Select to expand quote

tarquin1 said..
I glued some foam together from left over bits.
Cut it into 3 parts. HD foam on the sides and top of the middle section. I have just tacked the sides back on for now. Shape the board then cut the sides off and wrap the central part in carbon. Glue the sides back on and finish the board.
Not sure this is the best way to attack it but it is how I am doing it.

Interesting what your doing there .
Should put it in a seperate board build thread with lots of pics .

There is a guy in the North of France making kiteboards. He says they are eco boards. Looks like he is using flax bamboo and "eco" epoxy. Will look into it more. But sounds like another "eco" selling point rather than a true eco board.

Select to expand quote

tarquin1 said..
There is a guy in the North of France making kiteboards. He says they are eco boards. Looks like he is using flax bamboo and "eco" epoxy. Will look into it more. But sounds like another "eco" selling point rather than a true eco board.

That's what gets my goit. Eco should be eco , not a sales pitch , which unfortunately it mostly is . If there was a standard to eco , we could then possibly go in the right direction .
The way I would like to perceive eco is , what's better for the planet taking into all production ,delivery and user life aspects , end result . Lots different to brochures .
The bigger the eco brochure bark the smaller the dog .
I know , self amusement gold

there is a standard.
sustainablesurf.org have conducted science based studies and created a minimum standard that is quantifiable and being adopted by the surf industry. unfortunately the message got lost earlier in the thread.

some of the construction being discussed here goes well beyond the ecoboard standard. but again the standard is the minimum required for certification and is aimed at commercial boards. as new materials come online the standards are broadened and improved.

Select to expand quote

tarquin1 said..
There is a guy in the North of France making kiteboards. He says they are eco boards. Looks like he is using flax bamboo and "eco" epoxy. Will look into it more. But sounds like another "eco" selling point rather than a true eco board.

Wooden Stuff have some interesting stuff.

Just found this:

www.dsm.com/dyneema/en_GB/sustainability/bio-based-dyneema-fiber.html

Select to expand quote

Overner said..
Just found this:

www.dsm.com/dyneema/en_GB/sustainability/bio-based-dyneema-fiber.html

i posted this earlier.
tried to track down the fabric but can't find where it's readily available yet.

cycling clothing is being being made from the cloth so it's in the wild but i can't find the cloth for sale.

the race is also on for biobased carbon fiber and biodegradable bio epoxy.

I gave up waiting for change climate bio resin to become available again and bought sicomin greenpoxy 56 so i could get the build back on track. Hopefully get the thread back on track too. The board is an 84lt rocket air for my 12yo son. A fast, turny bump and jump rocket.

I wasnt overly happy with the rail volume after the cnc process so the delay of the resin allowed me time to revist the hand shaping till i was satisfied. Finally got there.















Foam is 100% recycled eps from local company. Sandwich is end grain balsa from nsw surfboard builder.


To get the balsa core flush i taped an outline and routered the deck then hand finished after the router








Next the balsa was cut to fit so its ready to go when needed. The tape is to hold it in position temporarily so i get an accurate edge.

What will the lay up be , Are u going to vac the balsa ?

layup is a mix of biax basalt, uni basalt and rPET cloth plus hoop pine patches.

no vac bagging.

May I suggest using plenty of thickened resin between the balsa and blank .

i've been reading a lot of research papers about fillers and the problem is thickening resins within the structural layer weakens the sandwich considerably.

i get what your suggesting tho
so, i'm planning to seal the balsa with a light layer of resin sponged on and sanded back. i had 2 surfboard makers suggest that method so fingers crossed.

Ever thought of doing the method where you vac bag on a layer of wood using polyurethane glue? Usually its Paulownia and some surfboard builders don't even glass over it.

i was almost going to do it that way for this build. was thinking of gluing planks to the foam. would have been cheaper as i could get the paulownia for free.

I'd be very tempted to try it. Supposedly the surfboards made that way are very durable, I'm guessing you could just do your normal flashing schedule over top.

Careful of a dry join if your going straight onto the blank . Like cork , end grain balsa will suck up heaps of resin . Same as the blank . Maybe a thicker glue will be better . I know this from painful experience

Select to expand quote

Grantmac said..
I'd be very tempted to try it. Supposedly the surfboards made that way are very durable, I'm guessing you could just do your normal flashing schedule over top.

Could also finish with clear 2 pac urethane and leave out the glass cloth.

Select to expand quote

Imax1 said..
Careful of a dry join if your going straight onto the blank . Like cork , end grain balsa will suck up heaps of resin . Same as the blank . Maybe a thicker glue will be better . I know this from painful experience

Ive sealed the blank with a qcel mix. The balsa forms the sandwich core so it sits between layers of cloth and not direct to foam.

Im concerned about resin take up with balsa and i hope sealing the balsa with a thin layer of epoxy helps.

Time will tell. Interestingly im only using sandwich construction because the foam is low density. If i can find a higher density recycled eps next time ill forget the sandwich.

Select to expand quote

Gestalt said..

Grantmac said..
I'd be very tempted to try it. Supposedly the surfboards made that way are very durable, I'm guessing you could just do your normal flashing schedule over top.

Could also finish with clear 2 pac urethane and leave out the glass cloth.

Good enough for a surfboard but I think not a windsurf board. Perhaps for wingfoiling?

I guess it depends. Always wanted to build a windsurfer one design out of planks.

Select to expand quote

Gestalt said..
i've been reading a lot of research papers about fillers and the problem is thickening resins within the structural layer weakens the sandwich considerably.

You sure about that? Can you site the papers, please? I would be interested to read them. As I have been reliably given a very different point of view from other people. For example, I did Jury service with a chap who was a professional boat builder and composite specialist who had built composite parts for the Americas Cup Yachts. They used thickened epoxy frequently as part of the sandwich lay up process to reduce the amount of resin take up of HD Foam surfaces. He even described to me how it should be done to get the best weight to strength! If you think about the surface structure of the PVC foam / balsa you will understand why filling them is important, especially if you want a consistent bond.

I would suggest the structural weakness you are alluding to might be to do with resin starvation, rather than the thickened epoxy itself, which means the bond is weaker.

On the board I'm building now , ( FKDup Mk2 ) , I rolled a thin layer of resin on the board and on the pvc . Then used a thickeded resin in between , wet , all at once . I used the thin resin on both the surfaces so it soaks in a little and to make sure the thickened resin sticks properly . Nothing worse than a dry join , ( newly learned word of the month , resin starvation ) . It does make things heavier but it's a sure thing without using a vac bag . To get pressure on the pvc on the domed deck is easy with heaps of tape pulling down . The method I used for the double concaved bottom was more complex , probably a first and amusing . Board supported on bench . A stiff cardboard wall around the outside of the board . Everything in ready position , checked twice , dry rehearsal , phone off the hook , wife warned because Ive got just 20 min to do all this . Heart beat racing...... Make resin mix . Roll thin layer on board and pvc . Thicken remaining mix with quell to mayo consistency . Apply to board with grooved squeegee . Lay pvc on board . Cover in plastic sheet , cover plastic with thin layer of soft foam sheet . Shovel wheelbarrow load of stones on top to push everything down. Fingers crossed . Worked perfect

Select to expand quote

Overner said..

Gestalt said..
i've been reading a lot of research papers about fillers and the problem is thickening resins within the structural layer weakens the sandwich considerably.

You sure about that? Can you site the papers, please? I would be interested to read them. As I have been reliably given a very different point of view from other people. For example, I did Jury service with a chap who was a professional boat builder and composite specialist who had built composite parts for the Americas Cup Yachts. They used thickened epoxy frequently as part of the sandwich lay up process to reduce the amount of resin take up of HD Foam surfaces. He even described to me how it should be done to get the best weight to strength! If you think about the surface structure of the PVC foam / balsa you will understand why filling them is important, especially if you want a consistent bond.

I would suggest the structural weakness you are alluding to might be to do with resin starvation, rather than the thickened epoxy itself, which means the bond is weaker.

i'm keen to know what you were told.

everything i've found so far points to reduced strength with fillers. makes sense there is less epoxy and less density.

below are some papers i've read. not sure why i can't post links to seabreeze.

Effect of Filler Content on the Performance of Epoxy/PTW Composites (hindawi.com)
Mechanical properties of sandwich composite made of syntactic foam core and GFRP skins (usq.edu.au)
Microsoft Word - 043_Valasek_P (llu.lv)

west systems page also says fillers reduce strength in the section epoxy fillers and epoxy strength.
Epoxy Fillers - modify marine grade WEST SYSTEM Epoxy

Select to expand quote

Imax1 said..
On the board I'm building now , ( FKDup Mk2 ) , I rolled a thin layer of resin on the board and on the pvc . Then used a thickeded resin in between , wet , all at once . I used the thin resin on both the surfaces so it soaks in a little and to make sure the thickened resin sticks properly . Nothing worse than a dry join , ( newly learned word of the month , resin starvation ) . It does make things heavier but it's a sure thing without using a vac bag . To get pressure on the pvc on the domed deck is easy with heaps of tape pulling down . The method I used for the double concaved bottom was more complex , probably a first and amusing . Board supported on bench . A stiff cardboard wall around the outside of the board . Everything in ready position , checked twice , dry rehearsal , phone off the hook , wife warned because Ive got just 20 min to do all this . Heart beat racing...... Make resin mix . Roll thin layer on board and pvc . Thicken remaining mix with quell to mayo consistency . Apply to board with grooved squeegee . Lay pvc on board . Cover in plastic sheet , cover plastic with thin layer of soft foam sheet . Shovel wheelbarrow load of stones on top to push everything down. Fingers crossed . Worked perfect

i decided to only sandwich the deck so i avoid the wheel barrow lol.
that may be the downfall of this board.

This article in Yachting World might be of interest
www.yachtingworld.com/extraordinary-boats/flax-27-cork-decks-electric-propulsion-most-eco-friendly-yacht-127402

Select to expand quote

John340 said..
This article in Yachting World might be of interest
www.yachtingworld.com/extraordinary-boats/flax-27-cork-decks-electric-propulsion-most-eco-friendly-yacht-127402

thx for the link... so so nice.

Select to expand quote

Gestalt said..

Overner said..

Gestalt said..
i've been reading a lot of research papers about fillers and the problem is thickening resins within the structural layer weakens the sandwich considerably.

You sure about that? Can you site the papers, please? I would be interested to read them. As I have been reliably given a very different point of view from other people. For example, I did Jury service with a chap who was a professional boat builder and composite specialist who had built composite parts for the Americas Cup Yachts. They used thickened epoxy frequently as part of the sandwich lay up process to reduce the amount of resin take up of HD Foam surfaces. He even described to me how it should be done to get the best weight to strength! If you think about the surface structure of the PVC foam / balsa you will understand why filling them is important, especially if you want a consistent bond.

I would suggest the structural weakness you are alluding to might be to do with resin starvation, rather than the thickened epoxy itself, which means the bond is weaker.

i'm keen to know what you were told.

everything i've found so far points to reduced strength with fillers. makes sense there is less epoxy and less density.

below are some papers i've read. not sure why i can't post links to seabreeze.

Effect of Filler Content on the Performance of Epoxy/PTW Composites (hindawi.com)
Mechanical properties of sandwich composite made of syntactic foam core and GFRP skins (usq.edu.au)
Microsoft Word - 043_Valasek_P (llu.lv)

west systems page also says fillers reduce strength in the section epoxy fillers and epoxy strength.
Epoxy Fillers - modify marine grade WEST SYSTEM Epoxy

I think I understand where you are coming from, with these texts. And with the tests done you would be right. If you put additives in to neat epoxy it will be weaker. To be honest that is sort of a given i.e. put a filler into epoxy and you are increasing the distance between the crosslinked chains.

But... the net benefit of a filler is to bulk out and reduce the density of the resin. The papers you put forwards were testing the strength of the resin itself.

Using a filler to fill the micropores of a high density foam core surface is quite a different application of the filler to what is described in your sited papers. What I am trying to achieve by filling the micro pores is create an homogenous surface for the rest of my laminate to stick to. A bit like putting spackle on a blank. If you imagine the surface as a honeycomb (or in the case of polystyrene lots of gaps between spheres), you can either let the foam absorb resin to fill the spaces - which is heavy, dense and expensive - or you can prefill these holes with a much lower density thickened epoxy. This makes the surface flatter, giving a good surface for your laminate to stick to.

Next time you have some left over resin laminate the surface of some polystyrene and smear resin into the holes. You will find when it is cured there there are lots of resin nests. These nests are denser, tougher, more brittle than the surrounding material. When you pull your laminate off the polystyrene you will bring the resin nest with you and some of the balls of polystyrene. If you had a failure the crease line will be around the denser resin where the low density material meets the high density resin. So the way to get a more consistent surface is to fill the gaps with a material closer in density and material properties to get that flat homogeneous surface. It will also be cheaper and lighter.

The filling of the PVC surface has been advice from several composite builders, with a view to improve the bond between the laminate and the gap filling sandwich component - i.e. the PVC / Balsa / Cork etc. It is not used in the structural resin layer within the laminate itself. Although if you are after some interesting characteristics, it is possibly to use polyurethane additives to epoxy to allow the epoxy more 'give' before complete failure. I have tried this in composite alaias when I wanted the board to be more bendy. It worked better than I had expected, although the surface was a PITA to finish as my normal hot coat just flaked off in sheets.

Does that help?

Select to expand quote

Overner said..

Gestalt said..

Overner said..

Gestalt said..
i've been reading a lot of research papers about fillers and the problem is thickening resins within the structural layer weakens the sandwich considerably.

You sure about that? Can you site the papers, please? I would be interested to read them. As I have been reliably given a very different point of view from other people. For example, I did Jury service with a chap who was a professional boat builder and composite specialist who had built composite parts for the Americas Cup Yachts. They used thickened epoxy frequently as part of the sandwich lay up process to reduce the amount of resin take up of HD Foam surfaces. He even described to me how it should be done to get the best weight to strength! If you think about the surface structure of the PVC foam / balsa you will understand why filling them is important, especially if you want a consistent bond.

I would suggest the structural weakness you are alluding to might be to do with resin starvation, rather than the thickened epoxy itself, which means the bond is weaker.

i'm keen to know what you were told.

everything i've found so far points to reduced strength with fillers. makes sense there is less epoxy and less density.

below are some papers i've read. not sure why i can't post links to seabreeze.

Effect of Filler Content on the Performance of Epoxy/PTW Composites (hindawi.com)
Mechanical properties of sandwich composite made of syntactic foam core and GFRP skins (usq.edu.au)
Microsoft Word - 043_Valasek_P (llu.lv)

west systems page also says fillers reduce strength in the section epoxy fillers and epoxy strength.
Epoxy Fillers - modify marine grade WEST SYSTEM Epoxy

I think I understand where you are coming from, with these texts. And with the tests done you would be right. If you put additives in to neat epoxy it will be weaker. To be honest that is sort of a given i.e. put a filler into epoxy and you are increasing the distance between the crosslinked chains.

But... the net benefit of a filler is to bulk out and reduce the density of the resin. The papers you put forwards were testing the strength of the resin itself.

Using a filler to fill the micropores of a high density foam core surface is quite a different application of the filler to what is described in your sited papers. What I am trying to achieve by filling the micro pores is create an homogenous surface for the rest of my laminate to stick to. A bit like putting spackle on a blank. If you imagine the surface as a honeycomb (or in the case of polystyrene lots of gaps between spheres), you can either let the foam absorb resin to fill the spaces - which is heavy, dense and expensive - or you can prefill these holes with a much lower density thickened epoxy. This makes the surface flatter, giving a good surface for your laminate to stick to.

Next time you have some left over resin laminate the surface of some polystyrene and smear resin into the holes. You will find when it is cured there there are lots of resin nests. These nests are denser, tougher, more brittle than the surrounding material. When you pull your laminate off the polystyrene you will bring the resin nest with you and some of the balls of polystyrene. If you had a failure the crease line will be around the denser resin where the low density material meets the high density resin. So the way to get a more consistent surface is to fill the gaps with a material closer in density and material properties to get that flat homogeneous surface. It will also be cheaper and lighter.

The filling of the PVC surface has been advice from several composite builders, with a view to improve the bond between the laminate and the gap filling sandwich component - i.e. the PVC / Balsa / Cork etc. It is not used in the structural resin layer within the laminate itself. Although if you are after some interesting characteristics, it is possibly to use polyurethane additives to epoxy to allow the epoxy more 'give' before complete failure. I have tried this in composite alaias when I wanted the board to be more bendy. It worked better than I had expected, although the surface was a PITA to finish as my normal hot coat just flaked off in sheets.

Does that help?

which filler are you referring to?

Select to expand quote

Gestalt said..

which filler are you referring to?

I don't understand the question.