Chopped stand matt & epoxy

[mars bar]

Bought the west epoxy and resin (slow), chopped strand matt & roving, and hi ho hi ho off to work i go, i even read the west systems manual "and thats good for me". Doing a large area internal & extenal on my cabin & 1/3 all done and looking good.Then a wise man noted i was using epoxy, foaming @ the mouth he said "you CAN'T use epoxy with chopped matt binders wont disolve with epoxy. Well thats not in the manual,so now what, is all my work going to fall apart ? Any NASA engineers out there

[mars bar]

Originally Posted by mars bar

Bought the west epoxy and resin (slow), chopped strand matt & roving, and hi ho hi ho off to work i go, i even read the west systems manual "and thats good for me". Doing a large area internal & extenal on my cabin & 1/3 all done and looking good.Then a wise man noted i was using epoxy, foaming @ the mouth he said "you CAN'T use epoxy with chopped matt binders wont disolve with epoxy. Well thats not in the manual,so now what, is all my work going to fall apart ? Any NASA engineers out there

With every wish there comes a curse

[roverhi]

Depends on the type of mat. Some mat has a binder that is soluble by polyester resin but not Epoxy. There is matt available that has binders that dissolve in Epoxy, however. Any resin/matt dealer worth their salt should have told you if the matt was not epoxy compatible.

Probably best indication of type of epoxy compatibility is how the job has gone so far. Has the matt wetted out and conformed to the shape that you are laminating to?? If so, you are probably safe.

Aloha
Peter O.

[mars bar]

Hi Peter. Well the job looks good and sounds solid when i tap on it,and yes, tomorrow i'm off to have a chat with that dealer. Thanks

[Alan Wheeler]

I think you will be OK if the matt wetted out. But still talk to the dealer to make sure. But even if the matt is wrong, I still think you are OK. I assume this is a sheathing situation, not a high stress loading situation?? If it is sheating, then you probably didn't need to use Chopped strand anyway. That will use up a lot of Resin. Glass cloth is all that is really needed to sheath. Chopped strand is used for high build area's and the fact that ester resins are not that strong.
One thing you do really need to watch when using Epoxy and chopped strand, is that you don't build up to thick a layer that will cause the mix to over heat. It can do so and can be disasterouse.

[cat man do]

Whats chopped strand mat and rovings??

Dave

[Alan Wheeler]

Chopped strand mat is a mat of glass that has short strands of that glass all mixed together in compleate kaos and pressed into a flat mat cloth. It is quite thick, hence the term mat. It also falls apart easily as the only thing that binds the strands is usually a coating applied to the strands. It is designed mainly for Ester resins and the coating is usually a product that disolves easily in easter to enable a good wet out of the the thick mat.
A roving is a more like a cloth. Long glass strand have been woven uniformaly to form the cloth. Different weaves will create different cloths for different purposes of use. Depending upon what directions load is wanting to be applied along the cloth. You can have very thin sheathing cloth through to heavy cloths. Cloth that is bi-directional and even tri-directional. Cloth with non-glass fibres woven in in, like Carbon and Kevlar, or it maybe all Carbon or Kevlar and so on. The list goes on.

[GordMay]

Chopped Strand Mat is a random fiber reinforcement, composed of chopped fiberglass of various lengths, randomly dispersed to provide equal distribution in all directions. Chopped Strand is designed for use with polyester and vinyl ester resin systems. Because it uses a styrene monomer soluble binder, to hold strands in place, it’s not compatible with epoxy resin systems. Chopped strand mat is commonly used in laminates to minimize weave print through, due to ease of wet out, the good bond provided between layers of woven roving or cloth, and is comparatively low in cost.

Woven Roving is continuous strands of glass fiber, grouped together to form a twisted yarn. The roving is then woven into a coarse, square, lattice-type open weave to form the material. Woven roving provides great tensile, flexural, & impact strengths, at moderate cost. It’s more difficult to wet out than chopped strand mat or cloth however, and because of the coarse weave, it is not used where surface appearance is important. A layer of chopped strand mat is used between each layer of roving, to fill the coarse weave, when more than one layer is required. Compatible with most resin systems.

[Whimsical]

Wheels and Gord
He's yanking your chain. Outdated technology for cats.
Mike

[cat man do]

But nice explanations anyway. :-)

Dave

[mars bar]

Thanks Wheels and Gord but whats Dave all about, i get the impression the hes not a glass fan,nice craft tho what ever its made of. So I'm just going to go over the work I've done with cloth,and thanks anyway Dave. As for the Dealer, he's given me a gallon of resin [epoxy] for my troubles, his mistake he said.

[cat man do]

Originally Posted by mars bar

Thanks Wheels and Gord but whats Dave all about, i get the impression the hes not a glass fan,nice craft tho what ever its made of. So I'm just going to go over the work I've done with cloth,and thanks anyway Dave. As for the Dealer, he's given me a gallon of resin [epoxy] for my troubles, his mistake he said.

No mate, I'm fine with glass, just that in OZ, not many will use choppies and rovings as it is outdated technologie, especialy in a lightweight composite structure.

I havent seen any for at least 15 years now.

We all use stitched fabrics and epoxy, using a thick core.

EG: my cat (50ft) has a 16mm light timber core (Kiri) and 600gsm Double Bias either side, with additional layers in strategic areas.

Whimsicals Schionning would be similar on a Balsa core.

We can get a Lighter, stiffer, stronger panel by using better(more expensive) materials, but I must add that we would also use much less of those materials (epoxy) to wet out the glass.

Woven Rovings and Choppies will be much more resin hungry than the equivelent strength stitched fabric and then Kevlar would use even less resin again for the equivelent strength.

There is nothing new or space age about this technology, it has been around for 20 years or more, maybe your resin supplier had an interest in selling you more epoxy.

Dave

[chinaweibo]

Chopped strand mat is a non-woven reinforced material. It is manufactured by spreading continuous filament roving of 50mm in length, distributed it at random uniformly held together with powder or emulsion binder.

[GordMay]

Greetings and welcome aboard the CF, chinaweibo.

[Lepke]

I've been using epoxy and RSM for as long as I can remember. Mostly for decks and fishholds. I redid the decks on this boat with 2.0 RSM and West. The prior poly resin and cloth deck was loose in many areas. Generally on non-commercial boats an epoxy/rsm deck will last almost forever with proper care. I've seen decks on commercial boats go 20 years with care. No wet out issues, strands will dissolve. Use a good fiberglass roller. I make 90° bends where the deck meets the cabin w/o problems. Epoxy makes a much better bond between layers than poly.