Plastifix
I've had a crack in my canopy for four years, that I've had to stop drill twice. After reading Scott's article, I dropped him an email and he provided with some great advice. I'd accumulated several discussions strings on canopy repair over the years, none of which looked viable to me. After talking to Scott, who is in product development at the company who sells PlastiFix, I bought his product.
Scott sent me some pix of the B-25 turret canopy repair, to show me that they were not really clear, but the best you can do in a bad situation. I used their clear product in making a repair on my RV-4, but tiny bubbles form in the chemical and still prevent it from being clear. However, it seems to have made a strong repair, which I hope will stop any further problems.
I used a Dremel tool to cut a V-groove along the crack, which is the recommended method. I wasn't certain from their directions but cut it all the way through, with just a small opening along the crack on the outside. This allowed the chemical to fill in the opening down to the tape I placed on the outside along the crack, to prevent dripping. Fortunately, the crack was on the right side of my tip over canopy, allowing gravity to work for me, as I filled from the inside. A repair on a vertical surface would be more difficult.
PlastiFix comes in two bottles. One is a powder and the other a clear liquid. I poured a thin layer of powder in the groove, followed by a layer of the clear catalyst. I used a needle applicator to control the application. PlastiFix sets up in less than a minute as I used it and I applied about 5 coats to fill slightly above the surface. Several sandingings, using progressively finer grit, smoothed the finish. A final rubbing with auto rubbing compound polished it out and it was done.
The repair is opaque, but if it stops the problem, I'm happy with the repair and see it as a battle scar on my faithful "flyer."
The PlastiFix kit cost around $30 and I've got plenty for other plastic repairs.