shark - To get enough nose rocker (not much, it is only a 5' kiteboard) I glued an extra layer, overlapping the under layer, up front. I did sand the slick skin off first. Used Gorilla Glue (PU). The board has been shaped for days and the glue line looks like it might be strong, though it is brownish color, so I probably would use epoxy for glue next time. The board is already Woodpecked. I will glass one side tomorrow as the temperature is going down. Nice looking, your boards.
sanded - Right now my board looks as rough as what you posted, just pink.
Go for it John. I hope you enjoy it as much as I do my boards.
Not very clued in to kite boards, but I think you may want to glass it heavier than a standard board. Maybe you can let the lam cure in a hot area before doing the next side to get as strong as possible.
shark - Lots of kiters jump big and land hard, but not me. I am glassing light to see if, when and where delamination or breakage happens under my use. It is a minimalist thing. No worries ... I have proven strong factory boards for backup.
surfding - I have read that hotwires are easy to rig and efficient. However, just a saw, disc grinder and sandpaper worked really easily. Since I live in Colorado and get to the coast only a month a year, I will probably only do a board shape or two a year.
Greg - What "Skins" and foam are we talking about?
GregTate is talking about the nylon fabric product called "Skinz." Graphite Masters in CA supplies it. Reportedly improves bonding and strength.
Yeah I PMed Everysurfer a while back and told him I was thinking about using Skinz between two sheets of XPS. He tried it on the tail of one of his boards that he wanted to add another layer of foam to, to stiffen/thicken (EPS I believe) the tail. And he felt the bonding was much better.
I suspect the Skinz finer nylon fabric combined with its properties are how it helps. (See Everysurfer's Cerex thread over in Errors & Bugs). A finer fiber pattern with greater strength should have greater surface contact with the foam below. You still need all the increased foam surface area created from the fine/small valleys and peaks made by the 40 grit sanding (creating a surface more like the porous surfaces of EPS and PU).
Cerex thread (you must wade through some flaming and lots of static in that thread):
I plan to use Skinz under some carbon fiber lams and maybe between a thin sheet of EPS bonded to the top of a 2-sheet/layer XPS blank. May try it between 2 sheets of XPS (haven't decided yet whether I think that would really improve the blank.)
Wow, Bg - Your interest in building the toughest light board may be way beyond my interest in building a simple, cheap, light board that lasts a month of daily use. I only read the first 6p and the last 4p of the Cerex/Skinz link. I can see how others might be interested before their next build.
The glass-foam bond I am getting is already strong enough to pull up a layer of foam. On perforated vs just 60 grit sanded foam the bond seems a little better but that is only because more foam is involved - a little deeper layer of foam is pulled up. The problem is the foam is not very strongly adhered to itself.
I know that a tougher glass or whatever envelope around the foam would protect it more from stress leading to delamination, but I think I would only be interested if the schedule were already accepted as cheaper/easier than glass layers. That is just me.
Skinz is a very light and thin cloth, that apparently holds a fair amount of resin. I believe the Skinz is just a much lighter schedule of the Cerex that ES discusses.
I'm interested in strength for one project but want to ensure better bonding of carbon to the foam surface (EPS and XPS) I will be laminating it too.
I suspect the lower density XPS foam pulls apart (sheers) much easier than higher density XPS, just like it crushes easier.
Another way is to use one of the carpet tools that lavarat has recommended in the past.. Maybe not as cheap as coarse sandpaper but arguably allows a better bond. Just roll it all over the shaped blank and glass. Can be reused indefinitely.
My ears were burning! I never tried the Cerex N-Fusion on XTR foam. I did try it on EPS, and it worked fine. From what was explained to me, it is an intermediary layer between the elastic foam, and the inelastic glass. It provides a layer that is less elastic than fiberglass, but more elastic than foam, so as the foam deforms during flex (the outside of the curve stretches, while the inside of the curve compresses, it allows the fiberglass skin to stay attached through the cycle.
If you buy a roll direct from cerex, it is less than a dollar a yard, and come in different weights. Different colors too! Want a white board? Titanium white.
Mike Daniel dropped a hint that I picked up on. He said that Coil doesn't use fiberglass at all. So I did some searching, and found a nylon 6,6 woven cloth. It is supponsed to be manufactured as a peel ply, but I got some untreated. Bad part is that I've been crushed at work, so I haven't gotten into my shop in ages.
Now here is something I put up on either the "Cerex" thread, or another one I did "Modern Laminates, Cerex and Others" It picked up where Cerex left off. You guys know what Cordura is? It is a woven Nylon 6,6. Common uses are everything from sleeping bags to bullet proof vests, depending on the weave and weight. Problem is that it comes with a urethane coating on it that makes it waterproof. That means it won't epoxy saturate. But it could be used if wetted on both sides, or between two wetted layers. I've just been too swamped to get to try it.
The Cerex thread got hit with the disapearing photos bug. Every photo I've ever downloaded to Sways is gone, So if the thread leaves you confused, drop me a p.m.. Either that, or if we all call Mike Palar, maybe he could put them up again.
My experience on on glueing/repairing an XPS board:
1. I glued a block one end so I could get nose rocker. I could not cut or sand a smooth transition at the glue line - the insulation XPS (a Foamula ugly brown one) tore at the join before it was thin enough to give a smooth finish. I used a liquid glue. Epoxy may have worked out better.
2. I repaired an ugly gouge with expanding PU foam. The board has delaminated here (or maybe the PU foam has let go of the XPS?)
Struggling to get decent EPS in these southern climes, so my next few will probably be from 100mm (~4") XPS block. I love the idea of not worrying overly about water intrusion.
Plastic fiber like polyester or nylon have higher elongation and lower rigidity than fiberglass. At same weight, a laminate of those fibers, with right resin (high elongation), is stretchy but floppy. It will need lower forces to break but more energy (work of force = force x distance) to break than fiberglass. Bonded on a substrat it'll be harder to peel off.
Delamination resulting from shear stress in foam at bond, shear stress increase drastically because of local buckling of skin. So a skin stronger against buckling (stiffer) is an effective way to go against delam.
The board is done except for screwing on fins and padded foot straps. It is a shape and size borrowed from an Ocean Rodeo Mako kiteboard that I once tried and liked in the surf. It is narrow with huge concave.
Foam - Corning pink Formular 250 = psi 25, density pcf 1.55. $20 from hardware store.
Surface prep - 60 grit sanding followed by perforating with Woodpecker.
Resin - Resin Research 2000.
Schedule - One layer Texalium (gift from friend) on bottom; thick, strong, too stiff to drape around rails; pain in a.. Would not use it again. Two layers of 4oz fibergalss on top.
Verdict - $100. But will it dent and delaminate?
Future - If I like it except that it dents/delaminates too easily, I might try getting the hardware store to order a denser Formular, or I might get some foam that surfding recommends. I would try the aggressive perforating wheel that johnmellor posted. I would try Skinz under more glass to make a shell thick and tough enough to not dent or flex ... thus protecting the XPS from crushing ... thus eliminating what is apparently a chief cause of outgassing leading to delamination.
I like this board. I def think increasing the bond/strenght of the deck is the way to go and probably the only concern (aside from not leaving it in the sun). That's why I use it only as a bottomlayer, holds up fine not 1 dent or delam. I sanded it at 40.
Looks cool John. Interested in seeing the fin setup.
Texallium is really stiff, we use a vac bag to get it around the rails. You might have been able to use a spray glue to hold it down before wetting it out. Haven't tried that, but I have heard about people doing it that way with carbon cloth.
shark - This not being a build thread, I hope others do not mind this off topic. The Mako twin tip that my build is based on had just a fin about the size you see, positioned at both ends on the midline. I aim to ride my board one direction only, with my feet rearwardly positioned like on a surfboard, so the only fins are the ones you see. If this board was shaped like a surfboard then the finnage would be too little. Maybe it is too little anyway despite my board's huge concave and soft rails everywhere. It is an experiment for riding in shallows. The fins are screw in, so I can take one or both off, or get or make somewhat larger ones, or make more holes for more fins, or glass big fins on.
Really I posted here to compare glassing techniques on XPS, and showed my board only so commentators could see that I actually did something. I would be happy to talk more other board stuff with you, but probably we should do it by PM.
I saw the blocks in the hsot with the board, so I was wondering if that's how you were going to place the fins. This is all foreign to me since I don't kite or sail board. Looks like you did a good job shaping the board too.
Keep the board out of the sun. That will definitely cause it to bubble up.
Sorry, I use a 2cm XPS bottom in a hollow wooden construction.
I don't think anyone else does this build method, but I think it's a good use for XPS. It makes a lighter surfboard and easier shaping of the bottom and placing of the finboxes.
This last summer after trolling the internet for way too long, I finally went for it and made a surfboard. And then a SUP. And now I want to try again. I decided to go the XPS route partly because it is cheap and partly because of the total DIY aspect of it. I wasn't sure what to do about the delamination factor other than just go for it and see what happens. One day I was telling my father in law about my project and he mentioned this paint he uses as a tile setter, ECO Prime. He said the paint sticks to everything and everything sticks to it. I tested the stuff out on a model and then tried it on the real one.
The Bad: Painting the board adds weight. The texture of the paint makes you use more resin (I think) remember I am new at this. It is a funky grey color.
The Good: The paint definitely sticks to the foam. So far I haven't noticed any delams either during glassing or after some use.
Just thought I would share an outside the box approach. I know it is kind of an odd one. I may post one of the builds as a new thread but didn't think this was the place for it.
No idea why the pictures are sideways! I don't know how to rotate them. Is it a glitch with the new site? If anyone wants to clue me in I would love it, Please. I tried over and over and finally the first one came out the right direction(I don't know why) but the second one never would.
Sanding the seal coat with all those little bumps is going to be a lot of work. Gotta be careful sanding XPS, it will heat up very fast then expand, and you'll burn through whatever you're sanding. I used a slurry of epoxy resin and micro balloons as a seal coat on my last board. I won't add the microballoons again. I had to sand down my board, but I didn't have quite as much texture. You want it smooth before you laminate it, or you'll be sanding through the glass, or you'll have an extra heavy board with that extra resin.
I have only made 2 XPS boards (can't get EPS cheap enough), but both are sound, no delamination or blowing. I use them in the UK, so cold water, no hot days to worry about, although I took one to Barbados in the summer, still no problem, just kept it out of sunlight and never in a hot car. I read a lot of posts and prepared my boards to avoid the problem as best I could. On my last board, after tests which proved an increase in bonding, I used 4 razor blades arranged in parallel, 5mm apart and showing only a couple of mm to create tiny channels for resin to squeegee into. I primed the board with resin before laminating to fill the channels well, minimal resin used. In tests chunks of foam, as opposed to the top layer of foam, came away in a shearing situation, definitly stronger than just 40 grit. Best results were horizontal to shear direction, but this is across the board, as I was worried that horizontal cuts, although really tiny, could promote buckling, I arranged the scoring diagonally both ways, + & - 45 degrees. First board was with resin research Kwik Kick and the second RR 2000, I prefer 2000. Both boards with s glass 2 x 4oz bottom, 2 x 4oz top + 3/4 deck patch, 2" laps throughout. 2nd board was lightest, although slightly smaller, 5'6 x 19 x 2.5 @ 2.8kg without fins, think I'm getting better at using less resin.
Stoneburner, Yes, the paint is a bit thick. I wish I would have weighed the board before and after so I knew how much weight is being added. Next time. Also the paint may round out any fine angles you wanted in the shaped board.
I just used the pink Home Depot foam, the 150 sheets for a surfboard and the 250 for the sup. I know someone on Swaylocks broke down how that all equates to density and compression strength but I don't remember who it was.
I didn't sand the primer paint after I applied it. The final grit would be like 45 grit sandpaper.
http://www.swaylocks.com/files/sanded photos 031.jpg
sanded photos 031.jpg
www.sanded.com.au
shark - To get enough nose rocker (not much, it is only a 5' kiteboard) I glued an extra layer, overlapping the under layer, up front. I did sand the slick skin off first. Used Gorilla Glue (PU). The board has been shaped for days and the glue line looks like it might be strong, though it is brownish color, so I probably would use epoxy for glue next time. The board is already Woodpecked. I will glass one side tomorrow as the temperature is going down. Nice looking, your boards.
sanded - Right now my board looks as rough as what you posted, just pink.
Go for it John. I hope you enjoy it as much as I do my boards.
Not very clued in to kite boards, but I think you may want to glass it heavier than a standard board. Maybe you can let the lam cure in a hot area before doing the next side to get as strong as possible.
Every surfer reported that using the Skins between foam and glass gave
much better adhesion. Should help reduce delam here. If so, that could be a big benefit to this build type.
Someone please try it and report back.
Personally I'm always ready to learn, although I do not always like being taught. - Winston Churchill
shark - Lots of kiters jump big and land hard, but not me. I am glassing light to see if, when and where delamination or breakage happens under my use. It is a minimalist thing. No worries ... I have proven strong factory boards for backup.
surfding - I have read that hotwires are easy to rig and efficient. However, just a saw, disc grinder and sandpaper worked really easily. Since I live in Colorado and get to the coast only a month a year, I will probably only do a board shape or two a year.
Greg - What "Skins" and foam are we talking about?
GregTate is talking about the nylon fabric product called "Skinz." Graphite Masters in CA supplies it. Reportedly improves bonding and strength.
Yeah I PMed Everysurfer a while back and told him I was thinking about using Skinz between two sheets of XPS. He tried it on the tail of one of his boards that he wanted to add another layer of foam to, to stiffen/thicken (EPS I believe) the tail. And he felt the bonding was much better.
I suspect the Skinz finer nylon fabric combined with its properties are how it helps. (See Everysurfer's Cerex thread over in Errors & Bugs). A finer fiber pattern with greater strength should have greater surface contact with the foam below. You still need all the increased foam surface area created from the fine/small valleys and peaks made by the 40 grit sanding (creating a surface more like the porous surfaces of EPS and PU).
Cerex thread (you must wade through some flaming and lots of static in that thread):
http://www.swaylocks.com/forums/cerex-nylon-66-n-fusion-surfacing-veils-...
I plan to use Skinz under some carbon fiber lams and maybe between a thin sheet of EPS bonded to the top of a 2-sheet/layer XPS blank. May try it between 2 sheets of XPS (haven't decided yet whether I think that would really improve the blank.)
http://www.swaylocks.com/forums/2-sheet-xps-blanks
1.10/yard from walmart
nylon lining mesh
all kinds of different colors
all kinds of different mesh sizes
no kevlar and no carbon tow
but again
$1.10/yard
bought 10 yards to play with under my skins and to wrap the rails
"ain't no big ting brudda"
Wow, Bg - Your interest in building the toughest light board may be way beyond my interest in building a simple, cheap, light board that lasts a month of daily use. I only read the first 6p and the last 4p of the Cerex/Skinz link. I can see how others might be interested before their next build.
The glass-foam bond I am getting is already strong enough to pull up a layer of foam. On perforated vs just 60 grit sanded foam the bond seems a little better but that is only because more foam is involved - a little deeper layer of foam is pulled up. The problem is the foam is not very strongly adhered to itself.
I know that a tougher glass or whatever envelope around the foam would protect it more from stress leading to delamination, but I think I would only be interested if the schedule were already accepted as cheaper/easier than glass layers. That is just me.
Thanks, anyway.
Skinz is a very light and thin cloth, that apparently holds a fair amount of resin. I believe the Skinz is just a much lighter schedule of the Cerex that ES discusses.
I'm interested in strength for one project but want to ensure better bonding of carbon to the foam surface (EPS and XPS) I will be laminating it too.
I suspect the lower density XPS foam pulls apart (sheers) much easier than higher density XPS, just like it crushes easier.
around 2005 paul(silly) showed us his "tophat" solution to strengthening the bond between skin and core.
goes something like this:
"ain't no big ting brudda"
Another way is to use one of the carpet tools that lavarat has recommended in the past.. Maybe not as cheap as coarse sandpaper but arguably allows a better bond. Just roll it all over the shaped blank and glass. Can be reused indefinitely.
IMG_0507_0.JPG
John:
Great Ideal!
Kind regards,
surfding
Hi Guys,
My ears were burning! I never tried the Cerex N-Fusion on XTR foam. I did try it on EPS, and it worked fine. From what was explained to me, it is an intermediary layer between the elastic foam, and the inelastic glass. It provides a layer that is less elastic than fiberglass, but more elastic than foam, so as the foam deforms during flex (the outside of the curve stretches, while the inside of the curve compresses, it allows the fiberglass skin to stay attached through the cycle.
If you buy a roll direct from cerex, it is less than a dollar a yard, and come in different weights. Different colors too! Want a white board? Titanium white.
Mike Daniel dropped a hint that I picked up on. He said that Coil doesn't use fiberglass at all. So I did some searching, and found a nylon 6,6 woven cloth. It is supponsed to be manufactured as a peel ply, but I got some untreated. Bad part is that I've been crushed at work, so I haven't gotten into my shop in ages.
Now here is something I put up on either the "Cerex" thread, or another one I did "Modern Laminates, Cerex and Others" It picked up where Cerex left off. You guys know what Cordura is? It is a woven Nylon 6,6. Common uses are everything from sleeping bags to bullet proof vests, depending on the weave and weight. Problem is that it comes with a urethane coating on it that makes it waterproof. That means it won't epoxy saturate. But it could be used if wetted on both sides, or between two wetted layers. I've just been too swamped to get to try it.
The Cerex thread got hit with the disapearing photos bug. Every photo I've ever downloaded to Sways is gone, So if the thread leaves you confused, drop me a p.m.. Either that, or if we all call Mike Palar, maybe he could put them up again.
My experience on on glueing/repairing an XPS board:
1. I glued a block one end so I could get nose rocker. I could not cut or sand a smooth transition at the glue line - the insulation XPS (a Foamula ugly brown one) tore at the join before it was thin enough to give a smooth finish. I used a liquid glue. Epoxy may have worked out better.
2. I repaired an ugly gouge with expanding PU foam. The board has delaminated here (or maybe the PU foam has let go of the XPS?)
Struggling to get decent EPS in these southern climes, so my next few will probably be from 100mm (~4") XPS block. I love the idea of not worrying overly about water intrusion.
Mark,
Following with interest
Plastic fiber like polyester or nylon have higher elongation and lower rigidity than fiberglass. At same weight, a laminate of those fibers, with right resin (high elongation), is stretchy but floppy. It will need lower forces to break but more energy (work of force = force x distance) to break than fiberglass. Bonded on a substrat it'll be harder to peel off.
Delamination resulting from shear stress in foam at bond, shear stress increase drastically because of local buckling of skin. So a skin stronger against buckling (stiffer) is an effective way to go against delam.
Sorry for my franglish
lemat:
Well said!
Kind regards,
surfding
The board is done except for screwing on fins and padded foot straps. It is a shape and size borrowed from an Ocean Rodeo Mako kiteboard that I once tried and liked in the surf. It is narrow with huge concave.
Foam - Corning pink Formular 250 = psi 25, density pcf 1.55. $20 from hardware store.
Surface prep - 60 grit sanding followed by perforating with Woodpecker.
Resin - Resin Research 2000.
Schedule - One layer Texalium (gift from friend) on bottom; thick, strong, too stiff to drape around rails; pain in a.. Would not use it again. Two layers of 4oz fibergalss on top.
Verdict - $100. But will it dent and delaminate?
Future - If I like it except that it dents/delaminates too easily, I might try getting the hardware store to order a denser Formular, or I might get some foam that surfding recommends. I would try the aggressive perforating wheel that johnmellor posted. I would try Skinz under more glass to make a shell thick and tough enough to not dent or flex ... thus protecting the XPS from crushing ... thus eliminating what is apparently a chief cause of outgassing leading to delamination.
Thanks all for very constructive comments.
John Laudenslager
[IMG]http://i1191.photobucket.com/albums/z469/Denisesewa/001-28_zpsa7a06e97.j...
[IMG]http://i1191.photobucket.com/albums/z469/Denisesewa/004-17_zpsd113a446.j...
Nice.
I glued patches of cerex on high impact areas to spread the denting forces. Board was stolen before I got a verdict whether this works.
Nice looking board John. Let us know how it holds up.
I like this board. I def think increasing the bond/strenght of the deck is the way to go and probably the only concern (aside from not leaving it in the sun). That's why I use it only as a bottomlayer, holds up fine not 1 dent or delam. I sanded it at 40.
Thanks all. I absolutely will post how it held up. I probably will be using it the last week of April and three weeks in May.
no_rocker - When you said you "use it only as a bottomlayer"... to what were you referring ... the Texalium?
Looks cool John. Interested in seeing the fin setup.
Texallium is really stiff, we use a vac bag to get it around the rails. You might have been able to use a spray glue to hold it down before wetting it out. Haven't tried that, but I have heard about people doing it that way with carbon cloth.
shark - This not being a build thread, I hope others do not mind this off topic. The Mako twin tip that my build is based on had just a fin about the size you see, positioned at both ends on the midline. I aim to ride my board one direction only, with my feet rearwardly positioned like on a surfboard, so the only fins are the ones you see. If this board was shaped like a surfboard then the finnage would be too little. Maybe it is too little anyway despite my board's huge concave and soft rails everywhere. It is an experiment for riding in shallows. The fins are screw in, so I can take one or both off, or get or make somewhat larger ones, or make more holes for more fins, or glass big fins on.
Really I posted here to compare glassing techniques on XPS, and showed my board only so commentators could see that I actually did something. I would be happy to talk more other board stuff with you, but probably we should do it by PM.
Cheers,
John L
001_9.JPG
I saw the blocks in the hsot with the board, so I was wondering if that's how you were going to place the fins. This is all foreign to me since I don't kite or sail board. Looks like you did a good job shaping the board too.
Keep the board out of the sun. That will definitely cause it to bubble up.
Sorry, I use a 2cm XPS bottom in a hollow wooden construction.
I don't think anyone else does this build method, but I think it's a good use for XPS. It makes a lighter surfboard and easier shaping of the bottom and placing of the finboxes.
This last summer after trolling the internet for way too long, I finally went for it and made a surfboard. And then a SUP. And now I want to try again. I decided to go the XPS route partly because it is cheap and partly because of the total DIY aspect of it. I wasn't sure what to do about the delamination factor other than just go for it and see what happens. One day I was telling my father in law about my project and he mentioned this paint he uses as a tile setter, ECO Prime. He said the paint sticks to everything and everything sticks to it. I tested the stuff out on a model and then tried it on the real one.
The Bad: Painting the board adds weight. The texture of the paint makes you use more resin (I think) remember I am new at this. It is a funky grey color.
The Good: The paint definitely sticks to the foam. So far I haven't noticed any delams either during glassing or after some use.
Just thought I would share an outside the box approach. I know it is kind of an odd one. I may post one of the builds as a new thread but didn't think this was the place for it.
No idea why the pictures are sideways! I don't know how to rotate them. Is it a glitch with the new site? If anyone wants to clue me in I would love it, Please. I tried over and over and finally the first one came out the right direction(I don't know why) but the second one never would.
board 1.jpg
board 2.jpg
Interesting. Looks a bit thick. Did you sand the coating before glassing?
I have been looking at a similar concept only much thinner.
Swaylocks Surfboard Design Forum: thoughts & theories ... practical & theoretical
RAIL PROFILE http://bgboard.blogspot.com/2014/03/march-82014-afterr-seeing-recent.html
Sanding the seal coat with all those little bumps is going to be a lot of work. Gotta be careful sanding XPS, it will heat up very fast then expand, and you'll burn through whatever you're sanding. I used a slurry of epoxy resin and micro balloons as a seal coat on my last board. I won't add the microballoons again. I had to sand down my board, but I didn't have quite as much texture. You want it smooth before you laminate it, or you'll be sanding through the glass, or you'll have an extra heavy board with that extra resin.
I have only made 2 XPS boards (can't get EPS cheap enough), but both are sound, no delamination or blowing. I use them in the UK, so cold water, no hot days to worry about, although I took one to Barbados in the summer, still no problem, just kept it out of sunlight and never in a hot car. I read a lot of posts and prepared my boards to avoid the problem as best I could. On my last board, after tests which proved an increase in bonding, I used 4 razor blades arranged in parallel, 5mm apart and showing only a couple of mm to create tiny channels for resin to squeegee into. I primed the board with resin before laminating to fill the channels well, minimal resin used. In tests chunks of foam, as opposed to the top layer of foam, came away in a shearing situation, definitly stronger than just 40 grit. Best results were horizontal to shear direction, but this is across the board, as I was worried that horizontal cuts, although really tiny, could promote buckling, I arranged the scoring diagonally both ways, + & - 45 degrees. First board was with resin research Kwik Kick and the second RR 2000, I prefer 2000. Both boards with s glass 2 x 4oz bottom, 2 x 4oz top + 3/4 deck patch, 2" laps throughout. 2nd board was lightest, although slightly smaller, 5'6 x 19 x 2.5 @ 2.8kg without fins, think I'm getting better at using less resin.
Mat
Foam density and minimum compressive strength will affect sheering and buckling. What density XPS did you use?
Did you sand your gray bonding coat before glassing? Final grit?
Swaylocks Surfboard Design Forum: thoughts & theories ... practical & theoretical
RAIL PROFILE http://bgboard.blogspot.com/2014/03/march-82014-afterr-seeing-recent.html
Stoneburner, Yes, the paint is a bit thick. I wish I would have weighed the board before and after so I knew how much weight is being added. Next time. Also the paint may round out any fine angles you wanted in the shaped board.
I just used the pink Home Depot foam, the 150 sheets for a surfboard and the 250 for the sup. I know someone on Swaylocks broke down how that all equates to density and compression strength but I don't remember who it was.
I didn't sand the primer paint after I applied it. The final grit would be like 45 grit sandpaper.
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