Austin Crane

Vacuum Resin Infusion of a Kayak

Here is how I built a boat using vacuum resin infusion with some tips.

Get a mold. Maybe I’ll do another post on building molds.

The mold is waxed and ready (not shown). I run the seal tape around the flange that the bag will adhere to later. I also put some painters tape over that so any work I’m doing between this point and the bag seal, will not affect the seal tape.  This is a new mold, so I’ll also apply pva release film before I do my cosmetic layer.

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I’ve applied the cosmetic coat a number of ways. I’ve layed 2oz glass, hand layed up with a pigment rolled on with a paint roller to saturate the cloth. And I’ve done none at all. I guess this is where you get creative in how you want to construct your part and how you want it to look. The method in the picture is using normal auto body paint with an activator and applied with a auto body spray gun.

I don’t have a picture, but for this boat, I used a paint roller with 15 pumps of resin to saturate a 2oz layer of eGlass and let that cure before I continued with the steps below.

Next Step: add your layers…

This is what I call a, leftover boat. All made from scrap cloth from previous projects. It always looks prettier to use whole, continuous sheets of the cloth you’re using, but unless you’re making airplane wings, or trying to shed ounces of weight and keep strength, I don’t see the point. It’s a boat, you’re going to hit rocks and you’re going to have to patch. Plus, this is a lot cheaper.

In between layers, I use a spray adhesive to keep the layers down and organized. – Super 77 is nice.

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This boat was:

  • 1 layer 2 oz glass
  • 1 layer 10 oz glass
  • 1 layer 5 oz kevlar
  • 1 layer 1/4 foam core – diviny cell
  • 1 layer 5 oz kevlar
  • (and some extra scraps in high impact areas)

After you get your layup like you want , add the peel ply.

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Also not shown is the green flow resin mesh put on after the peel ply.

Tip: try to get the green flow to end about an inch to a half inch before your flange. Resin moves faster over green flow and slows down when there is no green flow. What this trick does is allows the vacuum to focus on other areas in your part that haven’t filled with resin. You’ll know what I mean if your resin finds your outlet hose before it has had a change to fill the rest of the part. You don’t want that to happen.

Here the bag is on and ready for a vacuum test. Pleating, adding folds to your bag so it can reach every corner of your part, is an art form. The deeper your part, the more pleats you’ll need. There are some stretchier bags out there that will allow for a margin of error. “Stretchlon”, I think? Or just learn to pleat.

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Here the bag is sucked down and ready to find leaks. Tip: run a long hose to your vacuum so you can get it out of the room. Hard to hear leaks with a vacuum pump roaring in your ears.

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More Tips: Notice the spiral tubing running the perimeter of the flange. This connects to the outlet hose that goes to my resin trap and then to the pump. This is far from any fabric of the part. Earlier, I mentioned that resin flows great over resin flow mesh, then slower over just plain fabric and finally even slower when there is nothing and it’s just bag on mold. It almost acts like a dam. So by putting the spiral outlet tubing away from any fabric, the part will full infuse with resin before finding its way to the outlet leaving absolutely no dry spots in your part. Also having the tubing go around the whole part has made my infusion experiences not only easy, but predictable. I also drape my feeder spiral tubing hose down the middle in an “S” shape with the general idea that there should be about 12″ from the hose to where you want the resin to end up.

Fully infused, clamp off your hose before the resin runs out so you don’t have a gigantic air bubble dive into your part. Resin will continue to move somewhat around the perimeter finding dry cloth.

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Things I used:

Pump: Robinair 15500 VacuMaster 5 CFM Vacuum Pump
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Resin Trap: Homemade. Here’s how I did it.  

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Resin: AdTech 820 – While this resin doesn’t require a post cure, I don’t like to work with it under 70 degrees and like to heat my small shop up as hot as I can get it while it’s curing.