Fiberglass question

[Charles in SC]

I have a -7 slider. I am working on the fiberglass piece around the windshield.
I have it in pretty good shape but how do I know when to give up? I have been putting a layer of thick micro and then sanding to try to get it even (waveless). I do not know if I am getting it smoother or just creating a different set of waves with each layer.
At some point should I use body filler which I have found to be a little more workable and smooth sanding? The waves are probably no more than a few thousandths but I cannot seem to get rid of them all at once. There are so many different curves on this piece I have not found a good way to use a sanding block on it.

Another question.
Should I paint the fiberglass after I decide it is finished to protect it before the plane is flown and painted and if so, what with? Primer? What type?
Thanks in advance!

 

[RonB]

fiberglass

Hi Charles

When sanding my windshield fiberglass fairing we used the foam split water pipe insulation as the sanding block. It worked very well removing any waves and both initial and final sanding. No hard sanding block was used.

You will need a final skim coat to fill any pin holes. We used the AwlFair 2 part epoxy which requires overnight to set up and Bondo (yes I know it's a dirty word) which sets up in minutes. After almost 5 years we have no problems at all with the Bondo shrinking and cracking and I have neighbors who have been using Bondo on fiberglass for many years also with no problems.

As to the amount of layers we simply followed the method noted in the construction instructions section 9.

We used a shake care of gray primer for a temporary protection of the fiberglass until the painter had a slot a couple of months later. He simply sanded the gray primer off and used his 2 part product.

Hope this helps....

Ron