infused wood panel skins?

General Discussion
1

can someone explain?

Bert was using them in 2004 and Huie confirmed used them in the material thread.

Bert mentioned use of an autoclave which most composite operations use for carbon builds

I’m presuming a highly viscous resin and pressure to saturate the wood without leaving allot in the panel itself

is this done while bagging the raw wood skins on or are the skins “pretreated” as I suspect prior to application.

I belive if you heavily paint one side with some type of thinned and use a perf release/damper on the other in a bag you could infuse your wood 

2

“Aerospace autoclaves normally operate from 120 to 230 degrees Celsius within a nitrogen environment at 7 bars of pressure” (wikipedia)

Hi Bernie - Assuming the use of CNC shaping machines, I suspect that deck and bottom skins could be prefabbed to fit.  At the temperatures described on wiki, wouldn’t light density EPS start to melt?  Another issue is pressure… at higher vacuum levels lightweight EPS is prone to crushing and distortion.  Some very tough composite structures can be built using autoclaves if melting/crushing cores isn’t an issue.

3

John

I’m guessing that, the balsa veneers/boards were “infused” in an autoclave setup prior to usage as an external skin layer.

or…

they are adhered to the core using a fiber laminate and nylon webbing underlayer against  the core with a really viscous glue/resin so that it penetrates through the wood and is absorbed and removed with a peel ply/absorber layer like what charlie showed with his corecork lam. I think you’d want to suck as much excess resin from the pores of the wood so it remains flexible but becomes waterproof and resistant to the deaded wood rot.

Bert mentioned something in one of his posts of just coting the lineing of the tubes within the wood structure that supported  the flow of water in the living wood tissue but not filling the pores up with excess resin that would make it stiff and heavy. I think that’s how Bert, Jarrod and others are able to get such light weight with laminated wood panels as a skin in between two layers of resin staurated fiber.

Paul sugessted another method which was to press in a thickened layer of resin onto the outside surface of the wood panel to seal it and prevent resin saturation but you still end up with a layer of glue that’s stiffer than the wood.

there’s something missing and I know its a trade secret but there’s something missing.

Charlie always overbuilds anyway so his boards last and can survive northshore so weight isn’t a big deal especially since he was placing the wood over standard heavy PU cores in the beginning anyway.

 

but you’re right an autoclave would destroy a light core

but not so if it was just the wood panels placed in there, I think that’s why grain was important to Bert as well

4

Hi

First I want to thank the Sawys community for all the great information that people share, especially to Bert, Lemat, Greg, Oneula and many more…

Recently I finished my first blasa compsand board and I am very satisfied with the result, but like Oneula says, I think there is something missing with the wood pretreatment.

After reading Oneulas last post I remember some search that I made before about wood preteatment.

http://pslc.ws/macrog/mpm/composit/natural/impreg/balsa.htm

Balsa pretreatment with EHMA sems to meet the requirements from Bert comments:

Bert mentioned something in one of his posts of just coting the lineing of the tubes within the wood structure that supported  the flow of water in the living wood tissue but not filling the pores up with excess resin that would make it stiff and heavy. I think that’s how Bert, Jarrod and others are able to get such light weight with laminated wood panels as a skin in between two layers of resin staurated fiber.

What I dont know is how this treatment is applied and what is the cost of it.

Cheers from Spain

5

there’s some stuff you can buy but not like this

don’t know if it makes things heavier although I presume so.

It was tested against 10% diluted resin.

this stuff looks interesting but its mostly water don’t think you can laminate over it

ProteShield - Elastomeric Waterproof Sealer

http://store.getnewlook.com/p/1-gal-proteshield-elastomeric-waterproof-sealer/protect-maintain-sealers_top-coat-sealers?pp=36

MSDS

http://mediacdn.shopatron.com/media/mfg/13020/spec_file/21620610

 

6

Howzit Oneula,

I get what you’re saying and have wondered about that, too.  It would be interesting to know if it’s possible to draw a really thin infusion epoxy through the hollow tube/fibers of balsa or bamboo.  I think you’d need a resin with a UV fluorescing tracer in it and cross-sectional analysis under a microscope to really know if you got the resin inside the wood.

Regarding the material you linked, I’d be hesitant to use that.  Definitely would require some serious adhesion testing, as the solids in it are all siloxanes.  However, it might just work as a foaming agent in the right epoxy (not RR epoxy).

7

infusion as a pretreatment adds unwanted stiffness to a wooden skin…best used in -situ…with balsa , it detracts from the lite weight advantage , and makes it harder for the wood to conform to the boards contours under vacuum .

8

from everysurfer’s material thread posted by Huie 2 years ago:

lemat

        while lab tests may prove you right.  the surf test tell me it holds the lamiate together’’ and resin fracture is not as bad as just using e glass.  

remember  we are talking about  skins  to suit special core and no matter what fibre you  use?   there is non better than wood?

and infused wood with nylon well it just gets better eh’’

try a peel test with the sports net sticks like shit to a blanket 

never used it hand lam?      only vac  and i use a more flexible epoxy than the surf ones

 

i said it over and over  infused wood with nylon is my journy .

so not realy bothered with much else

but hey that dont mean its the only way     just suits me thats all

cheers huie

and a couple quotes from Bert back in 2004:

well that is starting to explain things then…coz i did claim they were more crispy and had a harder feel , 

also ive been working lately with adding toluene and a few other things to my epoxy…the more solvents in there the more flex and rubbery feel you get …so cooking normal epoxy resin surely would release some amounts of solvent or whatever else is in it to make it more flexy… 

thus giving a harder crispier lighter board… 

yea tom what i meant by a closed system , 

the job was set up with no facilities for bleeding off excess resin,the resin that was put on the board wet couldnt go anywhere ,except for vapour out the vacumn pump… 

as far as the comment about temperature yea we were pushing 85 degrees celsius , hotter than that and things would melt … 

but if your vacumning and baking p/u yea 65 is the limit coz you hit the foams hdt…ive made enough dried prunes to have worked that one out… 

where as the hdt on eps is closer to 100 celsius… 

regards 

BERT 

hey joe…ive never used high density eps on rails … 

i have used xps,high density poly-urethane,pvc,and timber combined with low density poly-urethane,ive also used plywood , an aircraft ply that comes in 1/16th thickness,plus different veneers to many to mention… 

any toy store should have balsa, 

thats all i use… 

of coarse ive chased it right back to the source now…so i can pick density and colour , plus get whatever thicknesses and widths i want… 

i dont want to be the instigator of everyone rushing out and buying balsa … 

theres a few construction aspects that arent apparent… 

in that the balsa has to be treated a special way so you get good resin penetration and an unbreakable bond between glass resin and wood …that aspect is the key to the strength of these boards… 

not doing that will result in mixed results , depending on your balsa quality…you could end up with a disaster… 

dont stop thinking… 

regards 

BERT "

sorry I have  memory like an elephant for things that continue to bother me like this.

part of being a mad scientist I guess… Always trying to tie remote comments togethor

 

9

If you saturate light wood with resin it became heavy, really heavy. If you want to do that, use ultra low viscosity marin epoxy resin made for it. An other way is to make resin pénétrate with vaccum, resin in one face vaccum in other, had this in à pressurize place help (autoclave). An other help is température gradiant that increase capillarity of wood.

10

If you treat the wood it allways will gain more weight.

The key is to improve the specific properties of the wood, specific toughness and water absortion while maintaining the flex properties.

To maintain the flex properties the treatment material need to bond to the wood cell wall structure and not to fill the holes or cell lumens.

After reading some papers on the web they say that the treatment material must have a chemical structure compatible with that of the cell wall material such that the majority of material is incorporated into the cell wall.

http://www.researchgate.net/publication/229531634_New_lightweight_materials_Balsa_woodpolymer_composites_based_on_ethyl_(hydroxymethyl)acrylate

Cheers

 

11

AMS,

That’s some good stuff that you linked.  Thank you for sharing. 

12

A pleasure, I learned a lot of things from the community so somehow feel I need to start contributing.

My first balsa compsand came out pretty well, I used 2mm planks bottom and 2.5mm planks in deck. I have not treated the balsa before the final lamination and I placed 4 oz E glass above and below the wood, the fiber bellow wood was glassed by vacuum bag making a prefab skin, the glass above was glassed by hand like a normal surfboard. After laminating I applied a very thin hot coat and an automotive 2 pac finish.

The board rides great but In the deck (2.5mm plank) if you press hard with the finger you can leave a small dent with the form of your thumb, I think is the balsa core that is compressing, dents seems to only occur with localized force because no foot dents happen after riding the board several times . The balsa that I used was of 140 kg/m3 density. The bottom that is 2mm seems not to dent and flex with the 12kg/m3 EPS core.

When hand laminating the board I used more resin than expected, so I suppose the balsa has absorved the resin, but seeing the results I think it does not penetrate very much into the plank.

For my next build I plan to thin 50 or 70 gr of epoxy with denatured alcohol and apply it to the wood before placing the fibers and laminate, hoping that it penetrates more into the wood. Dont know if this will affect very much to the flex, dont worried with the weight gain, the last board ended up in 2kg.

Cheers from Spain

PD: I want to especially thank to Bert for sharing a part of her hardly owned knowledge and experience.

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