Laminate Sample #6: Open Molded Fiberglass / Polyester Resin with Coremat

Laminate Sample #6 in the Explore Composites! Materials Library:
This is an open molded panel with fiberglass skins and a 2mm Coremat core. The face plies are 1oz (9oz / 300g) chopped strand mat and the main reinforcement ply is a single 1708 biaxial glass. "1708" is 17oz biaxial stitched to a 3/4oz chopped strand mat. The resin is Totalboat general purpose polyester laminating resin.
See the rest of the information on this laminate sample at:
explorecomposi...

[@fredygump5578]

Thanks! I bought some of this coremat, but I've never used a product like this....so I figured I should ask KZbin how to do it. This helps me out a lot!

[@ExploreComposites]

I'm glad you found it and that it was helpful!

[@buildonbudgetph4662]

Greetings! Can I use it for crossbow limbs? Thanks!

[@BBBA_]

I love the blue resin.

[@twinstwins9609]

please, add videos with strength tests

[@buildonbudgetph4662]

Greetings! I have a plan to make a fiberglass crossbow limbs. Do you suggest using epoxy resin instead of polyester resin along with coremat and csm? Thanks!

[@ExploreComposites]

I have no experience here but my guess is you want mostly unidirectional fiber/roving with just enough off-axis (braided sleeve over might be good) to keep the thing from exploding. Tougher, higher elongation resin sounds like a good idea - so epoxy or vinylester is probably best. I would avoid any coremat and try to stick to solid laminate. Csm won’t do much structurally but might help buffer the unidirectional material or build thickness without much stiffness. Be careful - this sounds dangerous!

[@prathammistry8401]

what is the thickness of the laminate?

[@tomspettel3646]

I am new to composites and am just learning all this. You say you layup on a teflon sheet? Where can i get teflon sheet? And does it have another name? Thanks tom

[@ExploreComposites]

Hi Tom - here’s a video: kzbin.info/www/bejne/h4e7c6KghdGXr7s There is an article with links to sources on the EC! Site too: explorecomposites.com/articles/tooling/adhesive-teflon-its-awesome/ It isn’t ideal for many things but for one-off, quick tooling and prepregs it is awesome.

[@tomspettel3646]

Ok great theres alot of stuff i visited a friend that is in composites and he uses glass to layup on have you ever used it before

[@ExploreComposites]

Yes, glass is great especially because you can see the back side of your layup. Any mold release will do - wax is fine - but the downside is breaking!

[@tomspettel3646]

@@ExploreComposites Ok great the friend introduced me to a mold release i have never seen before chem trend 41-90 EZ. Have you ever used it No wax and it goes on like rain x. It was amazing !!

[@ExploreComposites]

@@tomspettel3646 Good stuff! Better than wax and way easier to apply.

[@bipedalhominid6815]

Ive always heard 1708 mat side goes down. Whats the difference ?

[@ExploreComposites]

I wanted 1708 with mat on both sides - one to face the surface and one to face the coremat, so I put one mat ply (the 1oz) down and then the 1708, so the "08" mat faces the core. In general secondary bonding stuff like tapes/tabbing, you are totally right the mat should go down first to make a resin-rich bonding surface. You can add mat-only plies as needed too.

[@cesarmuttio506]

Coremat can be laminated with light rovin in boot sides?

[@ExploreComposites]

I'm no expert on coremat, but my understanding is that chopped strand mat should be used on either face of coremat - at least with polyester resin.

[@BBBA_]

...2mm coremat *

[@JC-ve4zm]

A lot of these videos are pretty cool but honesty not that useful. If i want a super strong stiff sheet of something. There are better cheaper options. Showing us how to make composite material structures like this with compound curves would be a wildly better show of each materials strengths and flexibility.

[@ExploreComposites]

You're right about flat panels being boring - I make 'em - I know! The laminate samples (22 and counting) are a way to show a wide variety of material and processing options fast and cheap - the most value for 2-4 hours or so of work. Because they are all the same it gives a uniform framework for comparing them. I hear you on the compound curves thing - all in time. The bulk of my effort has been going toward the explorecomposites.com web site but I am hoping to do more videos in the future. This is still a side / hobby project for me. And I'd love to know about the cheap super strong stiff things you mention. Its my job to know about the cheapest stiffest, strongest ways to build things - so please share. The best part of this for me is all the fun things I learn from other people!

[@daltanionwaves]

JC obviously doesn't have composites or design experience, as the valuable info in these layups has gone completely over his head. Can't believe homie would even entertain a noob comment from a place of ignorance, but it's generous for him to use it as a teaching moment.

[@ukaszwojciechowski4698]

So wrong way of laminating 😱🤯

[@ExploreComposites]

I'm interested in what you'd do differently - you may know good methods I haven't learned yet!

[@whathefukk]

Can I use epoxy resin instead poly resin?

[@ExploreComposites]

Coremat is a polyester non-woven and is compatible with epoxy. You'd want to avoid the chopped strand mat because it has a styrene-soluble binder that will work(ish) with epoxy but not well. You should be able to use a woven/cloth or stitched fabric (like biaxial without mat) sandwiching the Coremat with epoxy. Roll really well and maybe add some fumed silica to the resin to keep it from running out before it cures. I haven't actually done this - just reading the Coremat datasheet and imagining - so do some tests first. Let me know what you find! And thanks - this would be a good test for a future laminate sample.