Re: [Paddlewise] stitch & glue

From: Gordon Snapp <grsnapp_at_charter.net>
Date: Fri, 8 Aug 2003 21:07:11 -0500
Greetings.  I'm no expert, but I've built a Chesapeake 17, and I'm presently
constructing a Guillemot.  I've hung around the bulletin boards a lot, so my
ideas may have some validity.  (Then again, they may not.) (Guillemont BBS:
http://www.kayakforum.com/cgi-bin/Building/index.cgi) (Chesapeake BBS:
http://www.clcboats.com/forum/bbs.pl/cart_id=b1d67bd1a598e7163ef0335bd82e7c7
1/)

>What determines
> the weight of fiberglass cloth? Say 4 oz verses 6 oz.

I don't know, but I'll bet that if you posed that question on one of the two
forums listed above, you'd get plenty of knowledgable responses.

Is there a good
> substitute for wood flour?

I suppose it depends on what you want it for.  I've used wood flour mixed
with epoxy to make fillets, for end pours, and to make a rock-hard putty for
filling gaps between strips on the Guillemot I'm building.  You can use
micro balloons to make a putty.  My understanding is that the resulting
putty is much lighter.  I don't know how it compares strength- and
hardness-wise.  I've also used Cab-o-sil, or silica powder as a thickener
for epoxy, when I wanted to use the epoxy as a bonding agent (glue.)

Why doesn't epoxy bond to older epoxy  (say > 3
> days old) unless it has been lightly sanded first?

My understanding is that the new epoxy will chemically bond to the old epoxy
if you apply it before the old epoxy has completely cured.  If it has cured,
then it's too late to form a chemical bond, and you need to create more of a
physical bond between the two layers by roughing up the old epoxy.
Incidentally, the strip-builders recommend not sanding the wood with finer
sandpaper than about 120 grit, to make sure that the resulting roughness is
coarse enough for the epoxy to adhere to.  I would think the same would
apply to a layer of epoxy - I wouldn't fine sand with 600 grit sandpaper if
I was just roughing it up for a better bond.

Why does slow cure epoxy
> create a stronger bond than 5 minute epoxy?

Does it?  I'm wondering if 5 minute epoxy is actually epoxy, or really
polyester resin?  Could it be that the resin to hardener ratio is hard to
control?  Could it be that there isn't time to get it thoroughly mixed when
you only have 5 minutes of working time?????

>
>   I am considering either the Pygmy Coho or Arctic Tern as my next kit.
It
> will be a day boat & weekend camping boat.  Opinions as to how appropriate
> these boats are for these  activities?
>
No opinion, as I have no experience with these.  What kind of boat are you
building now?



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Received on Fri Aug 08 2003 - 21:05:00 PDT

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