The glass canard guys know this one, but the new guys probably don't. Yesterday's shop work brought it to mind, so I'll share.
Eventually your glass work gets down to final contour and filling surface weave. In past posts I've suggested laying on more dry micro ("dry" meaning like stiff peanut butter) than seems strictly necessary, as you want to contour and sand just once. The lowest low spot in your fill application should be higher than the final contour....which brings up the subject of rapidly removing all the excess. Sanding down the excess can be tedious and dusty.
During cure, epoxy goes through several stages, from viscous liquid, to sticky jell, to firm but flexible, and on to hard cure. You can save a lot of work with some timing.
About 4 hours into cure (assuming West and slow hardener) grab a Stanley Surform file. The micro is still way too soft to sand, but a Surform will rip the excess down to contour very quickly. You get nice neat shavings (like dry cheese), not dust; you don't even need a mask. Just swipe the Surform across the surface. If the shavings don't stick to the file, it's ready. Stop just shy of final contour and come back in 24 hours for a lot less final sanding.
If you wish you can slick off the Surform marks with a vixen file at the same time. Push it off-angle about 30 degrees.
Same idea works with polyester body fillers (Rage, etc), but the time window is not as wide.
Surforms come in several shapes and sizes. I've been using this little one for years.
Eventually your glass work gets down to final contour and filling surface weave. In past posts I've suggested laying on more dry micro ("dry" meaning like stiff peanut butter) than seems strictly necessary, as you want to contour and sand just once. The lowest low spot in your fill application should be higher than the final contour....which brings up the subject of rapidly removing all the excess. Sanding down the excess can be tedious and dusty.
During cure, epoxy goes through several stages, from viscous liquid, to sticky jell, to firm but flexible, and on to hard cure. You can save a lot of work with some timing.
About 4 hours into cure (assuming West and slow hardener) grab a Stanley Surform file. The micro is still way too soft to sand, but a Surform will rip the excess down to contour very quickly. You get nice neat shavings (like dry cheese), not dust; you don't even need a mask. Just swipe the Surform across the surface. If the shavings don't stick to the file, it's ready. Stop just shy of final contour and come back in 24 hours for a lot less final sanding.
If you wish you can slick off the Surform marks with a vixen file at the same time. Push it off-angle about 30 degrees.
Same idea works with polyester body fillers (Rage, etc), but the time window is not as wide.
Surforms come in several shapes and sizes. I've been using this little one for years.
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