Last week I had a discussion with another builder in New Jersey about his
discovery that some of his layups could be peeled off fairly easy. We
discussed possible problems and I went on building my first wing. Well, it
kept nagging at me so I decided to check some of my recent wing layups. Both
aileron hinge reinforcements came up suprisingly easy, as did the front and
rear spar portion of the wing root layups! The spar area is the same area my
friend had problems with.
I called John Hurst and Bob Setzer(sp) in Lakeland to get their input. Bob
seems to be the epoxy guru and his response was consistency. His method.....
1) Check the temperature of the surface of the lay-up area. Get above 70'F.
2) Wipe down the area of the lay-up with acetone or Methylene Chloride to
remove any grease, oils, or mold release. Then don't touch that area without
gloves!
3) Use 36 or 40 grit sandpaper to really scratch up the surface for bonding.
4) "IMPORTANT PART!" Lightly brush the area with your resin mix.
5) Then apply the lay-up. Either by laying down the glass on the area and
wetting in place or wet out the lay-up on plastic sheet and apply all at
once.
6) Keep the temp up for at least four hours.
It will then take at least seven days to achieve full strength. It may be
hard on the outside but it's still rubber on the inside. Then you should not
be able to peel off the layers without removing some of the base material. If
you peel it off and the back of the layers is babybutt smooth, then the
surface was not prepared right.
Anyone else have any good tips or techniques that might help?
Mike Duane A207
Redding, California
XS Trigear
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