Overhead grp repairs

Wet out your tape/glass on a polythene bag which

is lying on a small sheet of foam(old cushion or mattress?) which is lying on a sheet of ply. Raise the whole set up into position and jam the ply upwards with props. Peel off the ply, foam and polythene after 30 minutes .
 
Polyester v Epoxy

The test of any bond is to make up a test piece ...... laminate each side to a piece of junk wood for leverage ...... once cured, try and break the two apart. If the new laminate breaks cleanly away from the old: the bond was not good enough.

If you have plenty of surface area polyester may be good enough : a gradient of 12:1 is the minimum generally accepted. Well prepared epoxy will usually be much stonger.

Never apply epoxy to uncured polyester ..... the styrenes given off by the polyester will prevent the epoxy from curing to full strength.

Never apply polyester to epoxy .... the mechanical bond will be very weak.

Polyester has a much weaker mechanical bond than epoxy. There is no way to get a reliable chemical bond on a cured laminate as far as I am aware.

Well put ;)
 
Polyester v Epoxy

The test of any bond is to make up a test piece ...... laminate each side to a piece of junk wood for leverage ...... once cured, try and break the two apart. If the new laminate breaks cleanly away from the old: the bond was not good enough.

If you have plenty of surface area polyester may be good enough : a gradient of 12:1 is the minimum generally accepted. Well prepared epoxy will usually be much stonger.

Never apply epoxy to uncured polyester ..... the styrenes given off by the polyester will prevent the epoxy from curing to full strength.

Never apply polyester to epoxy .... the mechanical bond will be very weak.

Polyester has a much weaker mechanical bond than epoxy. There is no way to get a reliable chemical bond on a cured laminate as far as I am aware.
 
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