Coffin cover re-core

[clementsea]

Hey folks,

I posted questions about 36oz cloth last month... well.  I ended up buying that bolt of heavy cloth for $50 and I've decided to give it a try and re-core my coffin cover.  I'm using polyester White Water resin, plywood core and two layers of the 36oz cloth.

2 Questions:
1.  The thickness of the materials when placed dry in the prepped coffin cover comes to about 1/8 - 3/16" below the "lip" of the coffin cover.  I know it'll depend on how "wet" I leave the cloth & how well I weight the materials as they kick, but wondering if that 1/8 - 3/16" will be enough room once the materials are wetted out, or if I'll end up with too much material and it'll set up taller than the coffin cover "shell"...

2.  I also wonder what the "order" of the materials should be and the process itself. Here's what I'm thinking:
    - wet down inside of the coffin cover
    - place a layer of cloth inside coffin cover and wet out the cloth
    - place down-side wetted wood core (leave dry on top) on top of wetted cloth and weight down to harden on flat surface
    - at "leather hard", (no paraffin in resin) place a layer of cloth over wood core (after wetting out the top of the wood) wet that out
      and fill gaps with resin.
Is this the right order of materials?  Or should it be coffin inside/wood core/cloth/cloth...?  Is my process correct?  Any and all comments welcome. 
Thanks!

[RickK]

I think that you'd have better luck with something lighter, like 1208 or 1708 and some 3/4 or 1.5 oz mat.  That heavy woven is going to be tough to get around corners of any sharpness.  Usually they use that stuff for quick build up, not so much for building something for strength. I realize you bought it but I don't think this is the right application for it. My 

To Lam, on a flat fully supportive surface I would wet the cover, lay 3/4 or 1.5oz csm against the cover and hard roll, then a layer of 1708 cloth side down wet out and hard rolled and then wet the bottom side of the wood and stick the wood (are you going to bevel the edge (top side) all around?) and lay some sheet plastic over it and weight it down to kick.  Plastic is to keep the inevitable resin from getting everywhere.
Then wet the top and lay the 1708 mat down (or you could lay some 3/4 or 1.5oz and then the 1708 cloth down) and then another layer of same a little bit wider all around.  Lay a piece of plastic on top, a larger piece of wood and then some heavy stuff on top of that to keep flat until it kicks.
That's how I did my covers and it worked great. 
Someone else may have a different approach and will be by soon with theirs.

[GoneFission]

What Rick said...     Get some weight on it to ensure bonding - maybe even drill some holes on a grid to allow the excess resin to bleed through...

[clementsea]

OK... please bear with me here, cause I'm not familiar with the glass/matt terms...
3/4-1.5oz csm is matting?
1208 & 1708 I'm assuming is matt on one side and woven glass on the other?

Still learning the lingo..

[RickK]

You got it.  CSM or Matt is used with Poly resin because poly melts some binders in it and they all become one.  It's not great with epoxy.   Matt comes in all kinds of weights. Like 1.5oz is really 2x3/4oz pieces rolled together.
Cloth is woven material. 1708 is a normal staple used. It has cloth woven at 45 degree bias. There are versions of 1708 that doesn't have matt on one side too (1708-DB, depending on who you buy from).  There are different weight cloth too (as you know) and they are woven differently - like 1808 is 18 oz woven (with csm) on a 90 degree bias.  I just tabbed in the liner of my 170 with 12 oz cloth that has no matt.  Not sure if they make 1208 that has matt, they probably do. 

There is a primer on the terms and what the stuff looks like somewhere in the Generic Fiberglass forum I think.
Here is a link to ClassicMako - scroll down about halfway  http://www.classicmako.com/forum/topic.asp?TOPIC_ID=16723

[Capt. Bob]

There is a primer on the terms and what the stuff looks like somewhere in the Generic Fiberglass forum I think.

Resource forum:
http://classicaquasport.com/smf/index.php?topic=2902.0

[clementsea]

Thanks for the references guys!  I'll do some reading up on the subject... my only experience with glass is from building windsurfing boards with Clark foam blanks and E-glass, so, I'm stepping outside my envelope here...