: Being a newbie here, I am somewhat reluctant to step in. However,
: my experience and information suggests that pre-coating the wood
: is unnecessary and could be counterproductive. I just finished
: glassing my hull, and had no problems whatever putting the glass
: on bare wood. The experts at Mas epoxy state that pre-coating is
: not necessary with the cloth weights we use for kayaks. I
: suppose that this advice might be less applicable to heavier
: (for kayaks) S-glass which is somewhat harder to soak, but
: others will have to wade in on this as I have no experience. I
: was using the 3.25 oz E-glass from Thayercraft, and had no
: trouble wetting it out with Mas epoxy mixed about 75% slow and
: 25% fast hardener.

: Putting the glass on directly avoids a step in the process. Also,
: if you have been careful with your sanding, the smooth clean
: surface will not have any hidden snags to grab the weave of your
: cloth.

: There are numerous sources of information on the topic, but this is
: what worked for me.

: 1. Sand and clean the hull. I wiped it down with a rag dampened
: with isopropyl alcohol (as per the experts at Mas) the night
: before glassing to remove the last bit of dust. Do not use paint
: thinner or acetone.

: 1b. (optional) Place masking tape along the line at which you wish
: to trim the glass if you are going to trim it short of the edge
: of the wood. I left the edge of my hull bare so I could leave
: one line of staples in place until the deck strips were glued in
: place. (see my earlier post on tidy fiberglass edges if you are
: interested.)

: 2. Preheat the shop to a warm temperature, I did my work at about
: 77 degrees F. Do this well ahead of time so that everything is
: up to temperature. I warmed the shop overnight before doing the
: glassing the following day. I have read that some builders let
: the temperature of the shop decline slightly during epoxy curing
: so as to avoid bubbles being generated by air pockets in the
: wood, but I did not bother with this and had no bubbles. Warmer
: temperatures reduce the viscosity of the epoxy, and make wet out
: of the laminate more effective.

: 3. Roll, don't drag the glass onto the bare hull. Use clean rubber
: or plastic gloves to keep finger oil off your glass.

: 4. Use a clean soft paint brush, not your hands, to gently smooth
: the glass into place. It should lie perfectly smoothly over the
: entire surface, with the possible exception of the stems,
: depending on their curvature and the looseness of the glass you
: are using. Getting the glass on tight and smooth at this point
: will help avoid wrinkling when you squeegie later. Don't worry
: about it if the glass will not lie perfectly on the stems. You
: can trim the glass just short of the portion of the stems which
: will not behave themselves. Don't bother trying to fold the
: glass over the stems either. Later, you will want to apply some
: bias cut cloth over the stems to reinforce them anyway, and the
: bias cut cloth will hug the surface of the stems perfectly. The
: stem in the photo has the hull glass trimmed slightly short of
: the stem, and up to five layers of 3.25 oz cloth over it.

: 5. Measure and mix your epoxy carefully, about six ounces or so per
: batch if using a slow hardener. Mas recommends mixing for at
: least two minutes (time it to see how long this really is). With
: the Mas epoxy I was using, I did not worry at all about bubbles
: during mixing. They do not persist through the glassing process.
: Other epoxies might be different, but I would expect that any
: low viscosity epoxy would work similarly.

: 6. Apply the epoxy by pouring on a small puddle and spreading it
: around with a roller or brush. If you use a roller, make sure
: that it is compatible with epoxy before you try it on your boat.
: Otherwise, you could end up with a boat decorated with bits of
: disintegrating roller cover. What you apply the epoxy with is
: not all that important to the end result. The main point on your
: first attempt is to make sure that you apply enough epoxy to
: soak both the glass and the wood. Soaking takes a few minutes,
: so don't worry if the epoxy does not wet through right away.
: Just keep going, and monitor what you have done to see how it
: behaves. Apply more epoxy as necessary to any spots that seem to
: need it. You will probably waste a bit until you get used to how
: much is required, but this is better than not using enough.
: Don't worry about bubbles at thus stage, they will disappear
: later. IMPORTANT: If the epoxy you are using starts to heat up
: in your mixing cup while you are glassing, toss it and make a
: smaller batch next time. Once the epoxy in the cup goes
: exothermic, it may not stay liquid enough for long enough to
: properly wet the glass out.

: 7. Now for the bit that counts. After you have applied epoxy over
: some distance of hull (I actually did one whole side at a time,
: but my epoxy is quite slow, and the boat is small), you need to
: squeegie off the excess. Not all squeegies are equally
: effective. The best in my experience are the relatively heavy
: rubber ones that you can get from a specialist composites shop.
: The thin plastic ones don't work as well for me.

: Whatever squeegie you use, how well you use it will affect the
: quality of your finish and the weight of your boat - this is
: more important than the method of putting the epoxy onto the
: hull in the first place. The idea is to remove all the epoxy
: that can be readily removed, while leaving the glass tightly
: adhered to the hull and still filled with epoxy. If you get it
: right, the resulting laminate will be light and strong, and
: there will be few runs or drools to clean up later. With
: properly squeegied glass, you will see the texture of the glass
: clearly over the entire surface, and the surface will be as fair
: as the hull underneath. This is more easily seen and experienced
: than described, but getting all the excess epoxy out takes a bit
: more pressure and perseverance than I initially expected. Start
: off with lighter pressure, and work up to fairly firm pressure
: which fails to remove any more epoxy. Cut a notch in the side of
: a plastic cup - make the shape similar to the edge of your
: squeegie. After a squeegie stroke, run your squeegie through the
: notch to scrape the excess epoxy into the cup. To learn about
: all this before tackling your boat, it would be a good idea to
: apply a couple square feet to a scrap of plywood to see how all
: this works.

: 8. As you progress, monitor the areas you have squeegied, and if
: any spots develop that seem starved of epoxy, apply some more,
: and re-squeegie. With the Mas epoxy I used, and the time I left
: it before squeegying (is that really a word?), no starved spots
: developed.

: 9. Continue to monitor the hull for a few hours after glassing to
: watch for any trouble before the epoxy to gels. The areas to
: watch are the stems, but don't worry too much about them. Any
: glass that lifts near the stem can be trimmed flush to the hull
: and will be covered by the stem reinforcement later.

: 10. After the epoxy gels, what you see is what you get. Admire the
: beauty of what you have produced, and have a beer or maybe even
: two.

: 11. Plan on applying extra layers of glass before the first layer
: is fully cured so as to get a chemical bond. If the epoxy you
: use blushes, follow the manufacturer's instructions to avoid
: problems with it.

Pre-coating has certain advantages. One if you're using different woods they absorb epoxy at different rates, can make for resin starved areas which have no strength. Also it eliminates the possibility of outgassing which can make a real mess of your glass work. Also much easier, specially for new users, to control the amount of resin used when laying up the glass.

Bill H.