Ok, i’m relatively new to sanding, actually, i’m relatively new to it all really. Anyway i’ve glassed probably 3 boards, all RR epoxy, it’s all i know. My question is general though, has nothing to do with the resin i’m using, just thought i’d make it known. Ok, basically…do i sand my bottom lap flush with the rest of the bottom after the lam or during the hotcoat sanding stage? I’m thinking i should flush the lap before the hot coat so that i have a nice smooth hotcoat and easy sanding thereafter. Yet i have been doing it the opposite. Also, when i try to get the lap flat during the hotcoat sanding stage, i expose the laps weave, which has cause me to do another thinner hotcoat again a couple times…which in turn adds sanding, weight, time, money and headache to the equation. But i have not tried sanding the lap flush with the bottom after the lamination, cuz then i’m really into the weave, there there is two layers here, so maybe it’s not such a big deal.
Any and all help is appreciated…i’ll be in the archives.
I know surform is great to rough shape foam and to use on wood, but hardened resin?? Really? Any video clips of using a surform to level out laps?..or maybe a slight elaboration. I’ll do a search, thanks.
You can also use 60 grit on a block for the lap on the top or pneumatic grinder with a 2" wheel. Then use a grinding wheel on your variable speed sander for the bottom lap. Just go slow. I used to use a surform for laps. Got fed up with that biz.
If you knock off the worst of the high spots with a grinder, surform or file and “baste” the laps before fill coating, you’ll have a somewhat heavier board (?) but sanding will be easier and you’ll protect some of the glass from the grinder.
By basting, I mean simply brush some resin over the laps. This will fill/blend in the edge where the lap ends. I usually lay a tape apron along the edge before basting and remove after the final fill coat starts to gel. The fill coat can be applied as soon as the baste coat starts to get solid. Remove tape as soon as practical.
Sand as usual and note that less of your laps need to be ground away to get a flush surface.
being “relatively new to everything”, i wouldn’t be too quick to take a pneumatic grinding disc anywhere near your board. one slip and it’ll take off a lot of foam…or a finger.
I use a surform for semi- hard resin glass humps and details and a flat bastard file for hard stuff. As far as knockin down the entire bottom lap…why? you lose strength and the gained flex results in massive tuck and rail zippers and broken boards. Why even lap at all if you plan to remove it by flush grinding.?.
i do a thin cheater coat (pulled off hard) after deck lam. then hotcoat bottom. then hotcoat deck.
haven’t had any problems with bubbles since i started adding a splash of DNA to the hotcoat. in the winter months (when the temp drops down into the 70s), i give the resin a hot water bath before mixing things up. works like a charm.
A curved surform seems like a good call, thanks for the info. I’ll post some pix of what i’ve been working on later tonight. Looks like cali’s getting a thanksgiving swell, yewwwww.
