Canoe mold - Awlgrip first, then layup glass and epoxy?

I've tried to research this but can't find much out there.

I have a female canoe mold that I am wanting to add a colored topcoat to the final product.

Been on the Awlgrip site and just not much there to help me.

Can I just roll a couple of coats of Awlgrip, let dry, sand lightly, then apply my glass with epoxy?

Is there another product I should consider?

My only goal is to have a fairly durable top coat on my finished product without having to spray.

Thanks...Alan

 

...emmm, what you have is a standard boat mould (female)...all you do is apply a coat of gelcoat of the colour you wish, then commence your standard layup for the job, when it is released, the gelcoat is (of course) on the outside (as it was the first layer in), so it will be finished naturally.

What you have to do is to polish your mould with a buffer (if necessary), then hand layup multiple coats of wax. It is this wax that will allow the boat (male) to be released from the mould(female). You do multiple coats of wax, say about 5 to 7, always wiping off the previous coats carefully with clean dry cloths. What happens is that the wax builds up, it creats a layer on the female mould so that the gelcoat that you are going to apply does not stick to the mould when being released.

As you are doing the layup in epoxy, you will be using the same for the gelcoat, that is, an epoxy compatible gelcoat.

 

I've done a lot of research and have found very few comments from people who say use gel coat.

I'm certainly willing to try that but I have looked far and wide and I have not found an affordable epoxy-based gel coat.

For a mold release, I'm used a teflon product from Airtec.

Alan

 

just use vinylester gelcoat and epoxy will stick to it.
comon in small race boats even Mumm 30's were built like this

 

Normal VE gel coats weather poorly, they turn yellow and chalk rapidly when compared to a polyester gel coat.

This product is designed for epoxy and will hold up well. You can buy it at Composites One.

http://www.ccponline.com/includes/PDFs/ECT120, 1.11.pdf

 

Then you must have been buying rubbish

 

Poor weathering of normal VE gel coat is just a fact.

 

Doug Lord
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Epoxy Layup: Paint in the Mold
After writing this for another thread I thought it might be interesting for others as well:
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I've done this a lot on small parts-rc sailboat hulls to 6': wax with partall#2 and POUR not spray PVA in the mold. If done right in a clean room(with a clean recovery receptacle) the PVA will come out wih no imperfections and a gloss the equal of any wax.The part should be poured nearly vertically and left that way until the PVA sets. I tried using "High Temp" wax with no partall but because of the trace silicones it fisheyed-I'm fairly sure a good wax with no silicones would work as well.I then spray a Rober(Italian) primer or Imron into the mold(depending on whether or not the flange has to be finished); after about 30 minutes the hull layup can be completed(epoxy only) and the boat pops out with a first class paint job(or ready for one) weighing 65% less than gelcoat. I believe most polyurethanes that are catalyzed will work; epoxy paint will not work.
I even tried using Krylon(older formulation) and it worked perfecly!
Should work on larger parts. If you're going to spray primer in the mold you can spray the PVA-just takes a little 600 to get it ready for paint after the part is pulled. But if the flange doesn't require finishing spraying the Imron works like a charm as long as you lay up before 1.5 hours more or less. If you wait too long the epoxy and paint don't bond well.

 

Same experience here, with other 2-pack PU paint. Just keep in mind the overcoat window. 1.5 hours is considered long already.

The customer using this technique is not using PVA, by the way. Just wax.

 

There was talk that Duratec primer can be sprayed in mould , then epoxy will stick to it and can be wetsanded for 2 pack paint adhesion , what you are wanting is a dream for most laminators. Other methods invole too much labor and $$$ of course you can try awlgrip in your mould ....and maybe ruin it ?

 

Is bad poly still better good VE?

A quick look around the boat yard at out club here with 70 odd beach cats show the AHPC boats from oz that are all VE look as good (at 10+years) as new or will with a buff compared to the hobie and Nacra crap that all look like poor quality after 10+years and no buffing will fix that

 

Very possibly the gelcoat is ISO-NPG, and the laminating resin behind it is VE. (when using VE, it is very probably that also a high quality gelcoat is used.)

The other boats might be using an ortho or semi-iso gelcoat. Cheap, but not the best option for exterior use.

 

VE construction doesn't mean they used a VE gel coat.



(quote)"Is bad poly still better good VE?"

For the most part if you are looking at gloss and color retention, yes.

 

thanks for the info

 

I concur with Herman's answer. Most gel-coats are neither VE nor ortho-polyester, they are iso-polyesters.

I don't have direct experience, but when I've asked this question I've been told the answer is Duratec - that epoxy boats are pulled from female molds with the outermost layer being Duratec, then polyurethane painted (with only as much fairing and surface prep as the paint pros require). I realize this leaves several questions unanswered, including which of the several Duratec products to use (there is a choice between polyester & vinylester), so I would call Duratec Primers, Hi-Glass & Thinner | Fibre Glast https://www.fibreglast.com/category/Duratec and ask. Also, assuming the mold is fair, you would NOT want a high-build of Duratec; only a thin layer (though note, I've seen a lot of MJMs with print through. I don't know if Boston BoatWorks post-cured the boats.)

Having said all this, I find Doug Lord's alternative answer very interesting - thank you, Doug! I could say more of a speculative nature, but I'd be talking out-of-my ear. One fact that might come into play, though, is that, despite the name, Petit Easypoxy paints are actually polyurethanes.

I'm now wildly enthusiastic about Arkema's Elium thermoplastic resin for both tools (molds) and parts (hulls), so my question becomes whether the surfacing of the mold and all coatings & paints need to be Elium based for the resin to be successfully recovered end-of-life without contamination.