Orca 17 - Thickened Epoxy

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spelleti2021
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Orca 17 - Thickened Epoxy

Post by spelleti2021 »

I am building an Orca 17 and purchased the epoxy kit. It came with some Silica and some Wood Flour. I need to join some panels and the instructions call for using thickened epoxy. Does anyone know if the epoxy is thickened with Silica or Wood Flour or a combination?

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Re: Orca 17 - Thickened Epoxy

Post by fallguy1000 »

I always thought they were interchangeable, but if any show, wood flour may be nicer on wood.
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BarraMan
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Re: Orca 17 - Thickened Epoxy

Post by BarraMan »

spelleti2021 wrote: Sat Sep 04, 2021 7:40 pm I am building an Orca 17 and purchased the epoxy kit. It came with some Silica and some Wood Flour. I need to join some panels and the instructions call for using thickened epoxy. Does anyone know if the epoxy is thickened with Silica or Wood Flour or a combination?
I used wood flour for 95% of my build. The only occasions that I added silica to the epoxy/wood flour mix was for vertical fillets - to prevent sagging!

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cape man
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Re: Orca 17 - Thickened Epoxy

Post by cape man »

The wood flour is for gluing and the silica is for filling and fairing.
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Re: Orca 17 - Thickened Epoxy

Post by fallguy1000 »

cape man wrote: Sun Sep 05, 2021 6:18 am The wood flour is for gluing and the silica is for filling and fairing.
Do not use silica for final fairing my friend. It gobbles sandpaper. Prefairing before glass is okay...just to be clear. It is so hard; when you use it for prefairing, the plywoods or foams usually sand down dimensionally before you get it flat, so use care to apply it flat.

Lee or Barraman explains it best as I have not used much wood flour and only silica and balloons. But you need silica to stop fillets from sagging per him. Generally, I try to immediately tape over fillets to avoid sanding, sagging, and to gain primary bonding vs secondary.
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cape man
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Re: Orca 17 - Thickened Epoxy

Post by cape man »

I assume that what he has is the blended filler sold with most epoxy kits here, not pure silica. It is a mix of phenolic microbaloons and silica, and purple in color. It is much harder to sand than Quick Fair, but is designed for filling weave, making your own fairing compound, and preventing sagging. I have used both and switched to spending the extra $ and use quick fair exclusively now for fairing because it sands much easier.
It is not as structural as wood flour, so not recommended for thickening epoxy for glue.
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Re: Orca 17 - Thickened Epoxy

Post by TomW1 »

cape man is correct the kit contains wood fibers and blended filler, no silica. I looked it up.

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Re: Orca 17 - Thickened Epoxy

Post by spelleti2021 »

It is purple blend as Cape Man suggested . Many thanks to all who provided advice

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