hello all.

i keep reading about the incompatibility of fiberglass mat and epoxy. what is it that makes the mat not work with the epoxy?

i'm a bit concerned as i filled in my transom with west systems epoxy and i used woven roving and mat alternatively to build up the glass layers on the inside and out.

am i looking at having to grind it all away and start anew? it sure does seen to be solid and as hard as a rock.

please advise.

thanks, rob.

just did some google research and i read about the binder in the mat that breaks down with the polyester resin.

i read a technical bulletin from west systems that says the mat will be ok as long as it "wet out" ok. mine seemed to take the resin just fine.

what do you guys think?

thanks, rob.

good ? im thinking you can just leave it as a filler and go over it with 1700 or 1800 material with the epoxy after you grind it..

should be ok,but you could do a small test .

Steve , whats up ?

[QUOTE=vintage chromoly;3561138]hello all.

i keep reading about the incompatibility of fiberglass mat and epoxy. what is it that makes the mat not work with the epoxy?

i'm a bit concerned as i filled in my transom with west systems epoxy and i used woven roving and mat alternatively to build up the glass layers on the inside and out.

am i looking at having to grind it all away and start anew? it sure does seen to be solid and as hard as a rock.

please advise.

maybe I messed up too I just did one with 1708 and 1.5 once mat with us composites epoxy because Steve there recomended it. When I asked about mat and epoxy he told me it would be the way to go. It worked out fine and is as solid as a rock. I needed heavy build up also the outside skin of my 26 profile was only 1/8 inch thick so I ended up with two layers of 3/4 marine ply. and 12 layers of glass total. He told me that the ester resins would not dry or cure well in a transom lay up because the need to air dry and said if I used them to use a glue two part epoxy to bond the transom to the outer skin but the epoxy would be the way to go and I would not need the glue just epoxy.
I keep getting all diferent oppinions on it I hope it will work it looks great and wettedout great and has a super good bond with no voids or air bubbles.

[QUOTE=2manyprojcts;3566895]You should be fine, the 1708 has a binderless mat and if you needed to build it up that laminate will be resin rich. Technically the random orientation of the fiber is a weak link in the stack when used with epoxy, but again you should not see any issues. One of biggest drawbacks when using a bi ax with a stitched mat is how difficult it is to wet out. I would just keep an eye on it.

Dave,

If one were inclined to use epoxy, it seems a low viscosity Epoxy system would be best for 1708?

http://www.adtechplastics.com/pc-64-...ng-system.aspx

What do you think?

Offshore Ginger is gonna blow a nut!

Jeff

The thin stuff is fine and will help but thats not the point. Any mat in any form is unnecessary in an epoxy layup. The proper laminates are readily available and far easier to use. Yes you can use it but there really is no need and its a pain to wet out, plus technically it is a weak link. Try 1700 once and you will never use 1708 again unless using an ester resin. Next time your playing around with resin take two pieces of 1708 and epoxy them down to a scrap piece of rigid fiberglass or something. Apply one with the mat side down and the other with the bi ax side down and let them cure (fully, takes several days) then try and pull them off and see how different the bond is.

Again, not trying to worry anyone that has already used 1708 with epoxy. It is fine in a pinch or if you dont have access to 1700 but there are better ways. Much easier to.

What would be the advantage at all to use 1708 with ester based resins?
Jeff