I posted elsewhere for some info on this for how best to work with epoxy when glassing overhead.............more thoughts and opinions are welcomed.
I have already been in the process of bonding together the hull & deck of my Magnum with Vinylester & 1708 (very good sticking power overhead) I switiched to epoxy for better adhesion & strenght in the areas that are harder to get to that can't be sanded & prepped very well.
I'm using systems three epoxy (med. cure) with DB stitchmat .........I tried pre-wetting out small 8" pieces to place overhead, but the epoxy runs and doesn't stick in place very well...........I already wasted a few pieces and cooked a qt. of epoxy because it's taking to long to fool with...........Do I thicken for better adhesion?........with thix. powder?.......what about the surface to be fiberglassed?.........do I pre-coat overhead before the fiberglass is applied?.............Thanks very much.

well first off you need to alter some of your products a bit and there are a few techniques that will help. The key to laminating overhead is balancing the laminate with resin. The most common mistake is thinking more epoxy will help it stick better when in fact that will make it fall easier. Adding a little cabosil to the epoxy will help keep it in place as well. When i laminate overhead i also skip the step of pre wetting the surface, seems to help balance out the laminate a bit further. I will wet out my pre cut patterns on a piece of cardboard and squeegee out excess resin then carefully roll them up. Rolling them out on an overhead surface takes some practice but i have been able to do pieces as large as 50" x 24" by my self. Another thing you need to do is dump the stichmat, mat really has no place in an epoxy system and can actually weaken the laminate. You should switch from 1708 to 1700 as well, its easier to work with and way easier to wet out. 1700 will give you a stronger piece and much lighter then any stitched mat system. Believe it or not when i laminate overhead i get little to no epoxy on me either. When i get in a boat to layup overhead the bulk of my balancing and wet out has already been done outside the boat and it takes only a few minutes to install the material and i rarely need to bring a bucket in with me. Weigh the cloth if you can and shoot for a 50/50 ratio. If you still have my number feel free to call me to elaborate on this. When i get back to my office i will put an illustration together on a technique for staggering in large laminations, its a method i use to do very large sections that allows you to do two layers in a single pass.

Hey Dave,

I mispoke when I said, I'm using a stichmat. I'm actually using a 12 oz. double bias cloth (Kyntex) ...........I was told it would work well (Merton's) with epoxy. I think your right though, I might be wetting out to heavy for somethin to stick overhead. The added problem is the surface is not flat. bonding the hull to deck spans like a squiggly line of S curves. It goes from overhead (underside of deck) to then, fitting the piece of kyntex around the inside piece of the wood for the rubrail, to then lastly, curve out and down a bit to complete the bond on the hullside.
Dave, I believe you said you were going to do the same (bonding hull & deck)) to your Magnum one day. I appreciate all the help and think smaller pieces might be the way to go at this point.......I also can see your point of a poor wetting out problem with the colth when using a thickened epoxy. Thanks

It actually surprises me that so many suppliers recomend any fabric with a stitched on mat for use with epoxy. Yes it will work but not only does the mat make it a pain in the azz to wet out and form but technically it becomes the weakest link in the system. It soaks up way to much resin, is difficult to form and because of the random nature of the fiber it offers no where near the physicals of just the bi laminate. Yes you can us it but you would do yourself a huge favor in getting a 1200 or an 1800 bi-ax.
over wetted laminates will definetly give ya fits when working vertically, I have done three and four layers as well as baltek coring and epoxy upsidedown without any trouble. Balanced laminates timing and choice of meterials are critical.

Dave I was able to get the first course layer up with no problem. First I mixed some thickened epoxy and placed it on the surface to be glassed, then I wetted out a piece and it held pretty good. The cloth I'm using has no mat attached to it, it's 12 oz. bi-axial somethin like 1708, but without the mat attached. Here's some picture of the area I'm glassing - 2 pics before and 1 pic after the first course........it's alittle rough, but I'm geting there.

Skip, are not roughing up the area with any sandpaper? just going over the gel or paint? I dont use epoxy but when i use poly or vinyl ester a always get down to the glass with 36 grit,your area may be to slick and the epoxy has nothing to bits in to and that could be why it falling on you..

Yes that's the cloth you want a matless bi ax, perfect. Like fixx said that area must and I mean must be sanded and 36 grit offers optimum adheasion. Its also best to get through and gel that was layed on there. Epoxy relys 100 percent on the mechanical bond. Upside is it you did not sand that area first the stuff you put on will pop right off with just a little help from a screwdriver

You should also try and do all the layers of your lamination at the same time. You can wait till each layer starts to gel before you put the next layer on but its best to do epoxy wet on wet otherwise you will have to sand between each layer

Fix,

It's roughed up to a degree, but not down to the pure laminant......I was looking for the most tenacious bond on an area that is poorly accesable and with mimimal prep....."Epoxy"
The deck is completely joined to the hull with SS bolts & nuts.......that might be good enough, but I wanted more. I want a second chemical resin bond completely around the inside lip of the hull & deck to be completely glass sandwiched. Some areas will be better than others when it comes to the mechanical bond issue........on the whole though this mag will be rock solid and that's what I want when she comes out from a stuff

Dave,

how far off til you undertake glassing hull / deck on the sport...........I'd like to be around for that one

if its not sanded it will have zero bond, epoxy only has mechanical. Get in there as best ya can even if you have to scrub it by hand with 36.

i wont be even thinking about doing anything to the Mag till winter at best.