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The following letter & pictures were submitted by Roger during November 2003.
From: Roger Isackson
[About fiberglass and resin fabrication,] I attempt to make all of my thicker lay-ups a semi-continuous process. I lay out most of my reinforcements on vacuum bagging film on which I draw the outline of the reinforcement. I put the marker side down so as not to get ink in with the sticky stuff and I use masking tape to keep everything from sliding around on the bench. I lay the glass on the resin painted surface of the film then stipple with a chip brush of appropriate size. I have found trimming the first 1/8 " off the end of the brush with a very sharp scissor makes the process go a lot better. I use no rollers as I hate the way they pick up glass strands along the edge of the cloth. This is especially bad when the orientation is 0-90. I limit the thickness to 4 or 5 plies, any more than that and I find myself losing the shape of the lay-up while chasing bubbles and working resin either in or out of the pack, whatever is necessary. So I put it in place and mix up another batch. Usually by the time I am ready for the next 4 or 5 plies, the previous ones have set up enough so I don't have to worry about moving them around. I know if I can dent the resin with my fingernail I am going to get a good bond.
Actually according to Dows' literature a chemical bond is capable a long time after you are unable to dent the resin. Up to 24 hours I believe. I don't like to let it go that long though.
I use acetone for cleaning brushes mostly. I like to give the surface an initial wipe with a clean cloth and good acetone. But that is where it ends. I then sand with 150 grit and vacuum... twice! I am very careful about contaminates around the shop however. I also like to prefabricate parts on the bench where I have more control of the quality. Whenever I know it is going on a fully cured area that is.
Remember the fix for the fragile balance horns Mike Bowes' shop recommended? I made the fix and am going to send you a sequence of photos. [Included below.]