Gluing Canvas to 1/8 " Mahogany Plywood

Discussion in 'Boat Design' started by Martinup, Jun 8, 2012.

  1. Martinup
    Joined: Jun 2012
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    Location: Vancouver, BC

    Martinup New Member

    Hi everyone:

    Before I start my apology as I know this is boat design forum But I need the experts’ advice on attaching Canvas to a complex compound roof? I am a wood worker of many years and look forward to chatting with people here.

    Attached are pictures of my very Curvaceous Trailer build.

    So far I have:
    1) purchased painter's drop cloths 10 once heavy tan colored
    2) washed them in the washing machine . . . Hot water/ with soap and lots of bleach
    3) Dried them in the dryer to shrink them
    4) torn all the seamed edges off etc.

    Questions:

    1) Do I need to rot or water proof the canvas in my application? If so . . . with what?

    2) Can I simply use Titebond 2 or 3 to my rounded surfaces and over lap slightly?

    3) I am trying to not use expensive epoxy or fiber glass, resins etc, hence this route. I am not excited about the smell and toxic stuff. I have done enough spray booth work etc.

    Once this is done I would like to fill the weave with??? More glue or good quality marine paint??? and somehow produce an auto body show and shine finish.

    4) I will apply neoprene moldings to cover any critical seams ie roof meets wall surface to shed the water similar to a gunnels and kind of like a drip rail. By the way the walls will be clad with stainless steel.

    Thanks all for your help,

    Martin

    Vancouver, BC
     

    Attached Files:

  2. hoytedow
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    hoytedow Wood Butcher

    Welcome to the forum, Martinup. Nice trailer!

    Since you don't want to use epoxy, perhaps you should use the same technique used to cover a canoe in canvas, the technique used before the invention of epoxy.

    Click on this link:
    http://www.boatdesign.net/forums/wo...n/restoring-classical-canvas-canoe-24071.html : "No glue needed. Built one 40 years ago. Simply stretch the canvas over the hull and fasten to sheer strake with battens."
     
  3. Martinup
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    Martinup New Member

    Thank you Hoytedow:

    I scanned through some of the links you refered me to. I know there must be all the answers in this forum . . . It is know where to find them.

    Typically with canoes I gather you can use one long piece and stretch it taught from both ends. My trailer is 7 feet wide plus the 17" radiuses and 25' long. The 3 foot wide skylight runs down the centre. It will be difficult to stretch the material and hold it while the glue dried. I will as it is be cutting and seaming to make sure ther are no wrinkles.

    If I were to use Epoxy resin do you have a rough cost . . . How many 5 gallon buckets would it take? cure time etc etc?

    I do not want to have this fail on me in a few short years. I spent a long week cutting fiting and gluing the 1/8" mahogany plywood to my frame work. Sorry the pictures did't come in bigger so you could see better detail.

    I then used plastic wood filler to fill the 3000 staples.

    Thanks everyone for your suggestions.

    Martin Merkli
     
  4. hoytedow
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    hoytedow Wood Butcher

    Don't glue it. Two gallons of epoxy should do the whole trailer outside even if the wood is porous. I am using West System 105 1.2 gallons mixed will do approximately 400 square feet. Google product specifications.

    I spent 177 dollars US for 1.2 gallons resin/hardener with pumps and spreaders.
    http://www.westsystem.com/ss/105-epoxy-resin/
     

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  5. hoytedow
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    Location: North of Cuba

    hoytedow Wood Butcher

  6. Martinup
    Joined: Jun 2012
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    Martinup New Member

    Wow that is reasonable and I've read good things about west system. Does epoxy eat IKO therm Roof insulation , R-15 on 2 1/2" thick, ( yellow color and really soft, " I cut away the black tar paper to expose the yellow core . . . to sand it Super Easy ) ? I this used on the, Trolley Top to form light weight and easy to carve curves right along the Skylight. The yellow ,' I THINK IT IS URETHANE BASED", I will confirm this. Also do I coat the plywood first then let it dry. . . . Then sand . . . add a second coat and lay in the canvas squigey it smooth adding more epoxy resin . . . brush it out or roller it even? I am really stoked that this will take so little epoxy / resin catalyst etc. Even if it takes around one Five gallon buck thats OK. An approximate all in rough cost would be helpfull?
    Thanks,

    Martin
     

    Attached Files:

  7. hoytedow
    Joined: Sep 2009
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    hoytedow Wood Butcher

    Epoxy should not eat any plastic. Polyester resin will eat styrofoam. Your insulation is one of the cyanates and should be safe from epoxy. Sand the surface smooth then lay on the cloth dry. fold the cloth back halfway and wet the wood. Pull the cloth over the wet area and wet it out, smoothing wrinkles and high spots as you go. Then fold the other half back and wet the wood on the other side. Lay the cloth back down on the wet wood and wet it out, smoothing wrinkles as you go, as before. Let the epoxy harden before proceeding.

    Practice on a small test piece first!
     
  8. hoytedow
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    hoytedow Wood Butcher

    Don't mix more than you can work with within the pot life of the mixture.
     
  9. Martinup
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    Martinup New Member

    I am happily off to the store to get my epoxy thanks much for the info and yes I will bring a piece of the instlation and test it . I love it when I can read the letters from next door, Ha ha.

    I will post some pics as I get it done . . . . A bright canarey Yellow should jump out at you for by base coat color. Rainbows and buymble bee ( black and yellow 0 are what i'm thinking :cool: :idea:

    Martin Merkli
     
  10. Jeremy Harris
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    Jeremy Harris Senior Member

    I've never yet found a foam that epoxy resin attacks, and have just built a boat using underfloor insulation foam clad both sides with epoxy glass. Using epoxy/glass or perhaps even the canvas and epoxy should give you a very tough covering. Only thing to watch is that you will need to paint it with a UV protective coating, as epoxy tends to degrade in sunlight.
     

  11. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Instead of buying West System, which is good stuff, you should consider Marinepoxy at Bateau.com or one of the choices over at epoxyproducts.com. You'll spend half as much for goo that works just as well.

    I wouldn't use epoxy on your canvas covering. I would use the traditional method of alkyd paint or the newer method of a PVA, such as TiteBond III (not TiteBond II). The traditional paint method will let things move under it and the canvas can be easily removed when it's time to replace it. PVA's offer the same thing, but protect the canvas and underlying surface much better, so it lasts longer. It's a little harder to remove when this time comes, but nothing compared to if epoxied down.

    If you want to use epoxy, then the substrate at the very least needs to be well coated first (10 mils minimum) then the canvas. This material (canvas) isn't very durable, so I'd switch to Xynole, as the first choice and Dynel as the second. These will offer real serious abrasion protection (many times that of canvas or regular 'glass cloth) and will water proof the surface.

    Before buying more products, you should do some more research on deck coverings and related techniques. Log onto both westsystem.com and systemthree.com and download their free user's guides. These will nurse you through the basic techniques and product types and leave you much better armed, to tackle this portion of your interesting project. The reasons I say this are you've made a few mistakes in regard to previous materials purchases and treatments. For example, washing and bleaching the canvas has removed it's shrinkage factor, which is how you get it to look tight, once applied to the substrate. Typically, you'll apply and stretch out the canvas as best as you can, then wet it out with hot water or steam, knowing it'll shrink and tighten up, removing wrinkles, etc. Second is the weight of fabric selected. It'll work, but require huge amounts of paint, PVA or epoxy to full wet out, so before you buy anything else, my recommendation is to do some more research about deck covering types, techniques, tips, tricks, material choices, etc.
     
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