12-25-2007
Paint nor bondo stick easily to POR-15 but their super-bondo does. After painting the highly distressed area and letting it dry I applied a layer of their body filler over the whole area and sanded away all the high spots leaving the filler and encapsulated rust covered by paint and their bondo. They say that it's 5 times as hard as standard body filler. It's reinforced with glass fibers.
I fitted the window trim to act as a guide to the application of a coat of body filler. You can see the gap I need to fill to match the original opening.

The patched area got a base coat of bondo, Thin layers of build-up are better than gobbing on filler.

After getting the patched areas to line up with the window trim I shot a layer of primer over the bondo to protect the freshly sanded metal. This layer of paint, when block sanded, will reveal further neecessary work.

After block sanding the sides I applied a thin layer of bondo over the rest of the lower panel.
I was careful to keep the layer thin so that the curvature would be maintained. After it hardened I started hand sanding but all of my sponges or sanding blocks only made contact at their outer edges.

I resolved that problem by making my own sanding drum. I used 3M adhesive on the tube and back of the paper. It took a couple of attempts to get proper positioning but it produced a very effective sanding tool. I sanded lengthwise while moving the sanding tube in a cross-hatch pattern

A coat of primer to protect what I'd completed.

After it dried it looked flat and straight. I went on to the next task. The rust at the top of the window fooled me. I thought it was just surface rust but it was some serious damage. Apparently there had been a sealant installed but none of it got behind the trim clips. Each clip became a water trap and this is the result.

I used a die grinder with wire brush and holes started to appear. A burr revealed the extent of the damage.

[img]http://memimage.cardomain.net/member_images/8/web/752000-752999/752157_126_full.jpg[/img]
The super-bondo instructions said that it required a backer but there was no way to install one in this location. A different approach was required. I decided to fill the cavity behind the damage with expanding foam. It will cut off all oxygen to the back side of the metal and it will act as a backer for the filler. I'll be making a small recess behind the metal edge so the filler will encapsulate the rust.
[img]http://memimage.cardomain.net/member_images/8/web/752000-752999/752157_127_full.jpg[/img]
[img]http://memimage.cardomain.net/member_images/8/web/752000-752999/752157_128_full.jpg[/img]
Next up is to clean the inside lip of the trunk lid and give it a coat of paint. I'll then reinstall it and fill the antenna holes. Then the sail panel repairs. I've got an idea what I want to do there.