Had a crazy idea that may work to get good wet out ratio less than 1 to 1. could you place folded up resin an a small vac bag with resin and pull vac, this would force resin into cloth. Then unfold and place on skins? or is it not worth the hassel??
cheers
Sounds reall messy! Why not vac bag in the usual way? Or go for resin infusion (sorry you people who are fed-up with me beefing on about infusion!). It is possible to have too little resin in a laminate. Infusion will get you about 75-80% fiber volume fraction which is pretty damn good by most standards. The aerospace boys go down to 85-90% using prepregs and autoclaves but that really costs.
Have a look at some stuff I did a while back…
http://www.photobox.co.uk/album/3882842
http://www.swaylocks.com/forum/gforum.cgi?post=282166;search_string=resin%20infusion;#282166
I remember seeing a pic on here of cloth just folded up in a bucket with a phenomenally small amount of epoxy–Greg Loehr or Bert Burger, if I remember right–reminds me I wanted to look that up again.
Somebody else might have the thread on tap…
youre talking 100 or so grams on a boards that 4 pounds
also handlam is fine . and its okay to use a bit more resin
or else the weave shows and looks a bit dry on low ratios
that okay on personal boards and doesnt effect anything but cosmetics
on a board to sell its best just to use the resin and avoid dry spots
Sabs build beautiful strong,flexi lightweight boards at around 4 pounds
just with a handlam
but yeah that would work for inner glass
it would be tricky to unfold it flat for outer glass
and i guess for inner glass your only saving 30 gram or so total weight
sorry i cant see any point in using infusion
not for a home builder anyway
i just cant see any advantages
That’s all I needed to hear–
Paul–your latest boards look awesome and look like they surf great–
Happy New Year on them
greg
Bert Burger was the guy who showed the folded cloth in a margarine tub.
According to the records, a couple of guys pushing for light weight have experienced problems, including Bert himself. Pin air, leaks, etc have been mentioned. One board was placed in the sun and soapy water applied - it began bubbling. Bert mentioned that some team boards were cosmetically inferior due to pin air from dry outer laminations.
just my opinion greg
im limited for space and equipment and cash
KISS theory can achieve a fantastic easy build
i think the other stuff is valid (especially greatwhite norths method and dan and bennys preform)
just not practical for me
although i tried prefabbing skins and it worked well
thanks for the compliment btw
its good thing you cant see them up close 
Im with Silly.
1:1 is excellent and can be done by hand.
You gotta ask yourself why you want lower ratios to begin with, then weigh to pros/cons, risk/benefit. Its one thing to laminate some non-absorbent material, its quite another to laminate a material that doesnt get along with water. There’s a LOT more required of a surfboard laminate than resin/glass ratios or strength to weight. Generally speaking, a good seal is paramount. Forget the aerospace stuff.
I tried folding like that once and unfolding it back out was a nightmare. Messy, thumb bulges pushed into the cloth, weave stretched apart, areas that were still dry…I can imagine it would be 10 times worse if it had been under vac too.
Rolling it up is marginally better. But to wet out cloth anywhere besides in its final resting place is really done best on a wet-out table and them moved flat & tight with the help of 2 more hands.
The most important thing of all is to only cut your cloth to length if you’re using a wet-out table. That way, you & your helper can lift it by the corners that are going to get cut off anyway, so if you stretch or pull it, you’re not affecting the part you want to use on the board. Wet cloth is way easier to cut too, as it drapes so well. And no stringies. Wet it out, drape it over, cut, and lap the rails. Very easy, totally minimal resin use. Only problem for me can be finding a helper at 11 pm
Edit: I wouldn’t feel right about this post if I didn’t mention the wasted cut-offs. All that cloth we waste is bad enough (how much do we really need to save for fin panels & ding repair?) but to waste resin too is bad. So yeah, I sometimes keep a bit of plastic stapled to my workbench & lay the pieces down for fin panels. That works great as they’re each all wet out so no need for rollers or anything - just another piece of plastic over the top & a piece of plywood with some bricks on top.
But I’ve also made some little ding repair pre-pregs. Thanks to Roy Stewart on this one - the freezer. I cut off the square corners to just under the width of a roll of wax paper. Lay down the wax paper, wet cloth on top, roll 'em up. Put the rolls in a ziplock & into the freezer. They seem to keep virtually forever. Any time you need to do a ding repair, glass on a fin, cap a finbox, fix a toy for your kids, modify a planer (hint, hint )you take out a roll or two. Unroll onto that same plastic that’s still stapled to your workbench and give it a couple passes with a heat gun. Comes right back to life, as if you never left it in the kitchen for a year. I’ve used 'em for all the above repairs. Its great not to have to mix up epoxy for the tiny little stuff…
I think infusion would be awesome - but the setup cost, experimental failures etc would kill the home builder…
For what? to save 100 grams, and a few hours sanding?
Not worth it for me at the moment, but i’m still doing heaps of research into it.
I’ve got a whole heap of ideas and tricks that I’m trying to find time to do test panels for.
Anyone not interested, stop reading here! this could get long-winded!
The answer lies in removing air from the laminate of course.
Infusion runs at near total vacuum, which it why you can achieve a perfect finish.
When you lam a board, and throw it in a bag, there is nowhere for the air that is caught between the criss-cross of the cloth weave and the bag to go - it stays there, no matter how much vacuum you pull, it can’t get out.
With infusion, the vacuum is pulled before the resin is introduced, so the air is able to escape when the cloth is dry.
Wetness seals air in there…
Perforated release film is the “consumable” approach, and it works well, albeit with a little sanding.
The air can escape through the little holes pretty happily.
But how do you get perf release to bend round the rails of the board without pleating and trapping air, or ugly resin lumps forming in the folds?
Prefabbing flat skins works well like this though.
Pre-sealing the wood helps keep trapped air to a minimum also.
So heres a non-consumable approach for prefabbing flat skins:
Lay down a sheet of polythene, or a polycarb/plexiglass sheet with mold release.
Brush your resin straight on to that, as if you were hot-coating a board, spreading in around to get an even film the whole way along. The resin is the same weight as the cloth your about to use of course.
It will be a thin layer of resin!
Then lay your cloth down on top of the resin, and let the epoxy soak up through the cloth, achieving full wet-out.
This technique means that air will be released upwards and out, the cloth is just sinking, as if you threw it into a swimming pool.
Then, lay your wood on top of that. The veneer can be just taped together on the outer face, in whatever groovy pattern you like.
Put the whole lot under vac.
You can vac in against a flat board (polycarb will work by itself) so that the veneer planks are all flush on the glassed surface, and you can fair out any missmatches in plank thickness on the dry side of the wood.
This can be done really quick and rough, as that grain is not gunna be visible.
The only place you have introduced air to the laminate is between the wood and the cloth, and hopefully it will stay there, or even better, be forced/sucked in to the wood by the vacuum and pressure.
Down between the cloth/resin/polythene interface, there never was any air, so that should come out as perfect as the polythene or polycarbonate surface it is pressed against.
Remove that air thats trapped in the cloth is the important bit, as that is where the whole pin holing problem comes from.
Ok, resin ratios and lay-up technique:
Just less than 1:1 with fully wet out cloth is actually easy to achieve!
The problem is, that when the cloth is that “dry”, there is space between the fibres for air to be trapped, as detailed above.
So then, hot coats, 2 pac, etc are required to fill those voids.
As remarked on in an older thread, I count that towards your resin ratio, so your finished board is actually much worse than 1:1 !
It is good though, because the resin cloth matrix, where all the strength is, has been formed properly, is super tight against the board, not a floating bond, and has as little of that brittle, non flexing resin as possible.
It just has extra goop all around it for waterproofing and cosmetics!
I figured out how to easily wet out and unfold the cloth onto the board, and i don’t have any problems with dry spots, even if the lam is not getting vacced.
What I do is:
Use a shallow baking tray, as big as you can find.
Lay a sheet of polythene down in it.
Cut cloth to the size you want - do this on the board, as if you were glassing a PU/PE, allowing for laps, or whatever, but don’t cut the V’s for the nose and tail.
Just remember roughly how much the cloth over hangs, as this is important.
Weigh the cloth.
Fold it up from one end of the board, and fold it to a size so that it just fits into the baking tray.
The reason to use a really big baking tray, is so there are fewer layers of cloth that the resin has to soak through.
Too few layers though, and it becomes hard to get the small amount of resin to wet it all out - like a hand lam with too little resin.
A baking tray size works great!
When wetting out, pour half the resin on the cloth, push it around for a while, letting it soak in.
Then pick up the cloth and turn it over, so the dryer underside is on top. Use the rest of the resin on this side.
That really helps to get the thing even saturated with so little resin.
Try not to force it in, as your just making air bubbles…
Make sure it’s all wet, and you’ll have no dry spots when you unfold it.
To unfold it onto the board, remember which end you started folding the cloth up from, so you’ll be unrolling it from the other end, and finish where you started. Smooth it down with the squeegee as you go.
The trick is to realise that the weave of the cloth stretches and racks around the place a lot when wet, so it’s easy for the cloth to come out shorter and fatter or longer-thinner than the original cut!
So as your unfolding from one tip of the board, stretch the cloth as required so that it is at roughly the same width as when you cut it, the same lap overhang, or whatever.
Don’t unfold too far ahead of yourself! Get the width right, then unfold more.
Doing this ensures that when you get to the other end of the board, the cloth turns out the right length, not stretched too long or anything.
I use a pair of old resiny scissors to re-cut the laps where necessary, remove any hanging strings, and just generally tidy it up, as you’ll never unfold it perfectly.
Now is the time to cut V’s for nose and tail.
Wrap the laps, and run over it all with the squeege so it’s all tight.
If you do have any visually dry spots, theres always a tiny bit of resin left in the mixing cup you can dab on.
See that resin left in the cup?
Thats how much less than 1:1 you got! weigh it then celebrate with a beer… I think 1 beer for every 2 grams you save is
appropriate.
That was pretty long-winded…
Hope I havn’t bored you all to death, but I find it’s the little technique tricks that make life so much easier!
Kit
If you’re trying to save on resin then you will probably get the problems the others described.
If you are trying to save weight then go for vac bagging with perforated plastic and bleeder cloth. It will cost you a little more but give you a strong light board.
thanks crew, good to get feedback
was thinking about inner glass not outside lam as you still need to fill weave anyway. will try kits baking tray method on the next one.
hey benny nice tips on not wasting glass and resin
thanks
and that about wraps it up
thanks kit
that post explains things very clearly
I figured out how to easily wet out and unfold the cloth onto the board, and i don’t have any problems with dry spots, even if the lam is not getting vacced.
Interesting stuff there Kit.
But since we are an opinionated bunch here 
I dont think that baking tray method is all that different than a simple wetout table. Its just a smaller version. Also Im not too crazy about folding glass 180 onto itself. Ive rolled resin right on cloth draped over eps foam and achived better than 1:1…and much easier time of it. No “dry” spots, but plenty of pin holes. FWIW, Ive estimated 2:1 for sanded hotcoat filled glass laminates.
Interesting signature there kit.
So if you have more than one opinion, do you have more than one arsehole?
Kit, I do it similiarly to the way you do it but i haven’t tried it with a cookie tray (I may have to add that to my technique). The key to getting full wetouts is folding the glass properly. On a shortboard there’s no problem, but when you get up to longboard length it won’t wet out properly without wetting the middle (or more often).
Heya Kit,
I’ve pre-fabbed skins in almost the exact way you describe. I’ve found you can get a very light laminate, excellent resin ratios and a void/pinhole free surface finish that requires no sanding at all. It’s perfect; take your pre-fab skins, keep’em cool, wet vac’em on to blank and apply heat for complete contour adoption, turn the rails, a bit more glassing and you’re done. I’ve even gone as far as to use a clear sheet of acrylic so that I can monitor what is going on after the vacuum is applied. The point you mention about being able to remedy thickness inconsistensies in the laminate is perhaps the BIGGEST benefit to this approach; especially if your stuff hasn’t been perfectly run through a thickness planer…or if you wanna shave off 1/2mm here or there…
I’ve also experienced a slight drying of the weave in almost all instances. I’ve attributed this to both resin absorption by the sandwich core (be it wood or foam) and perhaps too much vacuum, pulling the excess resin through the joints. Regardless, if one were using core-cell or the like; something plain (even lightly grained balsa), then the slight dry spots would be completely unnoticeable. When using darker woods, it’s a problem.
That said, I know that the seal is good; I have a slightly different schedule than you that INSURES a void free surface and personally, I don’t think that a <0.5% void frequency in the laminate is going to sacrifice structural properties at all…I gotta buy some corecell…
Nice stuff!
G
Hi craftee
Yeah, I wasn’t meaning that the baking tray thing was really anything different, just thought i’d describe my whole routine in detail!
The key thing I found was the unfolding onto the board part, the first few times I got wrinkles and hideously stretched pieces in the weave, like benny and silly mentioned.
Now that I figured out how to make it work, it’s a piece of piss! good old kiwi expression there! heard that one before?
The roller trick sounds great, may try that one myself!
I’d bet your right about the 2:1 for a finshed board, man those hotcoats add so much weight… even though you sand so much off, heaps stays on there.
I’ve gotta find a way to get the rail glass perfect straight out of the bag!
I’m still having to hotcoat those, but at least the skins don’t need it.
I don’t get a perfect mirror finish, but they are sealed, and it’s ready for the spray finish.
I’m not going to stop using 2pak or other spray finishes, I feel that it’s really worth having that on there.
Gives it that awesome impermeability, and is such labour saver to get the utimate ferrari shine.
I’d swear it adds years to the boards life and value, cos lets face it, looks do matter, and that clearcoat resists yellowing so much, that the value of the board will be retained for much longer.
Kit
Oh yeah, not sure about more than one arsehole, but too many opinions can definitely make someone an arsehole! ha ha
Heres some of the candidates for my next signature:
Some rules to live by:
“Don’t do anyone I wouldn’t do”
“Do unto others before they do unto you”
“Never trust a man who doesn’t drink!”
All jokes of course!!
Gidday Great White,
Good point about the darker woods showing up the dry cloth!
I’ll have to watch out for that when I do some different inlays, or stain the wood darker. Cheers for that!
I don’t expect anyone to give up their hard-won secrets of how they do their boards, but if any of you guys have any ways of vaccing the glass round the rails, without getting wrinkles, a finish that still needs hotcoating, etc, then i’d love to hear them!
take your pre-fab skins, keep’em cool, wet vac’em on to blank
Not really sure what you getting at about keeping them cool, why does that matter?
turn the rails, a bit more glassing and you’re done
So your using thin cloth strips to glass round the rails?
I’ve been prefabbing skins and finishing the rails like that, so there arn’t any laps in the conventional sense.
Do you still have to hot coat the rails to fill the weave, or are you vaccing them and getting them pinhole-free somehow?
Cheers mate!
Kit
re:cool skins; I like to make them the day before I plan to use them and let the resin go only enough so that I get a clean release from the mold surface; the cure doesn’t go to completion then. I find the panels are noticeably more flexible, which helps them adopt curves better at lower vac pressures, then when vac’ing the whole board together, I like to run through a temp cycle where the board cures at room temp for a while, then at elevated temperature for a while. I find the curves stick much better then.
I haven’t had any luck doing rails in a bag, other than to hold the glass down over really tight curves. Still needs sanding, still needs hotcoating. I think the only way you could get it close to pretty smooth would be to tape a layer of silicone sheeting over the wet glassed rail, sealing on to your already finished deck and bottom, and use that under vacuum; that’d get you pretty close, but I don’t know if you’d have pinholing problems.
Other than protection though, is there really a NEED to glass the rail…that’s the real question. Snowboards don’t have glassed rails and trust me; their rails take way more abuse under regular operation than any surfboard ever would…The kiteboards I’ve made have nothin but resin around the rails and they’re doin fine. Just find yourself a really viscous resin that hangs up well! Rails aren’t a big deal anyways; especially if you’re spraying afterwards…you can sand both of them from 60 grit through to 1500wet in about what…20 minutes? And that’s taking your time!
HTH
G
Thanks for you answers man!
I’m with you on that, the rail glass/laps are not critical like on a pu/pe.
I remember Silly having a discussion about that in another thread, feel free to chime in if ya like mate!
The only reason the rail glass has to be there is to tie the solid perimeter rails to the board.
Thats the most vulnerable, high stress seam on the board, just epoxy or glue holding them on will fail, needs cloth over that seam.
But not much cloth!
The cloth doesn’t need to lap round the board IMO, they could meet at a seam on the rail apex, or even fall short of each other and the gap between just be sealed with resin.
Thats roughly the way it’s done on production windsurfers, as far as I can tell.
check this link http://www.carbonart.co.nz/design.htm
So my next idea is to glass the top and bottom outer glass at the same time, then bag it.
I’ve found when vaccing glass round the rails, theres problems with the glass getting sucked off the rail where the top and bottom of the bag meet at the rail apex.
This has been mentioned in many threads, but I havn’t read of anyone getting a good solution to the problem.
I’ve bought some stretchlon bagging film, the stuff thats really thin, and stretches 400% or something.
Havn’t got round to trying it yet, but it might prevent that void on the apex of the rail, and keep the glass tight to the board.
Still will get exposed weave, pin holes, requiring hot coat!
So, to combat that, I think some perf release film could get a fair way around the rails before it starts pleating and causing problems on the compound curves. two sheets, one for the deck and one for the bottom.
Cut it off as far down the rail as it will go before wrinkling
That would leave only a small band around the apex of the rail that needs to be dealt with.
Perf release is pretty cheap, and it takes 2 minutes to sand the little resin nodes off, leaving a perfect surface for spray finish.
I’m trying to cut out or combine steps where ever I can, gotta get these boards done faster!
Having to glass the rails, hotcoat, and sand adds a couple of extra days.
Kit