Plywood made with epoxy.

Discussion in 'Materials' started by Canracer, Jan 23, 2015.

  1. Canracer
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    Canracer Senior Member

    Why is quality plywood made with glue, and not with epoxy?
     
  2. SukiSolo
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    SukiSolo Senior Member

    Why use a more expensive glue that does nothing much extra compared to the existing ones? You can make your own ply using epoxy if you wish, you will need access to a good veneer merchant though.

    Resourcinols, fomaldehydes, etc etc are all perfectly good glue systems up to the job. Of course you can use thes too as adhesives for your own ply. Main difference is the gap filling ability and increased cohesive strength of epoxy. In controlled conditions with known stock, these are not issues. Also processing time is important and some of these other adhesives can be cycled faster.

    However note the ply grade if using for marine and the old BS1088 is still the best standard. I've run into a lot of cheap exterior WBP which has peeled in months so someone is telling porkys'.....;)
     
  3. Canracer
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    Canracer Senior Member

    I'm sure that BS1088 plywood is good, but anyone who buys that stuff is probably using epoxy for the rest of the project.
     
  4. DCockey
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    DCockey Senior Member

    Cost is probably the major reason epoxy is not used to make plywood in volume. Not just the cost of the epoxy but also the total cost of manufacturing including cycle time. Also, my guess is the adhesives used in marine plywood have better high temperature properties than most epoxies.

    Why would plywood made with epoxy be an if the boat builder is using epoxy? I've never heard of any incompatibility between epoxy and the cured adhesives used in plywood.
     
  5. frank smith
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    frank smith Senior Member

    Epoxy is not the best glue for all things. Resorcinol is better in many cases. Given that ply wood is produced in a controlled environment, and glued under heat and pressure, epoxy is not the glue one would want.
     
  6. Steve W
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    Steve W Senior Member

    Agreed, there are many superior adhesives but they are more specialized, where epoxy shines is as a one size fits all material. It would be inferior for plywood production imho.
     
  7. Canracer
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    Canracer Senior Member


    I don't follow this question.
     
  8. DCockey
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    DCockey Senior Member

    Post above corrected:

     
  9. PAR
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    PAR Yacht Designer/Builder

    The primary reasons epoxy isn't used in plywood are cost and cure time. Heat activated adhesives can cook and get cut quickly, while still waiting on the epoxy to gel up. Then the big motivator, cost, which will make the number crunchers at the plant crap themselves, looking for less costly alternatives.
     
  10. Mr Efficiency
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    Mr Efficiency Senior Member

    haha, ain't that the truth, cost is king.
     
  11. latestarter
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    latestarter Senior Member

    You can not consider the glue in isolation, it is attached to the plies on their face so if trying to pull them apart you are creating tension at right angles to the grain, the direction where the wood is weakest.

    Using a super strength adhesive instead of an adequate one is not gaining anything, the failure will still be in the wood.
     
  12. PAR
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    PAR Yacht Designer/Builder

    This is irrelevant, if the adhesive is tougher than the wood fibers along their weakest axis. They've long had adhesives that exceeded this need, in plywood.
     
  13. Canracer
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    Canracer Senior Member

    So I guess that ply made with epoxy would be a case of over-engineering. And a waste of good epoxy.
     
  14. Steve W
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    Steve W Senior Member

    Yes, most likely an expensive way to produce inferior marine plywood panel. Epoxy is not the be all end all adhesive, there are other adhesives that are better for some purposes such as making plywood, where epoxy really shines is its ability to do a lot of things pretty well. Epoxy has been marketed so well that newbies tend to think its a miracle material.

    Steve.
     

  15. DCockey
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    DCockey Senior Member

    Not sure about "over-engineering" because the properties of epoxy are not better for manufacturing plywood than the adhesives currently used in quality exterior and marine plywood. Epoxy is not the ultimate wood adhesive. There is no single ultimate adhesive for all wood bonding applications.

    One major advantage of epoxy in some applications is that epoxy does not require a tight joint and can fill joints. That ability is not needed in manufacturing plywood.

    Information about adhesives used in manufacturing plywood is on pp 65-69 of Adhesive Bonding of Wood Technical Bulletin No 152, USDA Forest Service http://www.woodcenter.org/docs/tb1512.pdf
     
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