Laminate Sample #39: Open-Molded Glass Mat / Polyester on Polypropylene Honeycomb Core

[@ninehundreddollarluxuryyac5958]

I made a countertop in my boat with that honeycomb. The top was one layer of 4 oz surfboard cloth so you could see the honeycomb through the glass very clearly. This was followed by a thick coat of clear countertop epoxy. Run a torch over it to pop any bubbles in the epoxy and repeat every half hour or so until it starts to harden. The honeycomb looks so 3-D

[@sarbaba]

What is the Silica thing you mixed? How is it useful? Recommend any brand for that?

[@wagnerjose2345]

What is the viscosity of this polyester resin?

[@ExploreComposites]

Depends on temperature but probably up near 800 or 1000cps at room temperature. The styrene and breaking down reinforcement (mat) binders make it feel much thinner in use than the viscosity in a cup would lead you to expect.

[@eliasmichalis]

Thanks for sharing with us. I plan to make a boat gangway 3 m x 45 cm. I want to make with 20mm plastic honeycomb core. Any ideas how many layers of fiberglass (200 gr. thickness) should I use? The load capacity should be 250 kilos. Any idea well come.

[@ExploreComposites]

I am not going to go pretengineering in KZbin comments but would suggest that 20mm core is probably not enough. At 3m, you will want some type of structural "tubes" along the edges with a deck that need only support the 45cm span, or more serious engineering. Look into yacht "passarelles" made from composites - people build some pretty fancy stuff.

[@mrgboxx]

thanks for sharing. question, (hope its not too dumb) i know you can use polyester resin to lay the fiberglass on top of the honeycomb, but is it okay to use it to join the honeycomb edges? or should that strictly be epoxy resin? for example, if i'm making a box with honeycomb, can i stick everything with thickened polyester resin (peanut butter)?

[@ExploreComposites]

Yes, polyester should be fine - or at least that's what I'd do. I am not actually sure how the resin will stick to the edges of the cells but in practice it should key in there well enough for joints or corners even if the adhesion is sub-optimal. The scrim on top is made to be bonded but I'm not sure what the treatment is. You could certainly test the edge gluing with scrap. With epoxy bonding the joints, I'd worry more about the polyester resin in the fiberglass skins not liking to stick the the epoxy. If you do decide to use epoxy for adhesion, make sure it is well cured and sanded. A methacrylate adhesive like Plexus would probably work well too.