Epoxy resin on object with multiple sides corners

Discussion in 'Boatbuilding' started by aaronhl, Jul 10, 2013.

  1. aaronhl
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    aaronhl Senior Member

    Looking for tips or tricks for a smooth epoxy finish over these model boat sponsons. The wood is thin plywood, but the multiple sides and angles makes it difficult to epoxy in more than 3 settings without drips, runs or blotches. I plan on making many of these so need an easy way to apply the epoxy. I have been scraping them with a card, leaving only rough patches and blotches everywhere from the gloves touching. The pictures show a nice finish but it's not the case..

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  2. HakimKlunker
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    HakimKlunker Andreas der Juengere

    You will not get away with one single application only. The wood fibres on the surface will sort of stand up.
    Think about this: One first coat with EP and thinner (only if epoxy strength reduction can be tolerated). Let it cure and sand slightly until all surface is dull.
    Apply more coats with warm resin. Warm: it flows easier and cures faster.
    Make sure that dust has no chance.
    All these edges are tricky: The coating there will usually be thinner than on the bigger surfaces.
    Out of interest: What is your construction meant to be?
     
  3. PAR
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    PAR Yacht Designer/Builder

    Apply the first coats (raw wood only) with a plastic applicator. get the surface good and wet, then scrape away excess, moving it to dry areas as you go. The result on this coat should look dullish and no pooling anywhere. This will seal the wood and not outgas (bubbles).

    Subsequent coats will need to be thin. A brush is the worst tool, as it makes puddles with feathered edges, so again use an edge tool, but a squeegee will give better results. You'll need a few different sizes and working from top to bottom helps.

    The roll and tip method can help, but you'll need an especially fine nap roller. Make sure you roll it out good and thin, then lightly tip off with a dry foam brush, SLOWLY. Wipe the brush after each pass so it stays relatively dry. This is tedious, but works with some practice.

    Spraying would produce the best result, so if you have a gravity feed gun and a few tips, experiment with which puts the best coat down. A light coat will stay put on vertical surfaces, but it's really easy to bulk up too fast and get sags. This is the ticket for any type of production run. If you must, cut the epoxy with denatured alcohol up to 10%, to remove stipple. The cut is only to remove spray stipple, not to get it to go through the gun. Tip selection is what gets it through the gun. On something like that, I'd be inclined to use an airbrush instead of a touchup gun.
     
  4. MoePorter
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    MoePorter Junior Member

    Follow the excellent advice from Par & HakimKlunker BUT precoat the panels before cutting & assembly - efficient practice is to epoxy coat to desired finish whole sheets of ply. Much easier to use larger, quicker sanders for a more even surface than trying to sand those little bits after assembly. You still have to touch up the exposed edges left after cutting but that's all. Also sharpens the thinking on how to get maximum yield out of your expensively coated ply sheets...Moe
     
  5. PAR
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    PAR Yacht Designer/Builder

    Good catch Moe and a common method of controlling quality.
     
  6. aaronhl
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    aaronhl Senior Member

    Wow thanks for the help everyone, I will be coating the sheets before cutting the pieces. I think that is a great idea!!

    How would you heat epoxy? Where can I get a fine nap roller?
     
  7. HakimKlunker
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    HakimKlunker Andreas der Juengere

    Welcome :).
    Place a can in a warm water bath and get to your desired temperature.
    Only then mix. Otherwise you will have coated the cans only ;)
    You will need to experiment a little to find YOUR convenient temperature.
     
  8. PAR
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    PAR Yacht Designer/Builder

    A micro wave works better, as the resin is heated quickly and you don't lose so much pot life time, while waiting for the water to transfer it's heat. 100 degrees is a good start, but again this is only necessary on raw wood coats.

    A roller is a good way to apply epoxy on large surfaces, as it lays it down in a uniformly even coat. Rollers are wasteful to a degree, as you can never get it all out. I prefer squeegees and plastic applicators, which don't waste anything. Rollers can be had at paint supply stores and through online retailers. Also the major epoxy formulators sell rebadged rollers. Buy a few, then read inside the roller to see what they've sold you and buy direct, to save some money.
     
  9. LP
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    LP Flying Boatman

    I use an old electric space heater (warm air, not infrared) in front of the resin bottle for about 30-60 minutes before mixing. Once the resin is dispensed, I hold the mixing container in front of the heater while mixing. Makes for some nice thin and runny goo.

    Good Luck.
     
  10. PAR
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    PAR Yacht Designer/Builder

    That's one way LP and some use a 100 watt incandescent bulb, in a box, where they store their goo, which also works. I'm in Florida, so my goo is usually pretty thin anyway, but I'll heat up, both parts (separately) in the microwave for 10 seconds and skip all the bother. Of course, you'll need to do this when the one that must be obeyed isn't home, or you'll just end up buying her a new microwave. In fact, this is a plan that most builders have to develop, to get some of the tools they need. A flour sifter is a handy thing, but if she catches you with her mother's hand me down sifter, you're screwed, so just get over the idea of sneaking it and buy her a few new tools for the kitchen. I have a 50 amp electric stove, I use for post curing, a blender, a vegetable chopper, a microwave, the flour sifter, turkey baster and assorted other stuff, If been caught with and had to replace. Get over it, she will once she gets to go shopping for a new one. One last tip, buy her the good stuff, as you never know when the piece of 30 year old, hand me down crap, you stole out of her kitchen, will break and you'll need to work up a new round of "procurement" procedures.
     
  11. aaronhl
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    aaronhl Senior Member

    Nice tips guys!!!

    Here is what I am building. I am going to use your tips even on the center piece. Just to give you an idea 41" long and about 5hp

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  12. HakimKlunker
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    HakimKlunker Andreas der Juengere

    I wanted to mention it, when I saw that you already did.

    Try this: Offer some help in the kitchen: Bread slicing? Bring your hand saw. Open a bottle of wine? Screw Driver, screw and pliers. Open a can? Side angle grinder. And so on.
    Later you will be able to point out how much the workshop contributes to the kitchen - so that the few minutes with the fruit blender REALLY cannot be soooo significant.
    (As a side effect, it is likely that you become less involved in kitchen activities :D)
     
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