Epoxy/Glass issue

[sailsman63]

So, I've had a summer to digest what I learned from my experimental build last winter/spring, and overall, I think I'm ready to improve on the next one. Many things went right, many more went wrong and were corrected.

Then, there's this:





I'm very disappointed with the way the interior glass turned out. the cloudiness is not just dust. The camera exaggerates, but not much. I only got six or seven full days on the water. Here's the specs for the surface:

• Single 6oz e-glass
• Wet-out was System Three clearcoat
• "Partial fill" - added a couple of layers of resin, but did not try to fully fill the weave - wanted a little tooth in the surface. System Three Silvertip resin.
• Three coats System Three wr-lpu (Very odd stuff. Love it for some things, hate it for others)

Observed properties

• Some of this is very near the surface. When I sanded to get some tooth for the cleats, the finish improved quite a bit.
• Some is very not near the surface. Down the center, sanding had no effect - the cloud remained.

Possibilities:

• UV breakdown. Seems logical, but the outside of the hull has the same layup and finish, has racked up even more sun exposure (driving around on top of my car) and does not show this flaw.
• Scuff damage. I've found that the partially filled weave tends to trap the local river sand-silt mix. I've had to use a stiff brush to get it out at times. Does not match with the fact that some of this is definitely below the surface
• Amine blush or other resin cure issues? But then, why did it not show up in the original build? I've gone back and checked the pictures.

It's bad enough that I'm tempted to score the glass about an inch and a half below the gunwales, peel it off with a heat gun, and re-glass. Before I do that, though, I'd like to know what went wrong, and how to prevent it. I also don't want this to happen to any new builds...

So.... Any experienced epoxy guys and gals out there that recognize this set of symptoms? How can I check?

 

[memaquay]

It won't be UV breakdown unless you left the open hull in the sun for a few summers. It's hard to tell from those pics, but it kind of looks like sections were either starved of epoxy, creating the whitish patches, or you had a case of amine blush. Was your work space damp and cool when you did the wet out?

My feeling is that if you give it a general sanding and apply three coats of varnish, it will come back to life. Did you varnish the inside hull?

 

[frozentripper]

Memaquay,

Was your work space damp and cool when you did the wet out?

The first time, yes... the epoxy turned milky. The people at Noah's Marine after seeing a sample said it was epoxy absorbing water, not amine blush, and advised 20C/68F or higher with low humidity. Also sand off the milky layer which should only be on the surface of the epoxy and that worked. So for the interior glass the wood stove was going pretty hot and so was the dehumidifier with temps about 25C.... that glass cured nice and clear.

Sailsman,

• Some of this is very near the surface. When I sanded to get some tooth for the cleats, the finish improved quite a bit.

Maybe sanding would remove most of the cloudy surface layer? Might be worth a try... good luck.

 

[sailsman63]

The thing is, I've tried sanding. The close-up in the center is after a sand and re-finish. Part of the issue here is that the weave was never filled, which means any sanding is actually going into the weave.

The inside was top-coated with a linear Polyurethane, System-Three's own, recommended, UV blocker. The same finish is holding up well on the outside.

I don't think it was resin starvation, as this did not show up immediately.

The shop would have been cooler than I liked - it's unheated except for a barrel stove that we only run when we are actually out there. I did make an effort to bring the temps up before doing glass work, and as it was winter, I would expect the RH to be around 20-30%.

Epoxy, absorbing water? Presumably before it was fully cured? Sounds a lot like amine blush, happening down under the surface.

 

[sailsman63]

Reviewing more of my photos - this did not show up anywhere near the time that I glassed it, and even the finishing steps looked good. Its got to be some kind of wear damage, which I find really frustrating, since I haven't used the canoe all that hard.

Raw wet out, while fitting gunwales:


And the day I put a finish on it:


Any ideas on how hard it might be to strip just the inside glass? I'm not interested in ruining the outside.

 

[Guest]

Possibilities:

• UV breakdown. Seems logical, but the outside of the hull has the same layup and finish, has racked up even more sun exposure (driving around on top of my car) and does not show this flaw.
• Scuff damage. I've found that the partially filled weave tends to trap the local river sand-silt mix. I've had to use a stiff brush to get it out at times. Does not match with the fact that some of this is definitely below the surface
• Amine blush or other resin cure issues? But then, why did it not show up in the original build? I've gone back and checked the pictures.

It's bad enough that I'm tempted to score the glass about an inch and a half below the gunwales, peel it off with a heat gun, and re-glass. Before I do that, though, I'd like to know what went wrong, and how to prevent it. I also don't want this to happen to any new builds...

So.... Any experienced epoxy guys and gals out there that recognize this set of symptoms?

UV breakdown does not seem likely given the limited amount of exposure and the difference with the exterior of the hull.

Scuff damage does seem likely, at least with the stuff above the surface. The bit of non-slippery “tooth” left on the interior vs the uncloudy exterior could be an indicator.

Amine blush is a good possibility, but blush has usually been apparent as a greasy to the touch film. And in any case if I am not doing another epoxy coat immediately I am usually waiting and sanding next, and then washing and drying the hull to rid the sanding dust before doing any topcoat.

Even if I am not sanding I tend to wait for any blush to appear or outgassing to resolve, and then wash and wipe before I varnish or paint over epoxy. Most of my epoxy and glass work is with (sometimes extensive) repairs, but in simply rehabbing a composite boat I probably wash and wipe it four or five times over the course of a rebuild.

OK, actually like 8 or 10 times. I wash it twice each time, using clean water and a new, uncontaminated Scotchbrite pad for the second scrub, so I’m less likely to be smearing any residual sponge or bucket blush around.

Resin starvation? That might not be as immediately apparent and might account areas of under-surface cloudiness. I have an admittedly heavy hand with epoxy wet out and fill coats. Could the raised tooth have been scuffed enough to allow water infiltration into (and under) resin starved glass?

How can I check?

That might be the most important question.

How does the inside look when it is water wet? Do the surface “scuffs” disappear and the under-surface clouds remain when the inside is dampened with a wet sponge?

Maybe do a couple discrete areas of test top coat with varnish or more epoxy fill, with and/or without light sanding?

The real builder folk here may have better how-can-I-check diagnostic ideas before ripped out the interior glass.

It is still a beautiful canoe, and I’d hate to go through ripping out the glass, sanding and reglassing, especially if some topcoat would largely resolve the cloudy areas.

 

[sailsman63]

Good ideas.

I've already done some sand, fill coat, topcoat testing in conjunction with installing my seat cleats, which went in after this issue showed up. Some of the obvious surface scuffs were cleared up, but the cloudiness remains.

When water-wet, the scuffs are much less noticeable, but the cloudiness is still there.

It would be possible to have a layup that appeared water-clear that was still resin-starved? That would be news to me.

I'm not one to over-do resin, but I thought that I had it well wet out. I was using a fairly low-viscosity resin. I suppose that the cedar may have continued to absorb more after wet-out, or it may have flowed under and lifted the glass a bit, as well. When doing a peel-ply experiment on a paddle, I was surprised at how many areas appeared to need more resin after a few minutes of resting.

The scuffing on the texture has definitely been deep enough to reach fiber. If that fiber was starved, water infiltration seems likely. In fact, some of it may have come from the topcoat itself, which is water-based. (Like I said, odd stuff.) I'd assumed that the glass was fully saturated, so I did not even consider the possibility that anything could wick in along the fibers.

 

[stripperguy]

It does look like a starved wet out, but it's surprising that it didn't show up immediately.
If you glassed over bare wood, the wood can suck out resin from the cloth, leaving cloudiness and a weaker laminate.
Some resins are more sensitive to humidity levels, System 3 and West epoxies are known for that.
Could that be delamination due to high stresses?
Stripping the glass from the inside would be difficult and likely you would lose quite a bit of your substrate.

My nephew had a few spots similar to yours on his 3 year old build.
What had looked like an ideal wet out on his outside, eventually developed some cloudy spots. He cut out those spots and I helped him patch them.
He said each of the spots were solid and hard at the surface, but actually soft next to the substrate. We concluded that he had one improperly mixed batch of resin.

 

[frozentripper]

I can't tell from the photos, is there any cloudy epoxy next to and under the inwales where scuffing would be unlikely... I checked West Epoxies FAQ on cloudy epoxy curing and water/humidity can be a problem with their epoxies.

PROBLEM: Clear coating turned cloudy.

POSSIBLE CAUSES & SOLUTIONS:
Moisture from condensation or very humid conditions reacts with components in uncured hardener.

Apply moderate heat to partially cured coating to remove moisture and complete cure. See Out-Gassing caution in User Manual.
Use 207 Hardener for clear coating applications and for bonding thin veneers where epoxy may bleed through to the surface.
Entrapped air from aggressive roller application.

Apply coating at warmer temperature--epoxy is thinner at warmer temperatures.
Apply epoxy in thin coats.
Apply moderate heat to release trapped air and complete cure. See Out-Gassing caution in User Manual.

http://www.westsystem.com/ss/faq-problem-solver/#cloudy

It is a really nice hull and peeling off heated fiberglass might damage the looks so my inclination whatever the cause(es) of cloudy epoxy actually is/are, would be to sand off as much cloudy glass and epoxy and topcoat as necessary to remove the cloudiness and then if the sanding removes some of the weave, apply another glass layer maybe with a lighter weight cloth. Seems like less effort than heating and peeling and then sanding even more, and safer after all the work that went into the build.

 

[Jim Dodd]

At this point, I'd say live with it. Give it a coat spar varnish. If that doesn't work. Again live with it.
​ Removing the inside would be a major chore !!!

​ Next build ?
Glass when it is warm outside. I used to glass mine in July.
I used foam rollers, and filled the weave on the inside. I NEVER sand between coats ! Once I start filling the weave, 1-2 hrs later, I'm apply another fill coat, until I'm done with filling the weave ! No problems !

​ Epoxy and cold don't mix. That goes for storing epoxy too ! Store at room temps if possible.
Glass when it's WARM ! I've been there, and done that !

You've gained a lot of knowledge with this build ! You're next one will be better, I can almost guarantee it !

Jim

 

[Will Derness]

At this point, I'd say live with it. Give it a coat spar varnish. If that doesn't work. Again live with it.
​ Removing the inside would be a major chore !!!

Jim

That advice encapsulates the operating principles of Slacker Boat Works - the locus of products and efforts that come out of my little shop. I'm just average in skills and tool sets, so imperfections are common outcomes. When faced with a big intervention, I tend to shrug my shoulders and move on.

However, I understand being tugged the other way - that is a beautiful craft.

 

[wysedav]

It might be your top coat, on my last canoe I used some waterbased clear coat which looked beautiful until I put it in the water. Then it turned milky everywhere that got wet. It doesn't really go away when rewet, only a little better. I'm living with it, one of these days I'll fix it up.

 

[Alan Gage]

I've got something similar going on with the outside of Bloodvein 2.0. The exterior is black (fiberglass over carbon) and when doing some touch up work in the shop this winter I noticed that the entire hull seemed more grey than black. This was confirmed by looking at pictures from when the boat was originally completed although even then it wasn't pure black.

At first I thought it was just on the surface but when I sanded the bottom of the hull for another epoxy application to fill some scratches it made no difference. Wiping with alcohol or water makes no difference either. The problem isn't just apparent on the bottom of the canoe but comes up the sides. It isn't uniform and looks like surface contamination but it doesn't wipe or sand off. The outer layer of fiberglass isn't a full layer and this is where the problem seems to be most apparent; though it does extend to the rest of the hull as well. When new the outside was given a few coats of Helmsman Spar varnish.

I've never noticed this on any of the my other boats but the outer layer on this one was starved for resin when I laid it up. I laid up about 4 layers of cloth at once and then put peel ply over the top. It was starting to gel and I got a little carried away with the squeegee in an attempt to get rid of excess resin. When I pulled the peel ply I found the weave full of pinholes.

20160104_006 by Alan, on Flickr

20160104_009 by Alan, on Flickr

When I added more epoxy it sucked it up like a sponge and got rid of nearly all the air holes. This picture is a closeup of the transition line between plain carbon and the 6oz. S-glass layer at the water line.

20160405_003 by Alan, on Flickr

But the color never did seem as black as it should be and now it appears to have gotten worse. I don't know but am guessing that the starved cloth is at the root of the problem.

Like Jim and Will suggested I'll just shrug my shoulders and move on.

How cold was it in the shop when you were applying your epoxy? I've fiberglassed hulls in the mid-60's before but I keep it over 70 now (75 is better) and have the shop warmed up long enough ahead of time so that the resin is fully heated too. The thicker resin does not soak into the cloth as well. Not only that but it seems like the small bubbles escaping from the wood can't flow to the surface through the thick resin and become trapped. I often don't notice these unless I look closely. Sometimes I don't notice until I sand the hull a little and I start cutting into those little air bubble pockets. I've found the warmer shop makes a big difference in how easily the cloth wets out and how many bubbles are trapped in the laminate.

The same thing can happen if your resin starts to kick. I don't realize that it's beginning to thicken until I notice the cloth not wetting out properly. At a quick glance it looks like it's turned clear but looking closer I can still make out the pale color of the weave in spots. No matter how much I dab at it that kicking epoxy won't quite soak in all the way.

Whether or not any of these are the cause of your problem I don't know but those are a couple of my personal experiences. It's a shame to have that interior finish mar such a beautiful hull but the thought of trying to peel off the fiberglass and redo it would be enough to make me puke. I'd rather spend my time building another hull.

Alan

 

[sailsman63]

Thanks all for the replies.

There's no way that I would be able to sand through this without taking off most of the thickness of the glass, if not in fact going down to bare wood. I think that at this point, Jim Dodd probably has the practical idea. I may try topcoating again, but that would be mostly to clean up the known scuff marks, and try to prevent further damage in that way...

wysedav I really don't think this is the topcoat alone. Its kind of hard to see, but most of the "cloudy" is way deeper than the finish went. Plus, the same topcoat on the outside looks fine.

Alan Gage I remember when you pulled the peel ply on that. Is the upper photo recent? You seem to have a better camera or lighting. That is very much what I see, though more evenly distributed. I'm wondering if what we are seeing started as micro-voids, so small as to be invisible. After some time, with the composite being placed under load, (use in my case, perhaps just being rolled over a few times for you - or even slight shifts in internal stress due to thermal cycling) these spaces might open up to an extent. Just a theory.

I don't actually have a record of shop temps from the layup - I really should keep a journal of that. I remember that I was aiming for a minimum of 10 degrees above the minimum listed on the bottle for whichever resin I was using that day, which was a bit of a project.

stripperguy I don't think that this is a high-stress delamination. I've had that due to a mishap. You can usually see the weave lines very clearly - A series of sharp hashmarks. Any discrete "point size" in the cloudiness is to small to be seen with a human eye. I may well have had mixing issues, something to watch more closely in the future.

 

[memaquay]

I know you don't think it's the top coat, but I used a water based varnish once. I t went on cloudy, almost milky like, and never did dry to the same gloss you get with oil based products. In the field, after being wet for a day or two, the cloudiness returned. I sanded it all off and went back to oil based products.

Trying to remove epoxied glass from a hull is verrrrrrrrry difficult. I attempted it on one of my old strippers, using a heat gun first, then a blow torch. It was not a pretty sight, I quit after about two feet.

 

[Alan Gage]

Is the upper photo recent? You seem to have a better camera or lighting.

All the pictures I posted were from the building process. I don't have any current pictures showing what's going on but I'll try and remember to take a couple. My shop is well lit but I think a lot of the problem with your pictures comes from the on-camera flash. On such a large and long subject like a canoe it will be very difficult to get even lighting by using it.

I know you don't think it's the top coat, but I used a water based varnish once. I t went on cloudy, almost milky like, and never did dry to the same gloss you get with oil based products. In the field, after being wet for a day or two, the cloudiness returned. I sanded it all off and went back to oil based products.

I had the same results from using a water based spar varnish. I won't say the problem isn't in his top coat, because I don't know, but I will say that the System 3 WR-LPU that he used as his top coat seems to be a different animal than the run of the mill water based finishes. I used it (WR-LPU) once when refinishing the outside of a canoe and I didn't have any problems with it turning cloudy or soft like the other water based stuff. The canoe where I did use the regular water based finish was the one I took on my 30 day Bloodvein trip and despite the hard use I didn't notice any issues with the finish at the end of the trip; though my boat's interior wood is considerably lighter in color so it wouldn't be as apparent.

Alan

 

[frozentripper]

The only other thing in the past for me has been old epoxy (several years old) going cloudy after curing and that's probably not the problem here. That was on a dark black walnut paddle and easy to sand off (I was going with West Epoxies' most durable finish rec of finishing wood with epoxy and then varnish, to reduce the possibility of varnish going brittle with time and the need for re-varnishing).

 

[pblanc]

It looks like water spotting or water blush to me. Some epoxies are more prone to this and I have had System Three Clear Coat water blush even after fully cured so I usually cover it with varnish to prevent it.

If you haven't already tried, you might go over the surface with an acetone rag. The vinylester resin that Bell Canoe used for many years was notorious for water blushing many years after cure, but it could be made to go away temporarily by wiping it with acetone. If that worked for you I would then try applying another top coat of epoxy, then varnish before any water exposure. Water blush can sometimes be improved with local heat. You might try wafting a heat gun carefully over a small area.

High ambient humidity and slow cure rates (usually a result of low temperature) greatly increase the risk of water blush. Fiberglass cloth also absorbs atmospheric humidity so it is best to use fresh cloth for any build that will be clear finished, or protect the cloth rolls from atmospheric moisture by keeping them rolled up in plastic during storage.

 

[Jim Dodd]

Fiberglass cloth also absorbs atmospheric humidity so it is best to use fresh cloth for any build that will be clear finished, or protect the cloth rolls from atmospheric moisture by keeping them rolled up in plastic during storage.

Using fresh cloth. I was told years ago that fiberglass cloth ages, and use it with in a year of purchase. But I have used old cloth, that I couldn't see a difference.


I need to dig out some real old stuff, and experiment with it.

​Jim

 

[pblanc]

Old cloth might work fine. Or it might not. In addition to the possibility of absorbing atmospheric moisture, the "sizing" on fiberglass cloth that promotes resin absorption might deteriorate over time.