Sanded to the Weave

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Sanded to the Weave

Post by BillB » Thu May 25, 2006 1:48 pm

To make a long story short - in prep for varnising I have sanded down to (not though) the fiberglass weave in some areas on the interior of my Nomad. I have built this boat bombproof and have two layers of fiberglass on the football areas - both inside and out. I had intended on applying another coat of epoxy to cover these spots. But to avoid more sanding I am wondering - what if I go straight to varnishing? How bad will the spots look that are sanded to the weave? I wiped them with a wet cloth to see if they disappered. Mostly they did - there was just a slight cloudy appearance but otherwise not bad. If I must re-coat with epoxy can I roll it on then wipe most of it off? I was hoping this might give me a thin, low weight coating that would still cover those sanded through spots. Thanks - Bill.

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Patricks Dad
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Post by Patricks Dad » Thu May 25, 2006 2:15 pm

Bombproof - 2 layers of fiberglass on the football (in and out) and you're worring about the weight difference between a rolled on layer of epoxy in a small area and wiped on?

I'd roll it on, let it set completely and then scuff it with a pad before varnishing.

Do some weight lifting while the epoxy is curing so you can handle the extra weight :eyebrows
Randy Pfeifer
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Sanding the weave

Post by ealger » Thu May 25, 2006 3:50 pm

Bill, if you varnish over exposed glass weave, it may look good in your shop, but will be visible in the sunlight. Roll on some epoxy over the spots, as Randy suggests, and feather the edges. Make sure you let the patch cure completely before varnishing or the varnish will not dry.
Ed Alger

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Post by AlanWS » Thu May 25, 2006 5:33 pm

Do what they say! If you don't, you will make the places you sanded to the glass a lot more noticeable.

And I if you do varnish over the exposed glass, you might feel compelled to read this explanation of why it looks bad: Light reflection at an interface between two transparent substances depends on the differences of their indices of refraction. Since glass and epoxy have similar indices, there is not much reflection there. Varnish has a significantly different index, so there will be significant reflection at the junction between air and varnish, and between varnish and epoxy, and a different reflection between varnish and glass, if present, that would be quite noticeable in the sunlight.

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Post by BillB » Fri May 26, 2006 6:01 am

Many thanks Guys. I will recoat.
Mine is a cautionary tale about the wisdom of overbuilding. I put double layers of fiberglass (on the football) to strengthen the bottom and avoid potential oilcanning - which I read on this forum could be a problem with this canoe. But the cloth floated a bit on the inside and I could not squeege it flat. So the bottom inside is rippled - which lead to difficulties in sanding and thus hitting the weave. On the next canoe I won't add the second layer on the inside. The outside presented no problems in applying the second layer. Thanks again - Bill.

P.Dad - Good thing I've been hitting the gym lately :wink

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