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NDR: fiberglass wet out failure on canoe

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NDR: fiberglass wet out failure on canoe
Hello!
I?m in the process of restoring a 13? Stowe canoe that was rotting away on the other side of town. These canoes can be very nice when done and being lockdown season, I needed a project to chew on. Fast forward and after pecking away at it, it?s time to put in a fiberglass matt to stiffen the hull. This is an important step for these canoes as it provides stiffness and protection for the thin ribs from general knee and foot traffic .
Long story short, the mat (.75 oz) turned milky white and did not clear with the application of west systems epoxy. I have not had this happen before (and I?ve glassed a bunch of stuff) so after thinking on it a bit I pulled up the cloth and tossed it. I?m gearing up for another run at it. Any thoughts on what caused this? Wondering if I should switch to a poly or vinyl resin for the
next go around. I understand they are less prone to outcomes like this.

Thanks for any ideas you have.
Jamus

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Re: NDR: fiberglass wet out failure on canoe In reply to
Good morning, Jamus~


I think your problem is the mat. Most mat is chemically incompatible with epoxy resin. There is a binder that holds the fibers together in the mat that is the problem. It works with polyester resin but not epoxies.


I know that mats are made that are compatible with epoxy - but have never used one.



On the other hand, the mat attached to the double-bias (biaxial) rovings in the 1708 I often use IS compatible. I think these are epoxy-compatible because the mat fibers are stitched to the rovings. Would that work for you?


I get most of my 'glass supplies from U S Composites. They offer a lighter (12 oz v 17 oz) biaxial - DBM 1208.



http://www.uscomposites.com/specialty.html



You may want to call their tech support folks.


Hope this helps.


SJS









Steven Jay Sanford
Pencil Brook Farm
South Cambridge, NY
http://www.stevenjaysanford.com


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Re: NDR: fiberglass wet out failure on canoe In reply to
High humidity is most likely the cause for the issue. In the coatings industry it's referred to as an amine blush...or as this quick search resulted in:

The cause is most likely due to a side chemical reaction of moisture (humidity) in the air, interacting with a curing agent. This phenomenon is known to epoxy chemists as ?amine blush? or ?amine bloom?.
SHE THINKS MY DUCKBOATS ARE SEXY
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Re: NDR: fiberglass wet out failure on canoe In reply to
Thank you both for the response. The issues that you both raise seem to be consistent with information that I have been researching and receiving. My plan of action will be to sand out all evidence of this first attempt and reload with new mat and poly resin as we get later into the fall (when humidity will have dissipated as well)

Appreciate the time and information gentlemen!
Jamus
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Re: NDR: fiberglass wet out failure on canoe In reply to
Jamus wrote:
Thank you both for the response. The issues that you both raise seem to be consistent with information that I have been researching and receiving. My plan of action will be to sand out all evidence of this first attempt and reload with new mat and poly resin as we get later into the fall (when humidity will have dissipated as well)

Appreciate the time and information gentlemen!
Jamus


I'd get some epoxy compatible mat as Steve said. Why use poly when epoxy will be better in the long run? I don't see humidity having anything to do with wet out, but it sure does affect blush (but blush is clear and on the surface and happens after the cure).
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Re: NDR: fiberglass wet out failure on canoe In reply to
Are you after adding strength to the hull? Or just cosmetics? Also what will you be finishing with? Paint? Gellcoat? Nothing?

If going for strength then I?d use 1708 with Epoxy. It will bond better to the wood and be strong but might require some fairing to cover the weave. Woven cloth can also be used and with a few coats of epoxy should look clear if no finish. CSM is more of a cosmetic mat and typically can?t be used with epoxy because of the styrene in it as binder. So poly it is for that but if you?re going over the wood before to saturate that good and heavy so that the wood soaks up what it wants before laying the mat.

Also the laminating poly resin needs to be finished with wax or pva before finishing.

If just for a clear Cosmetic look why not just a few coats of epoxy and no mat over the wood?

Hope this helps.

Last edited by:

Tom Barb: Sep 17, 2020, 6:35 AM
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Re: NDR: fiberglass wet out failure on canoe In reply to
thank you all for the comments. The purpose of the mat, per Merrimack canoes, is to protect the ribs (which are decorative and only 1/16" cherry) from point loads and to provide stiffness to the hull. They are intended to be clear through the mat, and to look pretty. I was informed that the mat will give more strength and rigidity than woven cloth. I would rather carry forward with epoxy and not have to sand out what's there and I would like it to finish clear. I called US Composites and they did not have a clear epoxy that would do this, only amber, and the poly would not stick to the epoxy presently on the boat. So I find myself at a sight impasse. Sounds like there's an epoxy compatible mat though, so I'll need to look into that.

Thank you all for the responses!
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Re: NDR: fiberglass wet out failure on canoe In reply to
If one of your goals is looks I would think the biax or woven stuff is gonna show and be sort of weird compared to chopped strand mat which could be applied in layers to retain a more clear skin over wood.

The guys are right about humidity. I get milky spots when sweats drips, but it cures fine and they're small. Humidity or moisture in the mat could be it, but like the guys mentioned it's more likely the epoxy & CSM combination. You can get clear epoxy, I would call around or check with other suppliers. Obviously these materials are gonna cost ya some money so call more places and ask their technical people your questions. You could call Fiberlay in Sarasota, FL. I've seen clear epoxy there even though I don't use it. They ship stuff, have a website, and might be a resource. It could also be worth getting a small kit and doing a few tests. Then buy more of what you need based on the experimentation.

My .02 cents...