I’ve noticed a few different bag materials out there and am wondering which is most preferred by board builders here on swaylocks.I’m also curious as to what is your favorite “recipe” for sandwich construction and or compsand?All input and opinions are greatly appreciated as I would love nothing more than to succeed on my first sandwich construction/compsand board.I haven’t decided which I want to do first,but will try both in the very near future.
Jesus should already know?
I like the cheap O bag o matic. sold by Fiberglass Supply. I think the bag is like 1.25 per yard. I buy 20 yards at a time. bags last a long time. when you get a hole you just put a smidge of duct tape.
Bag long time, love you long time…Joe
favorite bag? A dime bag. duh
Well, if she’s kind of ugly, she gets a brown paper . Really ugly, I get one too. Super
duper ugly, she gets a plastic trash bag, and I run away.
Burlap for puppies in the creek.
Now for the surfboards -
I just did my first, 1/8" corecell top and bottom with 2 oz glass/ epoxy to bind with the foam.
Bottom - 6 oz carbon fiber with 2 oz pigmented over it. another 2 oz clear to cover the rice paper.
2 - 4 oz deck
Here are some hints. I learned the hard way. Carbon fiber over fusion fin boxes - must vacuum
bag because the carbon is too stiff to follow the contours.
Same with wrapping the rails. You think it looks great, all nice and tight, you turn your back,
and it pulls up because its too stiff again. Need the vacuum bag!
Other lessons at my expense. If you pull the resin off too hard on carbon, turn your back
and ten minutes later, you get all these bubbles/ wrinkles. It seems that the carbon will work
with you. then slowly creep back to do what it wants.
Also if you pull off the resin with too much force, you get these little white spots where the cloth dries out.
Lastly on the carbon fiber - if you sand the into weave, it goes spotty. The white foam shows through real quick.
paint the foam black first!
Next hint - two layers of corecell are 1/4". A nice thickness for the nose. Stop the eps about 3
inches short of the tip. Use 3 or 4 layers of 6 oz between the corecell. You end up with a bullet proof
flexible nose.
It’s 6’-6" long 21" wide. 2 3/4" thick. It’s coming in around 7 pounds.
Last hint on sandwich construction - add bananas to the peanut butter and jelly. White bread falls apart
when spreading the beanut butter if you use the chunky stuff.
This thread will be treasured for years to come…I can feel it.
Good info,thanks! 
I like the Nylon bagging tube and bag clamps available from acp-composites.com
http://www.acp-composites.com/acp-vbes.htm
The time and headache saved using this combo justifies the cost.
The 36" tube is great…since 2 out of 4 sides are already joined…no stupid mastic/duct/whatever taping plastic tarp together.
I bought a 15’ roll…combined with their bag clamps which are far superior to the same mastic/duct/whatever taping to get those
open ends closed, I can scale my bag size to suit the board I’m building and with one end already clamped, the second end is closed
up reliably tight within seconds once the board is in the bag…no walking around with my ear to the bag looking for the weak link
in the tape.
I can’t even count how many times I’ve pulled vacuum on this bag so far this year…still going strong.
Personally, I’m over the compsand stuff…veneers and epoxy lams on the deck of a 1.5/2lb EPS or PU blank and I’ve got what I’m looking
for in a board: durability
Rail buildouts…forget it.
Building out balsa/paulownia skins…expensive and a time sink.
Anyone ever use the “vacuum storage bags” from home depot?
I use 2 mil drop cloth. It is sealed with the cheapest caulk from wal mart $1 per tube. Wall mart sells a good breather cloth in their fabric dept for $2.79 per yd. I dont know what the intended use in sewing is. It is good for vac bagging. I do all my vac bagging into hard molds. The caulk is better than bagging tape when you are attaching the bag to a mold’s flange. It does not dry under vacuum and since it’s cheep it doesnt stick well, this allows the bag to peel up easily and cleans up easy with a wet rag. Also caulk allows the bag to slide into all the corners of the part as the vac is pulled. The vac pulls the caulk into the leaks. The only problem is that the bag is useless when the operation is over. It becomes a messy bag of wet caulk.
Don’t know much about vacum-bagging, but that is one of the better ideas I have heard in awhile. Not very green landfill wise, but at the price of 2-mil. plastic and calking; very economical.
You can’t go wrong with the ACP guys. Their website has pretty much everything you need. Use the small vacuum port, their 36" bag, the peel ply with release agent will make things easier, and the quick lock seals. Go to Ebay and look for a medical evacuation pump with a guage. I’ve got a Gomco that will pull 23 hgs for days, got it for $40. You can get poly tubing for cheap at any hardware store. Walmart’s fabric department has thin poly batting for quilting for breather.
ACP also sells http://www.acp-composites.com/acp-mats.htm which is a great way to tune a boards flex without the hassle of using thicker materials. It’s cheap, easy to cut and form, and doesn’t absorb insane amounts of resin.
A typical laminate schedule on a 2lb. eps blank on the deck would be Kevlar mat, carbon mat at rear toes and heel, 12 oz. double bias biax with 4 or 6 oz. warp on top, perforated release with peelply only no breather. Pull vacuum at 10 hgs for 4-6 hours depending on your temperature. Bottom was single 6oz. only or double 4oz. You can also use 1/8" corecell with 2oz. under with 4oz. over for the deck instead of the extra glass. But corecell is very expensive, glass is cheap.
You can also make a thin bog with resin and glass bubbles and apply a very thin coat to the foam to seal the pores. It prevents the foam from pulling too much resin making your laminate dry.
You’ll get a somewhat ugly board cosmetically with the Kevlar layup that is vey light and strong. If you did a fair job on the shape it will ride like a light, strong, fairly shaped board. If you did a poor job on the shape you will end up with a light, strong…well you get the idea.
In the end I found that shape was more important than the construction and ended up with a few bomb proof dogs. A hand layup with 4 and 6 oz. was faster, cheaper, and much much easier to do.
Quote:
Anyone ever use the "vacuum storage bags" from home depot?
seen something similar to these and wondered about their use for making composite fins and SUP paddles… they are about the right size…
as for bag material, good ol tubefoil of low density polyethylene, big suck for your buck…
I bought a 3 pack for $5 at Harbor Freight (sorry guys… not Home Depot) Haven’t used the for fins yet.
bag; free poly bagging from Home Depot that is located by the checkout for wrapping up your timber purchase with. May or may not be available at your local HD; I know it is at mine. Only good for one or two pulls, but goes in the recycling bin when I’m through. Free. Moderately fragile.
recipe; 0.75 lb/ft3 EPS core. tapered (6mm wide at the tip and tail, 12mm in the middle of the board) western red cedar rails; not easy to do, but adds noticeable flex where you want it while keeping significant stiffness between the feet. core spackled with ultralight spackle prior to adhering the skins. 3mm A400 corecell deck and bottom with 2oz glass between eps and CC. extra layer of 2oz around the periphery (1-3" in from the rail) of the board, where the rail meets the sandwich material to better distribute forces from the deck to the rail without cracking. 2oz bottom glass with a patch through the fin area; more to provide protection when installing and removing fins from the boxes than anything. 4oz deck glass with patches under the front foot and back foot. Fin boxes set in corecell inserts in the core of the board. Exterior of the board lammed by hand with decent sized laps to lock in to the “interior” layers of glass. final board weight including boxes, no fins is right around 5lb for a 6’2" x 21.5 x 2 1/4" modern quad “fish”.
pretty damn bulletproof; as strong as I’ve needed it to be…had it out under kitepower; no dents. ran it in to the rocks; no dents. didn’t hold up to a freight train drop to a rocky bottom at Rincon (finbox failure), but easy repair. Didn’t hold up to the American Airlines baggage monkeys at the Miami airport where it seems as though they ran it over with a baggage cart, but then again…what would have? Hands down my most “winning” construction method tried thus far…and I’ve tried a few different recipes.
above recipe is pretty flexy. for bigger surf, chances are you’re going to want a stiffer recipe than described above. you’re better off getting that stiffness through the use of stiffer panels (higher density corecell, or stiffer material alogether like HD balsa, or paulonia or cedar or poplar ply) than through higher density EPS. Increasing the amount of glass you use won’t have as significant an effect on stiffness as increasing the board thickness, but will have benefits in terms of durability. The “glass inside glass outside” stipulation for a “sandwich” board is over-rated; if your panel material lacks strength, then yeah; glassing the insude is pretty imperative; if your panel material is strong enough to not split under rider loads, then the interior glass is just a nice way to get a good, solid, even coat of epoxy to insure good bonding to the eps. Likewise, you could simply use gorilla glue; application in a thin, even coat is a different matter.
higher density eps will limit flex in a much more noticeable way than higher density panel material. increasing the thickness of the board will limit flex in a much more noticeable way than changing your materials out. crowning the deck excessively will also limit flex; flatter decks are good for flex. You can crown through the middle of the board where your chest goes for paddle efficiency and flatten the deck towards the tip and tail if you want to limit flex through the middle and carry extra volume along the centreline.
I strongly advise goofing around with a vac bag and some of your materials. vacuum bagging will completely changet he way you think about contructing a surfboard. there are alot of ways to lock in tension where you might want it, and to keep “structural tension” to a minimum where you don’t.
think about trying to build a strong, impact resistant, flexible shell around a marshmallow and you’ll get on the right track. just like an egg though, when the shell cracks be ready to make an omelette.
hth
g
btw; pm craftee; he’s in Fl and will know where you can source the stuff you need.
Now that is an excellent read.
Gold.
Listen closely to that info guys, it’s all good.
lot’s of good info on this thread.
that was a gem GreatWhiteNorth
Dime bag? What are you…a rookie? LOL
No less than a quarter…of anything!
And that’s just for the evening!
HA! HA! HA! Just kidding … sort of
Hello Jesus, its been a while since I built a board and when I was building them I didnt have the benefit of seeing other swaylockian recipes, nor did I explore many recipes. So my recipe was one that succeeded and worked but I didn’t take it much further than that. Others such as Paul Cannon have clearly experimented a lot more with coming up with the really tasty recipes. Although I don’t feel that my recipe matches what the guys at compsand.com are achieving I will offer some opinions on how to do the cooking.
You mention success as one of your aims. Sandwich boards (I think this means the same as compsand) have more potential to go wrong than traditional construction. Failure risk can be reduced by spending more money on easy to use bagging materials, practising and performing peel tests.
I can see that it is fun to experiment with cheap alternative bagging materials and something I havent done, but my very first sandwich board did succeed and some of this is attributed to using the stuff from acp-composites.com as mentioned by afoaf and DMP . ACPs nylon vacuum tube is just right, the quick-lock seals easy to use. Vacuum experts use cheap material such as taffeta for peel ply, but they know exactly when to peel off the ply. With ACP composites blue release peel I could leave the bagged board for a full day and still be able to peel the ply without any risk of it tearing off my lam.
What I mean by practising is things such as the following: firing up the pump with a chunk of EPS inside the bag and discovering what level of vacuum will over a few hours crush the EPS and what vacuum it can tolerate - its important to give it a good few hours of vacuum coz EPS will initially withstand a fair bit of vac and then slowly over time get the life crushed out of it. Then progressing to using the full size EPS core and stacking on a piece of skin material and wrapping it with the peel and bleeder or whatever your recipe involves, but omitting the glass and epoxy. Then stuffing the wrapped assembly in the bag, getting the bag sealed and then getting it all under vacuum. Just wrestling with something this big will show up all sorts of issues that you will need to solve in your individual way before launching into a real setting epoxy under vacuum situation. I remember once I was experimenting with reducing the cost of the peel by using strips held on with masking tape, but the tape didn’t stick to the peel properly and tape catches on the bag while sliding it in and the bits of peel started coming off - if I had been doing it for real with resin it would have been a disaster but I avoided failure with this dry run. I used to time myself with a clock during these operations too, to ensure that I could achieve all this before the resin sets.
By peel tests I mean taking chunks of core and skin both in isolation and sandwiched and lamming them under vacuum, then attempt to do things such as peel the glass from the skin or prise the sandwich shell from the eps core. Using a variety of recipes with the peel tests - eg sealing the core, priming the skins, doing really dry lams, really wet lams etc. If the glass comes away from the skin readily then thats bad. One of the problems with the peel tests is that the small chunks are so much easier to manage than a full size board that they can sometimes give better results than the real board in terms of peel resistance.
And now some thoughts on the cooking, I’ve been contemplating doing this again and there are some things that I would still do. Although my boards looked really rough I was very meticulous with mixing the resin. All weighed on electronic kitchen scales and stirred for a total of 3 mins exactly. First stirred it in one pot for 2 mins then tipped into another pot scraping down the sides of the first pot and another min of stirring. Overcooking maybe but every batch of resin I mixed set properly.
I spent a lot of time researching the project and downloading information from all sorts of non-surfboard building sources. I had some theoretical formula type stuff which I didn’t understand, but those equations were based on lam strength both sides of the skin. So although I’m sure GNW knows from experience that the inner lam is less important I got a lot of satisfaction from knowing that I had a good bond there. Sandwich boards can snap so it makes sense to me that some effort is spent there, even if the outer lam is more important for resisting dents. What I found was that an unsealed eps core would suck resin from the inner glass. The glass doesn’t need much resin (and one of the points of bagging is to squeeze excess out of the glass), but what this means is that excess resin ends up getting sucked into the EPS instead of filling the pores of the skin. The bond to the skin is thus reduced. Sandwich theory is based on the skin being a sandwich rather than the eps core having a good bond to the shell. But actually by sealing the core a good bond will be had to the core anyway and my sealed EPS peel tests pulled EPS beads away rather than separated cleanly.
I also downloaded good boat building sandwich practises. What they said is that priming the skin is important to fill the pores and get a good bond to the glass. Priming does however add weight. My choice of sealer and primer is resin mixed with micro-balloons for both situations. The micro balloons reduce the weight. If I was to do it again and had limitless resources I would use the Resin Research flexible resin for the skin priming.
Because I evolved to using a wet-out table the lam is fairly dry even before the vac. But with a sealed core and primed skin the bond is good. I would use a wet out table again, but this is partly coz I can’t glass properly and I find the table easier and don’t get resin on the floor.
Outer lam was also bagged for weight reduction and also wetted on the table. Priming the skin with micro-ballon slurry therefore applies for the outer lam too. Excess weight will be sucked out by the peel and bleeder cloth.
I would also bog/fair with micro-balloon slurry rather than a solid resin hot coat for weight reasons. Micro balloon filled resin is more brittle than straight resin so I suppose flexible resin for the fairing would be nice but I never had any cracking problems with micro balloon filled boards.
then I’d paint the whole lot with acrylic surfboard sealer or 2 part LPU paint - I used both successfully. Although one of the boat building recommendations was to put an epoxy gloss coat over sanded micro balloon fairing before the painting I didn’t find this necessary - I suppose surfboards aren’t in the water for as much as boats.
fairly complete instructions for my method are on this thread:
http://www.swaylocks.com/forum/gforum.cgi?post=194577;#194577
but lets not forget Bert Burger’s great built for swaylocks thread:
Thanks MrJ,that was a very informative and relaxing read,we actually did a dry run today,we vacced a piece of eps to the rocker table and did a system check,it went very well,now if my veneers would arrive I might could make a board. 
Dry run - smart (and patient!)
We got the vac sorted to hold 7". Used aquarium parts (T-pieces), tubing from hardware store and a bit of vaseline to seal joints.
Dropped in the foam inserts for the fin system, Lammed up the bamboo veneer using 4oz cloth on the 1.5lb EPS core and built a bag around it using 0.015" (0.4mm) plastic sheet from hardware store and double sided tape. Perimeter epoxy stringers so no rocker table because the blank could hold its shape.
Damn setup could not pull enough air to compensate for tiny leaks (we think it was the bag crinkling at the tape edges, especially at the nose).
A fair amount of duct tape later and a second external bag (thank goodness for slow epoxy times) and we were able to hold 4-5" of vac - not really enough to pull the top deck into the nose kick, but tight in the rear vee and concaves (no rail wrap, as in the WMD thread).
Definitely needed breather material to help airflow to the pump and also needed non compressible material at the pump entrance (we used rubber stuff that compressed too much and pulled the bag into the vac tube, sealing it off).
Lessons
-
Should ha done a dry run (naa - too impatient to see it all together - this board WAS the “dry” run!)
-
Slightly thicker bagging material to lessen crinkles at the taped edges (and leaks, we think)
-
Mainly - bigger fridge pump (we used a pump from a bar fridge and it simply couldn’t pull enough air to maintain vac in a big bag - fine for a small bag)