Does number of glass layers matter?

General Discussion
21

Hey Surfingdog.

I’m no expert either.

And you’re right, It would be hard to pull the final layer tight on a tacky lam as mentioned above by others…

 I would not lay the last layer glass on a tacky, nearly kicking, lower lamination.

I lay on the final layer onto two previously “stetched” out layers that are still soaking wet, not tacky so the last layer lays down nice and tight because it’s still suspended in liquid resin, no worse and probably a tighter stretched out total laminate than trying to smooth out 3 layers of cloth all at once… Applying extra layers of cloth to a “tacky” lam was not mentioned by me, although I did say “sticky freshly wet out lam.”, perhaps I should have left out “sticky”

Anyway, As for as pulling my laminates tight :     I initially do this with firm squeege pressure then finish the process by pulling the rail laps tight while applying over 10 psi. of pressure with the vacuum bag…

The laminate gets pretty darn  strong , tight and has a great fabric to resin ratio in the “bag”… Only a pnumatic or hydraulic press can get it much stronger… Certainly not a normal hand lay -up…

I mainly add the last layer separately to strengthen the laminate while at the same time draw out excess epoxy into this final layer from those below. This also helps the peel-ply and breather from over saturating, which reduces their effectiveness in clamping force if they stick at the rails prematurely…

There’s a million ways to glass a board, this works for me…

Got to get off this computer now, take care :slight_smile:

I had an aunt that lived near Manchester, I lived in Stockton on Tees briefly as a child…

22

Hi Kiterider,

Can you please expand on how you pull the laps tight while in the bag?

Thanks

Red

23

 

Hey Surfthis,

I have another question for you.

Talkin’ poly here. When you do a cut lap, say 1 layer 6oz, and tape has been cut, do you baste it or do you sand the edges of the glass down and press it into the foam?

I ask because I just finished a board, clear, no resin tint.  Overall it turned out great but I have a few areas where I got small air bubbles between the laps at the cut lap on top.  

I realize that this is where a pinline comes in handy but I would rather strive to get it right.  

Thanks for any advice

Steve

24

The strongest thing in the stack is the glass. The more glass there is the greater the strength. Equal amounts of glass give equal strength. Of course fibre alignment makes a big difference too. Rapid fall off of properties when the load direction is not along the fibre direction.The difference comes when failure occurs between layers of glass.The resin is just there to protect the glass, keep it all together, keep water out and give it some colour. A very general rule is glass: resin 1:1.5 ratio by weight for a woven cloth. When vac bagging and certainly when infusing 1:1 is easily achieved. I know many professional laminators get pretty close to 1:1 by hand laminating but it is hard.

If you want a really consistant layup infusion is the way to go but it is a fiddle when doing surfboards, however patience pays off and you are never fighting the cure rate of resin.

 

Separation between layers does not add strength. If the "separation" is resin all you add is weight. The slight added thickness will add some stiffness coz Stiffness is a function of thickness and skin properties.

Having just read what I've written the expression that comes to mind is Blah blah blah!!

 

Sorry about all that!

25

If it’s color, it’s better to press it into the foam IMHO. You can baste it and lightly feather it, but you have to be careful or you’ll be able to see color variation where the lap is a little thinner.

Personally, I do freelaps on clear boards, pull the resin onto the deck a little ways with the squeegee so the cloth is nice and tight, then feather the laps down. Nice and clean and no can see!

26

Hey Red.

I’ll try to go through my process.

Building stringerless kite surfboards, I  use 2 different bagging methods. I attach core-cell skins, core-cell rails  finbox inserts and bamboo veneers using a purpose built adjustable rocker table, and a half bag method…

When bagging on the final glass laminates, I use a large full bag that I place the board into after glassing one side at a time…

Becauses I use a peel-ply and breather for this step, and after glassing the bottom for example, it allows me to place the board/ bag back onto the rocker  table and go around the perimeter of the lapped rails pulling the lap tighter and further onto the deck… Using my thumbs I pull the glass/peelply up further onto the deck area. Sometimes you have to switch the vacuum pump on and off while doing this to totally remove any wrinkles in the bag…

Doing this leaves a very sharp edge in the tail area, just the way I like it, with no bubbles under the cloth when trying to wrap glass around hard/sharp rails… It also results in a very tight/flat lap that requires verylittle  sanding to make flush…with the other side ,as the bag compresses the cloth so flat.

I do the same thing when laminating the deck, although I don’t place it up on the table, but as this is the last building step, the rocker is locked in after glassing the bottom and skins…

I realize this all sounds more complicated and fussy, but it’s really not, although there are up to 10 more steps involved compared to just shaping and glassing a stringered foam blank, so each board is more time consuming, for sure…

That’s why these types of boards range  from $700. to over  $1000:

Most kite-surfers have no problem paying this much, because they know they’re getting bomber construction at the lightest weight possible… I build with the end use in mind, strong for jumping, not so much for just carving…

I’m terrible at trying to up load pictures, I need some computer ed. classes…lol

 

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27

OK. Bump this back to the top.

I found the old thread from Oct 24, 2006  (http://www2.swaylocks.com/node/1021713).  Here is what I found from Hank and Graphite Master:

 

"Got a hold of an expert, Hank Johns at GraphiteMaster.
Thank you, Hank. Hopefully I’ll convey your remarks accurately. If not,
please jump in. Your expertise would always be welcomed.

WRT to weight, there is some validity to Multi-layer Lamination
w/Different Weight Cloth (MLDWC). What MLLDWC seeks to do is avoid
stacking weave ridges of one layer on another of the same weight, in
favor of nesting the weave of one weight within the weave of a different
weight. In this way you would get a tighter lamination with less resin
and therefore a higher fiber/resin ratio. (My take: this is good in a
perfect world, where hairs are split, but hey, if it is better and costs
no more and you are building in your garage, why not?). So alternating
different weight cloths in a lamination could be stronger.

WRT to strength, consider Multi-layer Lamination w/Same Weight Cloth
(MLSWC). In this case, shear strength, and thus break strength is
greater because there are more inter-laminar bonds. More shear strength
of inter-laminar bonds is good. You would therefore expect a 3-layer
lamination such as 4/4/4 to be stronger than and equivalent weight
2-layer lamination such as 6/6 because it has more inter laminar bond
strength (more layers). More layers, with lamination weight held
constant is stronger. (Makes sense to me).

My take: In fact, it is the ability of a 2-phase matrix to take up shear
through this bonding that gives it the needed strength when individual
fibers are flawed or just break in use. (Two-phase matrix composition
101)

The example that Hank gave was G10 fin stock. G10 is made up of much
finer weave cloth and is much much stronger. This is required for
sailboard fins where added strength is needed. Surfboard fins aren’t
normally made from this G10. (My take: surfboard fin boxes usually break
before the fin so G10 isn’t needed).

So, in the extreme case, a 2/2/2/2/2/2 would be stronger than a 12 oz
single lamination. But no one but a nut would want to endure that
project. So maybe a 4/2/4/2 for a deck would be good. If you had the
time and inclination.

"

28

Great thread!

Thanks guys

29

 

I kite and I don’t think this is true for kitesurfing.  But I guess that would be another discussion.

30

Hey Fresh.

You’re right, that is a different topic, and I’m sorry if I drifted that way a bit in my responses to the topic here…

I hope I answered the question,  and believe that multiple layers of lighter easier to work with cloth work better, for me anyway…

My construction method takes a lot of time, energy (pumps and stuff) and higher cost materials… I can build a $300-$400 surfboard that you can kite with, anyone can… Will it last if jumped?.. for a while…

I built my first windsurf boards with stringered eps and multiple 6oz.glass laminates, they all buckled when landing jumps, all… I had to glue on skins… They cost more to build this way, it’s a fact…

Check out any online retail store and see what they charge for the big name and custom ( fully jumpable) kite-surfboards, a Naish for example is around $850-$900… The Slingshot/Aviso’s are over $1300!!..

31

I agree on your statements.

Glass = strength

Resin protects glass reinforcement.

Resin rich boards feel strong to the thumb test but tend to be stiffer & brittle & fracture when dinged

Foam density choice is critical to the above applications.

Stronger foam allows less glass to save $.

Weaker foam requires more glass ($) or sustains more damage for light responsive surfboards.

The 2 above sentences is an age old trade off.

Use of epoxy on the new fine celled PU has merit when addressing the previous sentences.

There is a world of common & exotic reinforcements/resins out there… it’s a personal choice what to use.

That’s what keeps it interesting.

Have fun.

32

Thanks for that post Greg…

Oh btw  … I’ve go a roll of 2.3oz for that very reason, so I can go  3.6/ 3.2/ 2.3 or 3.6 /2.3 or any combination of each, but then I’m a self confessed “nut”…")

Multiple thin layers of cloth are strong, smooth, easy to work with, and practical for me, especially if I’ve gone through the added weight /strength and stiffness of installing skins…

Like Dead Shaper mentioned, there are lots of  choices of constuction and materials we can use, and that does make it fun and interesting…

33

Take a length of that 2.3 and with a  helper pull opposite corners until it elongates as far as it will go then drape one of the pulled corners over the nose and the other over the tail and you have X glass or impact glass.  Which, for reasons I still don’t understand, will help avoid a snapped board.  Search on impact glass here.  Just a thought.

34

Isn’t that a bit like using +/- 45 biax glass? I use a lot of biax in boats and simply love the stuff.

35

Yes, it is the same thing.  Maybe not the exact same identitical thing.  But I think a useful imitation.

How is it used in your boats?

36

Yes it makes a difference.  Flex (surfboard stiffness), transverse stiffness (skin indentation), weight, toughness, strength, damping, workability, resin absorption, and interlaminar toughness and strength will be different.  You probably are wondering if it is noticeably different…NO, except fo workability.  Lighter layers are easier to work with.

 

Randomly addressing other comments throughout the thread:

1)While it seems intuitive that non-crimp fabrics are stronger, some literature and tests suggest otherwise.

2)There needs be a lot more discussion about “Toughness” and a lot less discussion about “Strength”.  Toughness is the energy required to break a structure.  Strength is the load required to break a structure.  Toughness is by far the dominating factor in determining if the surfboard will break or not.

3)All surfboards (all composites for that matter) should be built with at least one layer of off-axis cloth.

If you have two layers, the top should be normal orientation, the bottom should be 45deg orientation
(0,90  / -45,+45). 

For three layers,
(0,90 / -45,+45 / 0,90) will be good for preventing buckling and third best for impacts
(0,90 /  0,90 / -45,+45 ) will be second best to mitigate impacts
(0,90 /  -30,60 / 30,-60 ) will be best to mitigate impacts
(0,90 /  0,90 / 0,90 ) will be the stiffest and the worst for impacts, same buckling resistance as the first

Assuming your total cloth weight is 12oz, all of these schedules can be fabricated quite easily for shortboards under 6’6" with a 60" roll of 0,90 4oz e-glass…the exact same cloth that you use on shortboards, but on a wide roll.  Graphite Master sells it and it’s cheap.  Roll the 60" out on a table, lay your board at the desired angle, then cut.

Personally, I think all non-sandwiched layups should be done with three layers and MOST importantly have a -45,+45 layer of cloth IN CONJUNCTION with a 0,90 cloth.  In other words you should NEVER have a layup that has 2 axis of fibers.  That means X-glass should not be used by itself.  By saying NEVER, I mean NEVER EVER.  Even though 99% of surfboards are made with only 2-axis of fibers, this is bad practice and I pray it will soon be obsolete.

  1. Skewing the fiber orientation by pulling on one side, is not the same as x-glass.  When you skew the orientation, you are simply aligning more fibers in the longitudinal direction…making it more similar to warp-cloth.  This is heading away from the benefits of x-glass.  Personally, I would never recommend this practice.

 

More will be coming on this topic in another thread…including more theory, substantiated with tests.

37

 

We can chat here I guess. The other conversation will just continue around us.

I don’t jump my kite surfboards so bomber proof durability has never been an issue for me. I ride strapless and the most air I get is a little hope. It’s your “stringered eps and multiple 6oz.glass laminates” that would interest me the most. I like the look and feel. This is my third season riding an 08 Rawson Quad ( which your older boards sound similar to), but after the abuse it’s taken being thrown in the back of my truck I feel it’s days are numbered. I noticed a few cracks in the glass around the nose where my other boards have banged into it. It’s kind of nice though because it’s giving me and excuse to make my own.

So how did your “stringered eps and multiple 6oz.glass laminates” hold up if you weren’t jumping them? And what did you use for a string?

 

Thanks.

 

Jesse

38

4) Skewing the fiber orientation by pulling on one side, is not the same
as x-glass.  When you skew the orientation, you are simply aligning
more fibers in the longitudinal direction…making it more similar to
warp-cloth.  This is heading away from the benefits of x-glass. 
Personally, I would never recommend this practice.

I think you are aligning fibers in a ± 45 degree orientation  (thats’s what it looks like to me as it lays over my board, just rotate the cloth until you see 45 degrees), which when used with 0 and 90, gives the layup you suggest.

39

 Hey Jesse.

Feel free to  PM. me any questions, it’s nice to talk to other builders that have kiting in mind…

The stringers were 1/8"  marine plywood, it was pretty expensive stuff considering how thin it was, I bought a 4x8’ sheet… It had no voids in the plies which is important for strength, and it featured waterproof glues, hence the marine designation…

 With some of the new 2# blanks out there now, you could build a strapless board that would hold up fine to the occasional olly…

I’d be still tempted to install a 3mm. core cell deck patch for my foot stomping area, but that’s about all you’d need.

You could even inlay a couple of small core-cell or bamboo triangles just at the nose area to resist that abuse you refered to.

If I hadn’t of jumped the boards they probably would have held up fine, I used  6 and 4oz. S glass way back then…

The Rawson quad is a nice board,   I make mine all under 6’ long though, usually 5’6" to 5’9", I prefer them shorter and wider… I have a Jimmy Lewis 6’ board but I never ride it, it feels too big and slow…

I’m building a 5’1’’ trunk board for myself, it’s a beefed up copy of a Cole board, this one I’m going to jump for sure !

I’m going to buy some good 2#eps blanks and shape a few normal ones like the ones you prefer, It sure will be nice not having to do so much work on the core…

Have you considered "timber-flex’ construction using bamboo veneer?, very adaptable to kite-surfboards…

40

Yes, but you are losing the 90 degree fibers.  You are moving the 90 degree fibers to +45,-45 degree directions, which is halfway toward 0 degrees.  Transverse (90 degree) fibers add virtually no stiffness in the longitudinal direction.  As transverse fibers become more aligned with the 0 degree fibers, the transverse fibers add more stiffness to the longitudinal direction while reducing stiffness in transverse (90 degree) direction.  This is what warp cloth does…stiff in long direction and flexible in transverse direction.

Balanced 0,90 cloth will be stiffest in the 0 and 90 direction and most flexible in the +45,-45 direction.  If you add a +45,-45 cloth to a 0,90 cloth, then the laminate will be equally stiff in the 0, 90, +45, and -45 direction.  It will be most flexible in the +30, -30, +60, -60 directions.

The same comments about stiffness can be said for strength, but not toughness.  Sometimes a structure is more tough in the more flexible direction.