System or F.F.D.S. or invent another acronym that sounds the jazz. Lots of crap infusion jobs out & about & big bucks to fix- has it's place but not necessarily the "best" way to go.
    All the best from Jeff.
     
  14. ondarvr
    Joined: Dec 2005
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    ondarvr Senior Member

    Hand layup will yield a clearer laminate than infusion.
     

  15. Dejay
    Joined: Mar 2018
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    Location: Europe

    Dejay Junior Member

    Clearer laminate? Isn't there less voids with degassing and infusion?
     
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