I am unable to fully saturate my fiberglass cloth =[

[yayeric]

I've been trying to waterproof a canoe with 6oz fiberglass cloth (weaved) with West Systems epoxy and special clear harder (#207)

Following the instructions, I put a bountiful amount of epoxy on the fiberglass, spreading it with a squeegee until the fiberglass becomes 'transparent' (I can still see it...). I then remove any excess.

My first coat is thin so that the fiberglass doesn't bunch-up and rise. Once that coat is tacky, I follow the same technique and place a 2nd coat on, followed by a third.

I have more than enough epoxy on this canoe to fully saturate the cloth, yet the fiberglass in the final product is seen through diffraction at certain angles. There are some areas where the fiberglass is 100% invisible. I can't for the life of me figure out what I did wrong. I used small batches, worked at a nice temperature, everything.

Any suggestions would be great, thanks!

[Pmullen503]

You may have worked some air into the epoxy. Nothing you can do now but a few tips for the future:

If you remove excess epoxy by scraping, SLOW DOWN. Moving too fast forces air into the epoxy. Also the epoxy you scrape off will have tiny bubbles in it. DISCARD it or use it with filler for something else if you are going for a very clear lay up. I use a cheap deck of playing cards so I can discard them periodically. The cards also limit how hard you can scrape; you just want the make sure the cloth isn't floating on top of the epoxy, not squeeze out the epoxy.

[tony.latham]

Once that coat is tacky...

I think that may be the problem. You may have wet the cloth out, and then the wood sucked up some epoxy, starving the glass. Adding more epoxy to tacky epoxy isn't going to saturate the starved cloth.

That's my best guess. I usually take a hard look at the layup after about fifteen minutes looking for white-ish areas.

Tony

[tony.latham]

Try sanding lightly between coats to smooth things out. Double-check your hardener-to-resin ratio too; small deviations can affect clarity. After your last fiberglass layer, apply a thin coat of just epoxy to fill imperfections. Also, keep your workspace dust-free to prevent diffraction.

Bot much????

[yayeric]

Thanks for the replies!

I probably am pressing to hard on the squeegee, to the point of permanent squeegee deformation.

I ran some tests with a roller and much better results. The fiberglass is invisible but still visible, similar to the alien from Predator.

Below an example of the shimmering shards I'm mentioning. The sharda are viaiblw on the left hand side, but not visible on the right.

Are these shimmers normal? They arent present in 100% of the cloth, and I'm trying to reduce the frequency they occur.

I'm trying to avoid them, for aesthetics purposes

[saywhatthat]

when you mix, do you get air bubbles? did you seal first how are you wetting out? when wet have you used a torch to pop air bubbles

[yayeric]

when you mix you get air bubbles? did you seall first how are you wetting out. when wet have you used a torch to pop air bubbles

Just to be clear, those 'shimmers' are beneath ~mm of epoxy - they are not exposed in any way. The surface is completely smooth to the touch.
There's always air bubbles, but I keep it to the minimum that I can. I'm following Tony Latham's book, placing dry cloth over clean wood, pouring epoxy and spreading with a high-density foam roller (works best so far for me). I tried wetting the board before hand with epoxy on test pieces, however the weave soaks up the epoxy and spreads itself out, pushing itself off the wood. Those were impossible to spread out afterwards without yanking on the fabric, which makes the trapped air only worse. West Systems recommends the dry application for pieces too, and I have to agree with them.

I am using a heat gun, however the trapped air in the weave (I'm assuming) cannot leave, the epoxy is too viscus. Heating the epoxy with a heat gun does decrease the viscosity and allow the trapped air to leave extremely easily, however the line between that and pushing the air out from the wood underneath the wood only makes problems worse. The heat does remove bubbles above the weave easily, but not below it.

I have thrown well more than enough epoxy on test boards and the epoxy doesn't have enough fluidity to displace the air. Tony Latham used 3/4 of a gallon on his build, and somehow I'm on gallon number 4 (I hate how much money I've spent....). I didn't have this problem with deep pours I've done on tables in the past, the depth of the epoxy has enough force from gravity to displace air. The foam roller, squeegee, or fancy metal roller don't seem to fill the weave completely.

I cannot find a single source online discussing this issue, so either I'm being too particular for my own good or I'm doing something wrong, probably a combination of things. Perhaps I bought crappy fiberglass for the job

Below is a link to the fiberglass weave I purchased.
https://fiberglasswarehouse.com/product ... style-3733

[Pmullen503]

MAS, RAKA, System 3 all make low viscosity laminating resin that will make it easier to get the result you want compared to West which is thick.

Even US Composites makes a low viscosity resin that's pretty good.

Warming epoxy with heat can actually make bubbling worse by expanding air in the dry wood that bubbles out.

The photo you show doesn't look bad. Close inspection, especially at certain light angles, might show some hint of weave. From a few feet away it shouldn't be noticable.

I was thinking you had cloudy, white patches. I bought a mahogany sailboat like that once, ended up just painting it.

[saywhatthat]

i wonder if the wood is so dry it drinks it up take some expoy add 2 to 5 % acetone mix real good precoat wood let set 3 are 4 days tell you can sand and no tacky resin then lay up . if you are using that much resin it soaking in your wood