Finishing Kit

June 24, 2012

The Canopy Fairing - 8.0 hrs.

I'm back to work on the canopy! It's time to get to work and get this thing finished. I've been studying the best way to do fiberblass layups and getting everything ready. My friend Bill DeLacey, who helped me with the Sika job, generously offered me a copy of his notes from a very popular workshop that he attended on this very subject. I've never been to any workshops, so this was very nice to have. So after studying those notes, along with what Vans has in the manual, I feel like I'm ready to go.

The first step was to lay down a strip of this heavy PVC tape, purchased in the aviation aisle (i.e., plumbing section) at Home Depot. It's called Pipe Wrap tape, and it's 20 mils thick. Standard electrical tape is 7 mils, so this is substantial and should stand up to a lot of sanding. It's nice and wide, too, so it's much better than electrical tape in that regard as well. I very carefully placed it about an inch above the plexi/skin joint, precisely where I want the fiberglass fairing to end. I may end up extending the fairing up a bit higher, but I wanted to start in a conservative place. I can always go higher up, but you can't go lower!

Next, since I'll be applying an epoxy resin mixture that is black from pigment mixed into it, I realized that black resin and black tape will be hard to distinguish when sanding. So I applied another strip of orange electrical tape right on top of the PVC tape. I also applied another layer of tape on the forward side, although I realized later that this is really not necessary.

Here's a closeup after really scuffing it all up. The notes from Bill said to use 35 grit sandpaper. Wow. That's rough stuff. I had some 40 grit on hand, so I went with it. It's really rough stuff, too. Here's what it all looks like after #40 sanding. It really gets into the plexi and also the aluminum on the skin.

Now it was time to cut some fiberglass strips. I used my little "pizza cutter" cutting wheel and a long straightedge to make the cuts. Piece of cake.

Here are my strips, all laid out. They go from 3/4" wide up to about 2-1/4" wide. I plan on about 7 layers of glass to fill in the fairing.

Now it's time to take a deep breath and dive in. I mixed up some resin (I'm using West Systems, of course) and added some black pigment. I thickened it with West Systems number 403 microfibers and brushed a thick layer all across the plexi. The idea is to leave a black layer because you will see the fiberglass from inside the cabin if you don't color the mix with black pigment. Then I mixed up another batch of resin and started laying strips. I started with the 3/4" wide first, and went to a wider layer on top of that. Here, I'm applying the 3rd layer. I brush on the resin, lay the glass down, and sort of pat it into place with the end of the brush, then add more resin over the top to make sure it's saturated and there are no bubbles in the glass. Then, it's on to the next layer. This really isn't that hard.

Here's a closeup after 3 layers. You can see the thickened layer of resin/ 403 microfiber mix above the edge of the fiberglass, covering the plexi up to the orange tape. Each successive layer of glass is wider and gets about 1/8" closer to the orange tape. The last layer to go down will be right up against the orange tape. The idea is to have it one layer thick right at the stopping point.

For these last 4 layers of glass, I used resin mixed without any pigment. I figured I didn't need it anymore. BIG MISTAKE!

Here it is when I was all finished. Looks pretty good, doesn't it? I figured since I had a nice layer of black mix under the glass layers, I didn't need any more pigment. I was so excited at this point, I didn't even think I needed any peel ply. I'll just let this harden and sand a little and go from there. Or so I thought.

So I was taking pictures and admiring it all, ready to call it a night and go to bed. Then, almost as an afterthought when I was all done, I lifted up the canopy and climbed inside, just to get a feel for how this looked. Boy, was I shocked at what I saw. Those last 4 layers of glass diluted the black mixture that I thought was covering the plexi, and the light was shining through it. You could see the somewhat-blackened white fiberglass right through the windscreen. It looked horrible! There was a nice black layer coming up about 5/8", right to where I stopped using the pigment, but that last 3/8" was white. I was shocked, but also very glad that I just happened to climb inside to take a look. I still had time to fix this, if I acted fast.

So I hurried out of the cabin, grabbed a pick, and started lifting up layers of glass and resin. It broke my heart to have to do this, wasting the fiberglass and all those pumps of expensive epoxy. All my nice work was being torn off. But I knew I had to lift off those last 4 layers, clean the resin off down to the plexi, and do it all over again. Either that, or I'd be staring at this mistake (along with every passenger I ever fly with) for the next 20 years. So I went to work. Boy, was this ever a race! The epoxy from the earlier layers was already hardening up, it was stiff and hard to remove. By the time I got 4 layers of glass pulled off, I was seriously wondering if I'd get the remaining resin removed from the plexi. I worked on this, literally for several more hours. With each passing minute, the remaining epoxy got even harder, and I had to get it off. I had already had a full work session, this just extended it late into the night. I knew I'd be paying for it the next day, but what could I do? I just kept working to get it off, using scraping tools and whatever I could try. I had originally hoped to get the new layers back down, so it could all harden at once, but it was now very late. I was exhausted. I still had new strips of fiberglass to cut. I called it a night.

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