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 Post subject: What is hot coating exactly?
PostPosted: Thu Jun 17, 2010 6:25 pm 
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What is hot coating exactly and why is it done?


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 Post subject: Re: What is hot coating exactly?
PostPosted: Thu Jun 17, 2010 6:38 pm 
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I did end up finding this post:
viewtopic.php?f=107&t=2318507&hilit=hot+coating

To keep the board light, what would be recommended to fill the glass structure if one does just one layer of glass/epoxy coating hand layup?

What if I want it clear?

What if I don't care but want light as possible?

What if quick and dirty? (Maybe just a spar polyurethane)?


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 Post subject: Re: What is hot coating exactly?
PostPosted: Thu Jun 17, 2010 10:15 pm 
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You pretty much need to do the hot coat to fill the weave. You end up sanding most of it back off anyway.

With poly you use sanding resin (resin + a little wax) and with epoxy you just use straight epoxy.

It will be clear.

If you don't care about light you just don't have to be as aggressive in sanding it back.

Quick and dirty has it's place, but spar poly isn't much cheaper than poly resin and won't last nearly as long. Adding glass gives the board a better flex and makes it waterproof.

It's actually really easy, just practice on a small piece of scrap plywood and laminate a layer of glass on it, let it cure, then put a hotcoat on it, let it cure then sand it back smooth. You'll see what a nice finish it gives and how it stiffens and strengthens the wood.

Here's a pretty detailed video on doing a hotcoat on a surfboard:


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 Post subject: Re: What is hot coating exactly?
PostPosted: Fri Jun 18, 2010 1:03 pm 
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Thank you so far so good. How about overlapping the top and bottom layer around the edge? I know some use ABS rails so they don't have to wrap. If I don't want to use ABS rails, how would I go about?

With surf and windsurf board I think one starts with the bottom first and wraps the glass around the bottom edge as much as possible, then the top will overlap the wrapped part and glass gets cut off at the edge of the bottom layer.

So, how do I do it with a thin kiteboard?


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 Post subject: Re: What is hot coating exactly?
PostPosted: Fri Jun 18, 2010 3:52 pm 
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"So, how do I do it with a thin kiteboard?"

That's the problem. The glass won't wrap around the really small edge radius without causing lots of problems and headaches. Surfboards have nice rounded radius rails (mostly). All kite/wake/snow boards have really thin edges and none of them wrap the glass around the rail. They all use some sort of rail material to seperate the deck and bottom and to provide a more impact resistant edge.

Besides ABS, the next easiest thing is to pour thickened resin (resin + microballoons or resin + chopped strand) around the edge to make a solid resin rail bead. I'll try and dig up some pictures that illustrate the concept.


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 Post subject: Re: What is hot coating exactly?
PostPosted: Fri Jun 18, 2010 6:24 pm 
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Love to see some pictures of the rail building process.


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 Post subject: Re: What is hot coating exactly?
PostPosted: Sat Jun 19, 2010 4:34 pm 
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Location: Iv.G.-Slovenia
daspi, I know, you think there is much more work if you use ABS or pured epoxy rails, I thought that's true too, and did my first 4 boards with overleaping the edge.
But like lawless mentioned it is almost imposible, to do this perfect and by overleaping like in surfboard production, you will make the edges much more stiffer and that you don't want.
So there's another variant I did. I laminated the top first and overleaped just the edge and not the bottom (and it would be imposible too, because the board was on the rocker table). So, as you can see from the picture there is from perfect bond to the edge to no bond at all, so you have to fill the gap with epoxy and wrap the board with tape, forcing the coured laminate to the edge and after couring and removing the tape there are still some gaps, you have to fill with epoxy. After this long proces you just laminate the bottom straight.
Image
The look of the edge from the upper side:
Image
You could probably do this better, if you laminate w/o vacum bagging and no rocker table, but that way it is harder to do the surface good, so I don't realy think about hand laminating. And there is a big probability, that sooner or later you will hit a rock or drop the board on the edge and damage the laminate and the core will be exposed to the water.

So this is how I do it now!!!:- pured epoxy rails
I cut a pattern with finished board shape and seal the edge with a tape, so the epoxy won't bond to it, I cut the bottom core layer smaller (1 cm arround), than mark the core outline to a stiff board and tape the line with two-sided tape (why? later!)
I position the pattern and the core to get the same gap all around and than use a tape (main reason: epoxy won't force out) to get them together.
Image
Than you position this on the stiff board you prepared earlyer, tape facing down.
Explanation of the two sided tape:
Because the tape, you used to get the pattern and core together is wrinkled, you straighten it out by sticking it to the two sided tape.
Than screw or weight down the pattern and the core.
I fill the rail gap with choped strands, mix the epoxy with microbaloons and some cotton flakes (for epoxy to harden faster) and pure it in with injection, because it is easyer to dose, or there will be a lot of mess (and later sanding too). It is god if the pattern is a litle bit thicker than the core.

I hope you understand my discription of this process.

BR, Zob


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 Post subject: Re: What is hot coating exactly?
PostPosted: Tue Apr 19, 2011 9:25 am 
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Location: Denmark, Frederiksværk
Hi zob

How did you make that rail? I'm building a carbon board and want to make a poured epoxy rail for it. When I cut out the woodcore I'll save the "left over wood" and use it as a mould, like I think I can see, you did as well. I'll then cut of 0,5mm of the board and then fill the gab with epoxy. So I got that covered. But afterwards what then? Can I just cut of the rest of the carbon and sand it down to make a smooth rail?How did you make that rail? I'm building a carcon board and want to make a poured epoxy rail for it. When I cut out the woodcore I'll save the "left over wood" and use it as a mould. I'll then cut of 0,5mm of the board and then fill the gab with epoxy. So I got that covered. But afterwards what then? Can I just cut of the rest of the carbon and sand it down to make a smooth rail?


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