Do I have to "rough" up every shiny spot on the canoe in between the epoxy and the varnish? (outside hull currently - inside the same?)
Some places you can still see the glass pattern and I'm afraid if I go much lower I'll cut the cloth. I have a "zillion" (it seems) of those tiny spots.. seems like someone else asked this question lately but I was unable to find it.
Thanks in Advance.
Shawn Waite
shawn@shawnwaite.com
Sanding in between Epoxy and Varnish - shiny spots.
OK, I'll have a go at it, although I've only one boat under my belt, and the varnish hasn't been on very long.
When you apply filler coats, the weave pattern of the glass can telegraph upward with each coat, so even though it might look like you're about to cut into the glass during sanding, it ain't necessarily so. I did a thorough powersanding of my outside hull and deck (with ROS), after a couple of fill coats, to eliminate the dimpling effect of the weave pattern. I sanded until it was smooth, and touched the glass only in one or two spots. There were a few shiny spots remaining, but I guess about 99% of the surface had been scuffed by the sander. I then put another fill coat on top of that. When that was cured, a quick wet-sanding by hand was all that was needed to scuff the entire surface.
Your mileage may vary, depending on how much epoxy you actually applied. This was my first-ever fiberglassing project, and I probably used more epoxy than strictly necessary, but it all worked out in the end.
When you apply filler coats, the weave pattern of the glass can telegraph upward with each coat, so even though it might look like you're about to cut into the glass during sanding, it ain't necessarily so. I did a thorough powersanding of my outside hull and deck (with ROS), after a couple of fill coats, to eliminate the dimpling effect of the weave pattern. I sanded until it was smooth, and touched the glass only in one or two spots. There were a few shiny spots remaining, but I guess about 99% of the surface had been scuffed by the sander. I then put another fill coat on top of that. When that was cured, a quick wet-sanding by hand was all that was needed to scuff the entire surface.
Your mileage may vary, depending on how much epoxy you actually applied. This was my first-ever fiberglassing project, and I probably used more epoxy than strictly necessary, but it all worked out in the end.
Hi, Shawn,
How small are the glossy spots? And how much of the total area would you estimate they cover? If the gloss is from the weave of the cloth, you might try sanding down a little further, if you've applied enough epoxy over the glass. You should be able to get some idea of what sanding down to the glass looks like by sanding at the sheerline, in the area which will eventually be covered by the outwale.
If you've been reading CanoeCraft, sanding down the interior requires only a light sanding to knock the high points off and keep a rough texture. The varnish is applied onto this, so there is some gloss due to weave texture. On my canoe, the varnish is holding up OK in the interior, there may have been about 50% gloss remaining. So I would guess that if you have some small pecentage of the area in gloss on the exterior, the varnish should still remain attached.
Ideally, the exterior should be sanded smooth and be totally scuffed - I'd go with what Ken described first.
How small are the glossy spots? And how much of the total area would you estimate they cover? If the gloss is from the weave of the cloth, you might try sanding down a little further, if you've applied enough epoxy over the glass. You should be able to get some idea of what sanding down to the glass looks like by sanding at the sheerline, in the area which will eventually be covered by the outwale.
If you've been reading CanoeCraft, sanding down the interior requires only a light sanding to knock the high points off and keep a rough texture. The varnish is applied onto this, so there is some gloss due to weave texture. On my canoe, the varnish is holding up OK in the interior, there may have been about 50% gloss remaining. So I would guess that if you have some small pecentage of the area in gloss on the exterior, the varnish should still remain attached.
Ideally, the exterior should be sanded smooth and be totally scuffed - I'd go with what Ken described first.