CPES compatibility to 635 epoxy

Placed an order with US Composites and the tech. at US Composites told me “do NOT use CPES on wood and then apply 635 Med epoxy”. I have researched the site and found this has been addressed in the past and have had input from other members say it is an acceptable practice. Just puzzled why US Composites do not recommend this process.

I recently read a very good explanation of what your trying to accomplish and the various systems available to someone laying up a new boat.   Although it was geared more to strength and weight for building go fast boats they had some interesting things about the materials and how they work alone and with each other.   My guess would be from reading that that they are worried about the secondary bond between the CPES coated wood and their laminating epoxy.   Epoxies bond to anything, but they are slick on a molecular level because they so completely react when they cure, not a whole lot left for the next layer to bond to. So the bond between the CPES treated wood and the fiberglass laid over it may not be as strong as it would be if the fiberglass was on untreated wood. Not saying that it is bad, people have done a lot of boats that way around here and I don't think anybody is having issues from it.   

That would be my guess as to why they said that. If you were worked about that then you could get the stringers faired and in the boat so the fiberglass goes after the CPES and everything cures together. That sounds a little difficult timing wise though to me. Another solution would be a good scuffing with some sand paper before you begin laying the fiberglass so there is a better secondary bond.

Tom that is what I did to the side panels I'm building for
my Mustang.I used 1/4" ply and in places I laminated them
together after cpesing them and had used 635 to do it.
I just went out and hit a cutoff piece with a hammer.
here are the pic's,it did not fail at my joint.

before


hit side


back side

I sanded Tom but I have a D/A sander so it was fast.It removed the glossyness of the cpes,I had used about 3-4 coats and I don't think it hurt.Since I was bonding 2 together I had also added some cab-o-sil to the resin mix also.

Thanks Pete. See that last picture,you can also see where the plywood has a gap that I filled with the epoxy and cab-o-sil and amazingly it did not break there either. Now your going to say you could have fitted them better but all that was added later when I realized that stapling into 1/4 might give me trouble,so I had to add a tacking strip all the way around the back side.These things have taken way more time than they should.I traced Johnb's panels but they needed quite a bit of modfication to fit my boat,they were too long and too tall to fit mine,but I'm thankful for the start they gave me.

We use 220 grit and lightly sand to a "uniform flat finnish"
After surface prep compressed air or an acetone swipe and bond.

Bonding should be done within 8 hours of surface prep.

If the surface has a greasy feel it's amine blush,
wash it off with soap and hot water let dry then sand.

I do think in the context of this thread ie cpes to epoxy that this is not a concern.The cpes I used from the rot doctor never felt at all slippery or greasy.

Lots of papers on amine blush out there.
If you heat or cure with gas/oil heat it's an issue
Heat or cure with electricity (heat lamps) not an issue.

It's funny I just layed up 2 Harley bat wing fairings.

(Epoxy and carbon fiber)

The first one cured at 150* under a heat lamp cured perfect
in 1 hour and 15 minutes.

The second after I layed it up and put it under the heat lamps
I pulled my 2 motorcycles into the garage and shut them off.
You could smell the exhaust and monday after work I popped it
out of the mold - And - amine blush.   

just sayin'