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Re: paulownia wood

Posted: Fri Feb 02, 2018 5:34 am
by downunder
The reason why the industry is not using a spruce is exactly the number of knots. Big knots.

A knot in the wood is harder to break, so the softer wood surrounding it is what gives way under load.

So, yes, there is a problem with a local wood. If Slingshot is doing it, that does not mean they doing it right. They can afford good spruce when buying in bulk. They can finger join.

I can't buy in bulk, and can't join.

Re: paulownia wood

Posted: Fri Feb 02, 2018 7:07 pm
by Greenturtle
Slingshot uses paulownia according to their website. And yes their blanks generally have knots.

Perfectly straight grained, and knot free, Spruce and/or Cedar is readily and widely available in both USA and Canada. And its cheap.
(In the U.S., Lowes and Home Depot carry both of these species for example. And its very easy to pick out perfect boards from the selection at these stores)
If shopping with a real lumber supplier its even easier, and the species selection wider.

Re: paulownia wood

Posted: Fri Feb 02, 2018 9:47 pm
by wood1
there is this older youtube film from slingshot showing their factory ,I guess in 2013 they used what look like local knotty spruce
phpBB [video]

Re: paulownia wood

Posted: Sat Feb 03, 2018 6:36 pm
by rtz
Maybe it’s been done before but I thought it was interesting to see short pieces turned on end to make up a sheet vs’s strips:


http://www.star-board-windsurfing.com/2018/flax-balsa/

Re: paulownia wood

Posted: Wed Feb 07, 2018 11:30 pm
by Grkite
I have to admit various issues with pawlonia. Maybe yes the industry is using ...for sure there is a better way. But that one won't be feasible...
Now I see a lot of advertisement for environmental friendly products that is kind of annoying...the focus on materials that come from sustainable development/forest and the epoxy is so friendly and all the plastic..graphics..and actually the end product is a sandwich or epoxy glassed wood...that no one says how this is gonna be recycled..re used atleast?...
So even the anisotropic/orthotropic of pawlonia sheets, I believe that you gain on the other issues...like shapping, flexibility, lightness,...

Re: paulownia wood

Posted: Thu Feb 08, 2018 7:44 am
by rynhardt
Paulownia is used mainly because it makes boards cheaper to manufacture. It's an acceptable substitute for structural foams.

Re: paulownia wood

Posted: Thu Feb 08, 2018 12:21 pm
by jannik
rtz wrote:
Sat Feb 03, 2018 6:36 pm
Maybe it’s been done before but I thought it was interesting to see short pieces turned on end to make up a sheet vs’s strips:


http://www.star-board-windsurfing.com/2018/flax-balsa/
Yes, that would be interesting. From my experience with paulownia (and other woods) the strength and flex properties comes from long fibers along the bend direction. I'm yet to snap a paulownia surfboard but I have had them split because of lack of glass to hold the fibers together. With a deep concave you get a lot of cross fiber tearing force when jumping. Starboard claim they gain strenght from connecting top and bottom surfaces with fibers....top and bottom of what? The thin piece of wood laminate? I think normally when you want to add strength that way, you would connect the outer surfaces.

But of cause we need to keep in mind what they actually are trying to accomplish which is an alternative to PVC - not to better a regular sheet of wood. I doubt this is a good alternative for wooden surfboards or as the main strength and flex control in a tt.