: Someone recommended to me the other day putting a saturation coat on both
: sides of the sheets of plywood before even cutting out the pieces. He said
: that way you can do it while it's lying flat and avoid runs and drips. Any
: opinions about that method?

Hi Patsy

Here's what I did and why. I'm in the process of building ( epoxying ) my Rob-Roy canoe right now, and being my first glassing project, I followed the designers suggestions about this. I cut all my parts out and applied a saturation coat on both sides of the panels. I spread it with a squeegie and after setting a few minutes, maybe 15 - 20, I squeegied off the excess. I didn't leave anything on to puddle up. I wired the panels up to some rafters and the garage door so they were hanging and not touching anything while curing. As soon as it was cured enough, I used the R.O.S. and a 100 grit disc and went over it so there were no shiney areas.
If you don't get back to the stitching and seam filling within a few days you will only get a mechanical bond with your later coats. I've been working on mine over a 3 month period, so that is what I expect on mine. If I were to do it again, I would make sure I will be able to get back to it every night, or no more than 48 hrs. between coats until the glassing was done, or... just forgo the early saturation coat and do it before glassing.

That being said, now, I will say that I am glad I did it this way for my first attempt at glassing. The reasons being that when I was sanding my seam tapes to feather them into the plywood, I would have plenty of warning when I was sanding a bit too much on the plywood side, and before I sanded through the thin veneer of the ply. The epoxy is much harder, as is the glass, so it would have been very easy to sand through the ply layers in trying to get the tape feathered. As it was, I only had one place where I got carried away and that's on the bottom of the boat, and I will be painting the bottom, below the waterline, white, so that didn't matter. Also, the problem with possible blotches where you sand through the resin ( saturation coat ) and later coat the entire boat with epoxy aren't that visible. In fact, I have yet to notice any, but with the Okoume plywood, the color has it's own color variation that will probably obscure most or all of that anyway. I don't think it's an issue either way, since you are going to get some resin on the plywood while taping either way, and if there is actually any possibility of blotching you will have it there anyway. ( that's if you forgo the saturation coat at the beginning )
And lastly, the saturation coat does, in affect, help stiffen up the plywood where it is being bent and twisted around. In my case, there is a cut into the plywood where the bottom and side of the boat are of the same piece of plywood and bend a considerable amount at that cut. I don't think that the plywood would have withstood that torque without the resin saturation coat. It goes from a 90* side/bottom joint to the round and then flattened shape at the stems and all within around 5 or 6'.

: The concerns that come to my mind are one, that the building process is going
: to sand some of it off so there will be places with no saturation coat
: when you get ready to glass, possibly creating spots of starved glass; and
: two, what effect would it have on having possibly months between the
: saturation coat and the glassing? I guess you would need to lightly sand
: the saturation coat between fully curing and before applying the glass?
: Patsy

In preperation for my glassing, and some during the taping procedure, I did sand through the resin ( saturation ) coat in a few places. I am using RAKA 127/350 resin/hardner combination and their satin 3.25oz glass. The satin weave glass is a bit more difficult to get saturation, as I have heard, but with their resin, I had NO problems what so ever. It is a matter of what you are used to. I have watched friends using West System ( and others ) that are a bit thicker, and applying over standard cloth and I didn't see that it was any harder or easier either way. Maybe applying their epoxies over the satin weave would be more difficult, but as I mentioned, it's all a matter of what you are used to. It took a bit longer for me because I was a first timer, but my batches are taking approx. 1 hr. or so ( in 50* avg. weather ) and I've had more than enough time to work it. When I warm the garage up to over 70* it goes about 45 minutes, but is still plenty of time. I didn't have any visible areas where the glass cloth looked starved, but if you do, there is plenty of time to look over the boat and simply apply some more resin to those areas and sqeegee it off before anything sets up. Not to worry!

Best case scenerio is: You have nothing better to do for two days, when it comes to glassing, and you start one afternoon when the temp. is at it's peek for the day, saturate, squeegee, let that set, then glass the boat that evening.
Next morning when it's set, start your fill coats. My canoe buddy, here in Fresno, glasses four boats at a time in two days, start to finish. ( outside only ) But, he does it for a living and always clears his calendar and works from sun-up to mid-night. He is very anal about checking it every hour or so for runs and so forth. He also has a temp. controlled shop. But then, he gets Joe Greenley Grade boats too!!

When you order your glass cloth and epoxy kit from RAKA, take the time to talk to Larry Steeves. He's the boss and does all the phone orders, and if you are new at this, he will ask you to call ( if you email your order ) him and discuss it with him. He's very good at what his products will do and how to used them to full advantage. He is very accurate at calculating your needs as well.

As I mentioned, I think you should go ahead and do the saturation coat first, then sand it and go on with your project. The mechanical bond is not a bad thing. The chemical bond is just better. You will get used to it in whatever fashion you choose and you will figure out what you like and don't like about it, and may change the procedure as you feel is best.

Hope some of this helps!

Rehd