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Adhesive issues with Sika-Flex

Bill.Peyton

Well Known Member
When painting the fuse the painter decided to take the booth up to 140 degrees to accelerate the primer drying. Below is a photo of what happened to the left rear window. The top of the edge is picked away to reveal the sika adhesive on the surface. I also noticed the same thing with the doors and right side window at the rear only. all that was required to fix the doors and left side was a little block sanding. Only the right side was it actually lifted. Prior to the heat you could not detect any transition line at all.
The windows were attached using a 960-8 or -10 washers as a spacer and Sika adhesive. This was followed by 6 ounce 2" wide glass tape around the entire perimeter. The painter suspected that air was trapped in the adhesive, and the heat caused it to expand. I do not believe that the window flexed because the entire edge would have been lifted.
I repaired the left side by removing the tape and creating a v-groove for some epoxy mixed with flox and filling. One thing I noticed when I repaired this side was that the sika adhesive was right up to the glass tape, so the tape probably did not adhere the the Sika. I went back to my test panels to check the adhesion, and they were all good. I could not break the adhesive without breaking the plexi or the fiberglass.

IMG_2405.jpg
 
Window edges

I had the same problem. Where the windows were higher than the surrounding area, I tended to sand through the glass tape while trying to get a smooth transition. It wasn't obvious until I was about to send it to the painter. A close review showed where I was going to have problems in several areas around the windows, especially when the doors were flexed. Like you, I cut a grove, filled it and recoverd with glass tape.

Wings are on now and starting to "discuss" with the FAA why I should be allowed to conduct my Phase I out of Sacramento Executive (KSAC).
 
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