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View Full Version : Yet another one - a beginner with an epoxy question



wwaterman
05-30-2007, 01:51 AM
Just wondering, and yes, I did search for the answer to this question on the board (but not nearly hard enough, mwah!):

I'm building a WGW and I'm fiberglassing the thwarts and breasthook. When applying the second "filler coat" (as described in the instructions), should I squeege the epoxy off after application (of the second coat)? I already did this, because I'd rather be safe than sorry - as I can always apply more epoxy.

After applying the second coat, it seemed nice the way it was, after rolling the epoxy on with a 1/8-inch foam cover. It seemed even and not too thick, but a nice coat that will withstand some use.

Thoughts would be appreciated.

-Will

JimD
05-30-2007, 03:12 AM
Welcome to the forum, wwaterman! The main thing is apply successive coats before the coat underneath fully cures. Aside from that the rules for application are whatever method works as long as you're happy with the result. I find the least wasteful way to go is always to apply thin coats, even if it means an extra fill coat. You'll end up with a fairer surface and less wasteful sanding. One undesirable situation to find oneself in is to have fully cured epoxy with the weave still unfilled.

Wild Wassa
05-30-2007, 03:31 AM
Another dupe post. JD I'm only backing up your post because no one was on the thread when I first posted.

Wild Wassa
05-30-2007, 03:32 AM
A nice looking boat to have selected Skipper.

Give the glass and epoxy time to cure and shrink. Then use the filler just to fill the slight depressions in the cloth's weave. Thining out the excess epoxy is always a good move, making sure your coats end up being uniform. Removing the excess epoxy helps to reduce the brittle by nature characteristic of overly thick epoxy coats. Adding the filler will do the same to epoxy.

You sound like you're on the right track.

Warren.

Wild Wassa
05-30-2007, 03:36 AM
Another duplicate post ... most bizarre.

wwaterman
05-30-2007, 11:33 AM
Thanks guys!

So, right now I can still feel the weave. As an end result, I definitely don't want to feel that at all, right?

"An undesirable situation is to have the epoxy fully cured and the weave unfilled"

The weave is barely able to be felt, but it is not "smooth like glass." I'm guessing I want to have it like that, eh?

James McMullen
05-30-2007, 11:00 PM
Filling the weave beyond the very brim is adding weight. . . .and cost. . .and time. . . . .
Too much epoxy is not really any better than not enough. With 6oz cloth I have usually found that the second or sometimes third coat rolled on is enough.

Definitely put it all on in successive layers without letting it cure too long between coats so you won't have problems with amine blushing and such.

Wineglass wherries are nice rowboats! Good luck to you on having your very own.

pipefitter
05-30-2007, 11:44 PM
The amount of epoxy applied, is relative to the finish desired,how fair the hull is to start with and how fair the glass is able to be installed and what kind of paint schedule one may be using. I have seen glass cloth print through sanded primer and two part paints when it was visibly perfect initially.Mainly due to having to build excess coats of primer/surfacer which shrinks more and for a lot longer than epoxy does. It should have enough epoxy coating to allow for near perfect fairing without burning the glass cloth so that the primer coat is minimal. A good primer coat would be nearly transparent ideally.I like to add enough coats of epoxy so that I can do most of the fairing and blocking there and spend minimal amount of time trying to prove it during the primer stage. It's much harder to spot blend epoxy when you find it is too close to the glass without intruding into the glass outside of the repairs that would have been fine otherwise.

donald branscom
05-31-2007, 01:19 AM
Thanks guys!

So, right now I can still feel the weave. As an end result, I definitely don't want to feel that at all, right?

"An undesirable situation is to have the epoxy fully cured and the weave unfilled"

The weave is barely able to be felt, but it is not "smooth like glass." I'm guessing I want to have it like that, eh?

If you cover the wet epoxy on the cloth with that plastic mylar and roll that down and leave it untill dry, the plastic will peel right off and be glass smooth. i tried it and it works.

Boatmik
05-31-2007, 07:35 AM
If using the roller you can get an extra smooth surface by preventing the roller from turning and lightly sliding it over the surface after the coat is rolled out.

Just slowly so the roller doesn't bounce or tear. The end result is that it pops all the bubbles and removes the last of the roller texture.

As far as fill coats go - fill 90 to 95% of the texture - a little bit of texture on the surface will sand down pretty easy to provide a flat surface without going into the glass much.

But peel ply can work too - provided the surface curvature is not too complex - I haven't tried Mylar - though it might not compound over complex shapes that the peel ply (being woven) can manage.

Best wishes
MIK

Iain Gower
06-08-2007, 07:37 PM
I have a similar problem with this fibreglassing trick. I have ended up with sections with not enough eopxy over the glass even after the second coat wet on wet. I am using Botecote epoxy which is made in Aus and needs to be lightly sanded after curing to key for the next coat. If I do this I will be tearing into the glass ie valleys only 50% full. Any ideas on how I can get the surface prepped up without damage to the glass. I get the feeling most of you guys are in USA and use West system which as I understand will take wet on cured epoxy. Not getting a response from the manufacturer.
Building a 40' Cat ply epoxy.
Regards
Iain

Cuyahoga Chuck
06-08-2007, 08:37 PM
I have a similar problem with this fibreglassing trick. I have ended up with sections with not enough eopxy over the glass even after the second coat wet on wet. I am using Botecote epoxy which is made in Aus and needs to be lightly sanded after curing to key for the next coat. If I do this I will be tearing into the glass ie valleys only 50% full. Any ideas on how I can get the surface prepped up without damage to the glass. I get the feeling most of you guys are in USA and use West system which as I understand will take wet on cured epoxy. Not getting a response from the manufacturer.
Building a 40' Cat ply epoxy.
Regards
Iain

The boogey-man we all face is amin blush. If the epoxy sets for too long there is a possibilty that the surface is contaminated with this by-product of the curing process. If amin blush forms the surface must be scrubbed with water to before another coat is applied. By applying additional coats "wet on wet" there is no danger of a poor bond. The amin blush will end up only on top of the last coat.
An additional benefit is you should not have to do any surface preparation between coats. When doing fill coats on hull exteriors the last thing you would want to do is sand into the glass. The glass contributes much strength to the hull and must remain intact to get the full benefit.
Wet on wet is widely used, particularly when hand laminating fiberglass canoe hulls. If any of the glass laminates don't bond the hull is junk. The procedure is to start early in the A.M. and keep laminating until all the layers are applied and the last layer is filled with a little excess to allow for light sanding. They keep going even if it they have to work into the wee hours of the following morning.
There are some epoxies that claim "no amin blush" but, if you use "wet on wet" their claims don't matter.

pipefitter
06-09-2007, 02:26 AM
I have a similar problem with this fibreglassing trick. I have ended up with sections with not enough eopxy over the glass even after the second coat wet on wet. I am using Botecote epoxy which is made in Aus and needs to be lightly sanded after curing to key for the next coat. If I do this I will be tearing into the glass ie valleys only 50% full. Any ideas on how I can get the surface prepped up without damage to the glass. I get the feeling most of you guys are in USA and use West system which as I understand will take wet on cured epoxy. Not getting a response from the manufacturer.
Building a 40' Cat ply epoxy.
Regards
Iain

Being you are having to work dry on dry though,unless the texture of the fibreglass is apparent thru the epoxy,which is really enough of a key in itself,you're going to have to sand it.Just break the glaze and don't maul the cloth. If you start to burn the cloth a bit,just make sure to atleast dull the surface. The strength of the glass is really most important near the joints themselves and if it's stitch and tape,there should be multiple layers there anyway so that a little surface scoring of the glass isn't going to hurt it. If there is depressions in the finish,go over the rest of it and go back and scuff those by hand so as to not blister the higher build surrounding it. Then just scrub/wash the surface with a coarse scotchbrite pad and plenty of warm water.If you wipe it down with denatured alcohol and plenty of clean/absorbent (paper painters rags)rags,you will feel a slight tackiness of the surface which will hold epoxy quite well. Just make sure you add a good coat to finally bury the glass.
I was in the same situation as you and I had emailed Paul Oman from Progressive Epoxy Polymers Inc. and he pretty much assured me that it would bond and it did. I have had no problems with the epoxy on my boat.

Iain Gower
06-09-2007, 09:05 AM
Thanks Guys,
The scotchbrite and the alcohol sounds like the trick. The eopxy I am using needs to be sanded once it has gone off to get rid of the gloss.. Made for Aussie conditions, very good but I was running out of light time and temp was at bottom limit for use. Thinned the epoxy to get me thru but am now paying the price. The epoxy does not get ammine blush which is good but needs the sanding. 90% of the hull is great but...for this portion.
Yep the glass is double bias two layers we call knitted as against woven.
Thanks for help.