Step 3: Apply a Thin Coat of Epoxy

The first step is to mix up a batch of two-part epoxy resin. This is used to seal the open foam core of the board. You can use whatever resin system you like - just mix the resin according to the directions on the bottle and make sure you measure carefully. We happen to be using West System 105 epoxy resin.

Some things to think about when mixing resin for the first time are:

  • How much resin will I be using for this step? Small batches are better then big batches since the pot life of most resins will be between 15 and 30 minutes once they are mixed.
  • Are all my project pieces in place?
  • Does this resin need to be thickened for this application? If you are going to be applying the resin on a vertical surface, or are wanting the resin to act more like a filler (like bondo) then you'll probably want to add a thickener agent, like carbosil, or fairing filler as I will refer to it in the next step.

Once things were prepped, we mixed our epoxy resin system according to the directions and applied a liberal amount of the resin with a brush onto the entire area where the inner core foam was exposed and then allowed it to dry.

It's best to lay down this primer coat of resin that will penetrate the project surface before adding in any of the thicker resins that contain fillers so that they'll have something to grab on to.
This is exactly the kind of tutorial I was looking for. Thanks so much for all the detail!<br><br>Are you still using the kiteboard?
nice instructable, ive been looking to just play around with fibreglassing but the glass is like 20bucks per square meter, for the sake of playing around, would sum of that fibreglass roof insulation work as the glass?? i know it wouldnt be anywhere near as strong but wld it be possible, i think they have additives that make it flame retardant and stuff,
The fiberglass insulation for roofs is totally different than the fiberglass cloth that you want to use. The cloth is strong because it's woven together. Fiberglass roofing insulation is just big clumps of fiberglass fibers and won't preform at all like the cloth. You could experiment, but I wouldn't hold much hope.<br/><br/><a rel="nofollow" href="http://www.shopmaninc.com/cloth.html">http://www.shopmaninc.com/cloth.html</a> among many other online retailers of fiberglass cloth has lots of different weaves for between $6 and $7 a yard. $20/sq meter sounds a bit pricey.<br/><br/>Good luck,<br/>Noah<br/><br/>
Thanks for the good info provided. I was "taught" by a very experienced 73 year old guy who offered to repair my damaged boat. Many of your details mirror his words and I have enjoyed reading the clearly explained steps. Working with fibre glass and resins is a "life skill" that is under-rated in my opinion.
1, painters mixing cups work well just thro them out in the end 2, that fiber glass u were using looked really thing like material like 3, woven is used for flat and choped for curves 4, ripping choped works better then cutting uneven means it bonds together better 5, another thing is waiting times between resins can cure for days 6, i hope u sanded ur start proget back far enough to take off the clear coat other wise the bond wouldnt be to strong 7, i dont no y u didnt just lay the glass first normaly its material resin let dry fiberglass body filler primer paint ( but thats from scratch ) in this u wouldnt need material as u have some thing to work off if any one is really interested in fiberglassing check out www.fiberglassforums.com its a great forum and so many pros that could help u out
wow this is great! aha i've always wondered how people fiberglass stuff. i thogtu it was some melted plastic that you mold haha
Brilliant tutorial. I know quite a few people who this would help greatly.
Really cool Instructable, kiteboarding looks fun. I wish I could try it someday...
Another thing to note with polyester/epoxy resin (in addition to what dan mentioned).... Chopped glass mat may not be compatible with epoxy resin because of the binder used to hold the strands together (contact mfr to see if their mat is compatible). Not a problem for woven composites as they are held together by stitching. I agree with dan wrt epoxy versus polyester. If you're working on smaller projects like this, epoxy is the way to go and a gallon will last a long long time. For larger projects (the HPV tooling, boat hulls, etc.) - polyester is choice. Boat making primarily uses polyester resin (and they go through a boatload of it :p). Tooling for the HPV project used 10 gallons of polyester resin. <-- polyester is $135 per 5 gallons versus Epoxy at $245 per 5 gallons.
Can you make a metal wire frame and use fiberglass to make it into a 3D form?
polyester resin is quite toxic - both to touch, and it releases considerable amounts of toxic styrene fumes (OSHA's permissible exposure limit is 100 parts per million).<br/><br/>I recommend always using epoxy, never polyester. the cost difference is negligible for most projects. A gallon of polyester resin is about $30, a gallon of epoxy is about $45. Here is a good source for low cost epoxy: <a rel="nofollow" href="http://www.uscomposites.com/epoxy.html">http://www.uscomposites.com/epoxy.html</a><br/>a gallon will last forever! you could build a car with that much. for a kiteboard you might spend an extra $2 to use epoxy, but you won't have to worry about all the toxic fumes, plus the epoxy is a lot stronger.<br/><br/>There is only one property of polyester resin which is useful - it does not yellow like epoxy does under long-term sunlight exposure. if you want your epoxy not to yellow, you need to either paint it or coat it with a clear UV protective coating (which is commonly available since its a common problem).<br/>

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