plywood, laminating resin

Discussion in 'Fiberglass and Composite Boat Building' started by Cjmac, Jun 10, 2018.

  1. Cjmac
    Joined: Mar 2018
    Posts: 32
    Likes: 0, Points: 6
    Location: Pensacola

    Cjmac Junior Member

    so as a learning curve I have learned laminating will cure to a hard finish and not be sticky / tacky after sitting for 24 hours or so, WHY ? thought is was supposed to stay tacky for future layup ?... so do I need to sand it if it cures to a hard non tacky finish if I'm going to gelcoat It later ?? if so I mine as well just buy finishing resin in the future right ? . .. the biggest thing I wonder about is what kind of plywood or wood is not good for glassing over with with polly . I'm about to replace the floor in this little river boat I was given . so what plywood to use...sorry for all the questions just trying to ask everything at once ..thanks , cj
     
  2. fallguy
    Joined: Dec 2016
    Posts: 1,235
    Likes: 47, Points: 48, Legacy Rep: 10
    Location: usa

    fallguy Senior Member

    I always sand after the epoxy has set as a rule. Only no sanding if no set; other epoxy vendors will suggest longer times. I sand.

    Wash if blush or waxy with warm water n soap.

    I'd avoid poly over ply as poly is not waterproof.

    Small boat floors 1/2" to 5/8".

    Larger boats 3/4".
     
  3. Mr Efficiency
    Joined: Oct 2010
    Posts: 6,758
    Likes: 178, Points: 63, Legacy Rep: 702
    Location: Australia

    Mr Efficiency Senior Member

    Member ondarvr is your man, for questions pertaining to resins.
     
    fallguy likes this.
  4. Blueknarr
    Joined: Aug 2017
    Posts: 333
    Likes: 32, Points: 28
    Location: Colorado

    Blueknarr Senior Member

    Laminating polyester resin is supposed to remain tacky to provide a chemical bond with the next layer. Works well when the layers are added quickly. It should stay open for a few days to a week, not indefinitely. Dust contamination alone would interfere after that. Hight catalyzation or temperature shortens open time. Personally, I drag a piece od 36 grit over the surface just to insure there's nothing sticking up that might interfere with the next layer.

    I have 25 years of experience as an industrial painter. I am now hardwired against add wax into resins. Many others may successfully use wax, but it just rubs me the wrong way.

    Polyester wood bonds have a notoriously bad reputation. Mostly due to poor technique. Typically production workers drape cloth over dry wood. The wood absorbs some of the resin resulting in a starved bond. Pre-coating, and allowing to gel, largely eliminates the problem.
     
    d. right likes this.
  5. Mr Efficiency
    Joined: Oct 2010
    Posts: 6,758
    Likes: 178, Points: 63, Legacy Rep: 702
    Location: Australia

    Mr Efficiency Senior Member

    polyester resins as commonly sold contain thickening pigments or agents, that make it useable on vertical or overhead surfaces, without sagging, one presumes, maybe wrongly, that a thin resin not loaded up with such agents would migrate into the wood surface better, and improve the bond, and then the laminating resin be used, but I would defer to people such as ondarvr on that one.
     
  6. Cjmac
    Joined: Mar 2018
    Posts: 32
    Likes: 0, Points: 6
    Location: Pensacola

    Cjmac Junior Member

    Im thinking theres wax in this polly resin due to the fact it cured so hard . I mean it was about 85 outside but i catalyzed 1.5 % . Im about ready to just say the heck with poly resin only reason i like it is i can gelcoat it and thought it would be faster for makeing small projects. Iv done small repairs with finishing resin amd gelcoat before and turned out great . But thay where small holes and such . Yall think i should try and order some resin from a supplier? Maby the local boat yard stuff isn't that good ? Another reason i find poly resin good is it works good with csm . Epoxy dont .
     
  7. Cjmac
    Joined: Mar 2018
    Posts: 32
    Likes: 0, Points: 6
    Location: Pensacola

    Cjmac Junior Member

    Im good with epoxy . Just have to use cloth , and fair with a mix . Just hate the long curing times
     
  8. ondarvr
    Joined: Dec 2005
    Posts: 1,778
    Likes: 83, Points: 48, Legacy Rep: 506
    Location: Monroe WA

    ondarvr Senior Member

    You can use various types of plywood, but for a low cost durable product use exterior grade Fir. You can pay more and get better stuff, but on a small cheap boat it may not pay off, do a good job and the ply will last a long time.

    The resin may or may not have wax in it, even resins with no wax can appear to be tack free in less than 24 hours. The bond can still be very good though. Just say "no" to wax if possible, only add it yourself when needed.

    As long as you apply another layer or coat while it's still tacky the wax isn't a problem.
     
  9. Cjmac
    Joined: Mar 2018
    Posts: 32
    Likes: 0, Points: 6
    Location: Pensacola

    Cjmac Junior Member

    Expensive wood would be a waste on this. Boat is kept inside on trailer . Just use it for brim fishing. I might need new resin. This stuff is about 6 or months old . Gelcoat seems ok last time i used it. People say gelcoat will last a while . Dont know
     
  10. Cjmac
    Joined: Mar 2018
    Posts: 32
    Likes: 0, Points: 6
    Location: Pensacola

    Cjmac Junior Member

    I can get a gallon with mekp for about 55$ thay give you 2 oz of wax for free . Its from fiberglass site .com has lot of good reviews
     
  11. Sparky568
    Joined: Jan 2017
    Posts: 71
    Likes: 2, Points: 8, Legacy Rep: 10
    Location: Northeast USA

    Sparky568 Junior Member

    Hot coat the wood before applying laminate and it will hold up fine. Gelcoat, as long as it doesn't contain wax should last as long as any resin. I typically buy resin in 5 gallon pails. If I am say half way or less into the pail and know I won't be using it for a few weeks or even months I transfer remaing resin to smaller containers to limit air exposure.

    I also mix well anything that has been siting for a day.
     
  12. Michael Simmons II
    Joined: Jun 2018
    Posts: 2
    Likes: 0, Points: 1
    Location: West Melbourne Fl

    Michael Simmons II New Member

    Rule of thumb that I use, is after layup, 3 day no prep. If it is in a clean inviroment (inside out of the elements), within three days you shouldn’t have any prep. It will still chemically bond.
     

  13. pauloman
    Joined: Jun 2010
    Posts: 265
    Likes: 10, Points: 18, Legacy Rep: 151
    Location: New Hampshire

    pauloman Epoxy Vendor

    lots of really strange ideas here. call me to discuss - paul at progressive epoxy polymers inc - 603 435 7199
     
Loading...
Similar Threads
  1. gary1
    Replies:
    4
    Views:
    6,539
  2. CBTerry
    Replies:
    13
    Views:
    477
  3. polarhiker
    Replies:
    12
    Views:
    712
  4. Clive Barry
    Replies:
    2
    Views:
    661
  5. ImaginaryNumber
    Replies:
    26
    Views:
    3,035
  6. mtumut
    Replies:
    4
    Views:
    867
  7. Norado
    Replies:
    5
    Views:
    1,710
  8. pavel915
    Replies:
    6
    Views:
    3,604
  9. leaky
    Replies:
    16
    Views:
    12,741
  10. Lurch723
    Replies:
    14
    Views:
    2,759
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.