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Monday, August 25, 2014

Kingfisher Drift Boat Build - Flow Coating Epoxy

I've been working on the side panels for the "Kingfisher. The process so far has gone sort of like this;

Steps So Far

(1) Scarf the sheets together
(2) Cut out the side panels to the pattern or dimensions
(3) Sand the scarf joints flat with a 1/2 sheet sander or random orbital sander
(4) Sand the the outside of both sides panels with 100 grit, 120 grit and finish with 160 grit
(5) Vacuum of the surface of the exterior side panels
(6) Cut the fiberglass mesh to size,
(7) Use a dry brush to smooth out the flberglass mesh on the panels being careful not to stretch it too much
(8) Bed the fiberglass with epoxy using a squeegee and natural bristle brush
(9) Let the epoxy set until tacky like the sticky side of duct tape.
(10) Flow Coat epoxy over the fiberglass mesh to fill the epoxy pores.

So this is the stage I'm at. I'm going to back track a bit and talk about epoxying down the fiberglass mesh first. This process is a little bit like you have enough information to be dangerous. It's like you think you've got it all figured out and then you start and realize you're sort of winging it.

The fiberglass mesh is just laying on top of the side panels dry. The first coat of epoxy will be poured onto the fiberglass mesh. I mixed up about 12 ounces of epoxy to start spreading it with a squeegee and that went pretty smoothly. Spreading it with a squeegee was pretty intuitive. You spread it from the center towards the sides and edges, smoothing it as you go and being careful not to stretch out the fiberglass mesh. They call it a "modified waitress wiping motion". When I got done the only problem I had is that I had some wrinkles at the edges and a few small, quarter sized areas where the glass floated up. I think this is par for course.

I then waited until the sheet tacked up and then did the first flow coat. This second coat of epoxy essentially fills the rest of the fiberglass mesh so you can then sand it once it dries without digging into the glass. I mixed up a batch of epoxy about 9 ounces and got started.

Flow Coating

  • Mix up about 9 to 12 ounces of epoxy. Mix it for 2 to 3 minutes.
  • Get your epoxy pallet ready, I like plastic plates on top of a scrap piece of plywood.
  • Get your tools, 3/16" nap foam roller and a 2" disposable bristle brush
  • Pour some epoxy down the center line of the sheet
  • Use the foam roller to spread the epoxy around until it is a thin even coating. 
  • Work an area and then use the 2" disposable brush to even out the epoxy.You do this by "tipping", just use the tip of the brush in light strokes moving in one direction,towards the direction of which you are applying the epoxy.
  • Spread the batch of epoxy and then mix another batch and keep going.
  • Keep a wet edge.
Next I'll let it dry overnight. This second Flow Coat eliminates sanding between the first and second coats.

Flo Coating the 3rd and 4th Coats

I chose to let the 2nd coat dry and harden overnight. This allowed me to sand the surface and get some of the imperfections taken care of before I got too far along. The outside of my Kingfisher will be painted but I want a real smooth finish so I want to take extra care with this process. The top edge of the side panels will be covered with a 1 3/8" gunwale. The bottom edge will be covered with about 4" of truck bed liner. So the middle sections of the panels are the critical areas. With that said I'm still going to try to get them as perfect as I can.

The next day I sanded the two exterior side panels with a random orbital sander. I used a 5" random orbital sander with 80 grit paper. I got my two fans running but on my respirator and got after it. I sanded down to the fiberglass in a number of areas but really tried not to go too far. The fiberglass is what gives the panel it's strength. It went pretty quick but I went through about 8 sanding disks. This is normal. If it isn't cutting change the paper. 

I talked to the guys at Raka Epoxy about the next step. The epoxy I'm using is their non-blushing type. So all I needed to do was vacuum the panels and then wipe them down with Acetone. You can also use Denatured Alcohol.  The Acetone cleans the panels and evaporates quickly.

I put on my Tyvek Clown Suit, rubber gloves, glasses, mask and got after it. Same process as listed above. I did one flow coat and waited about 4 hours and did the fourth coat. Looks pretty darn good. I'll wait until tomorrow and then take a photo. Then I can flip the two sides over and give the insides  two flow coats. They won't be fiber-glassed.

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Have any Questions or Comments? Let me know, Clay.