Hi Mark,

First, thanks for the great comments.

Some of us are working on the KayakWiki site, as a FAQ, of sorts, for this BBS. Would you mind if I added your posts to a Vacuum Bagging section?

Thanks,
Shawn

: First off, I used the term "fill coats" to describe the adding of
: resin AFTER the
: glass to smooth the surface. Not the resin coat on the raw wood to promote
: adhesion.

: My comment about not using a fill coat meant: that on the interior the
: surface doesn't need to be glass smooth. And the bagging process will
: eliminate pinholes. So you probably don't need any smoothing coats after
: the initial glassing of the interior. If any, just a very thin sealing
: coat.

: I envisioned the process going like this...

: Strip the entire kayak. Split the halves.
: Glass the exterior of one half (bottom/top doesn't matter to me).
: Add resin & sand exterior until surface is smooth. Or maybe stop after
: one coat, to get the interior done before it warps.
: Vac bag layup the interior of the half that is done on the outside.
: Do the other half similarly.

: My responses on the bagging... again with the disclaimer that I've never
: built a kayak or bagged over cedar...

: unlike a regular layup, I deliberately apply excessive resin when bagging.
: Not tons of excess, but you NEVER want too little. The bagging process
: squeezes all the excess up through the peel ply into the absorbent layer.
: It also leaves practically zero bubbles (they get 'sucked' out). The
: removal of excess resin, and the removal of resin between the substrate
: and the cloth or between layers of cloth, and better bonding to the
: substrate is what I see as the major advantage of bagging. I haven't had
: good results with bagging forcing epoxy into small irregular interior
: shapes.

: You've GOT to do a test panel to believe it. The cloth and resin get so
: squashed onto the substrate, it's REALLY cool. And the finished surface
: looks like the original cloth surface (only clear), because it gets so
: fully impregnated with resin and has 0 excess. The vacuum will also draw
: the resin into the substrate pores, so I doubt there would be any adhesion
: problem, unless it ran dry of resin (again that never use too little
: issue).

: My vacuum setup does have a tank, which acts as a drip catch, but I've never
: seen any go in the hose, never mind all the way to the tank. Fact is, the
: tank doesn't help if you have a persistent leak. All it does is make the
: motor cycle slower. Same percent run time, just longer intervals. I've
: also never used genuine mastic, I've always contact cemented my 'bags'
: shut. I use dropcloth poly for bags, fold it over the work, spray around
: the edges and stick it shut. Nylon "parachute cloth" works for
: peel ply. And terry cloth towels work for the absorbent layer!