Does "S" cloth really make a stronger epoxy board?

General Discussion
1

It seems I read somewhere in the archives that Greg L suggested that “S” cloth didn’t provide any real benefits for surfboards. I may be wrong in my recollection, but I’m getting ready to order some more cloth and wanted some input.

I’ve been using 6 oz “S” cloth on my boards but find wetting 2 layers with minimal resin sort of a pain, so I was going to get some 4oz “S” cloth instead. Just use 3 layers of 4 oz instead of 2 of 6 oz.

Anyway, some of you may have done major research already and I’d like to hear the results. Everything I read says S cloth is superior, except for the one post from Greg (whose opinion I highly value) I seem to recall stating otherwise.

Not factoring in the price, is S cloth the stuff or does it really make a difference? I’m not talking about poly resin here, just epoxy.

mahalo

2

I think I’ve read this too - and, like you, I got curious. And I’m going off memory now, but I think what it came down to is this: s-cloth is about 30% stronger than E with poly, but only about 5% stronger with epoxy. This is because (good) epoxy resins will flex more than polyesters and the failures in E cloth with poly had more to do with the resin & not the cloth. And S cloth actually flexes less than E, so it matches up with the flex characteristics of the poly resin better than E does.

That’s not to say that its bad with epoxy - just that you have a better match for poly resin using S than using E.

Say you built 400 boards - 100 each of E & S, poly & epoxy.

You might end up, under normal surfing conditions, with 40 snapped E cloth polys, 10 snapped S cloth polys, 15 snapped E cloth epoxies, and 10 snapped S cloth epoxies. Same result using S with both resins - but more downside to using E with poly. (I have no idea what the real results would be, nor do I want to discuss or project them, I’m just trying to illustrate…).

Another major benefit of S is that its much more clear. I use E with epoxy, because I actually want the flex because I think the wood skins will absorb potential failure-causing energy better than the resins do anyway. But the laps are a bit green & visible, even with just 4 oz. I wouldn’t freelap a white foam board with even 4 oz E and epoxy, you’d see it. I have no idea why, but it does seem that epoxy makes the greenish (like volan) color of E show up more than poly does.

Although, I recently did a poly/poly board too, with the 4 oz E. I did cutlaps because there was some color on it, and the places with no color certainly are visible with a bit of green…

Sorry to drag this on, but I guess your considerations should be not only whether 5% less likely to fail is important to you, but also the expense of the cloth, and the time involved in cutting laps (with E) add up to you wanting to get S instead of E.

3

S cloth is better when you don’t have to consider the price. The finish will not be as crisp as E or hexcell warp. The dry lap cut of the cloth seems to have more strings hanging off than E and people say it is harder to wrap the rails. But starting off from the get go uising it I knew no difference. I started using it with windsurfers back in the day and continued using it with surfboards. But in order to save costs with the surfboards I no longer use it and have only noticed better finishes, more profit and no complaints with durability. Depending on where you buy your cloth it can be twice as expensive as E glass or warp. If you live or have friends in Texas where hexcell is made you can get end of roll s glass for dirt cheap. If you are buying just enough for a board or two don’t waste your time at the factory, just spend the money at the retailer.

4

Howzit Puna. I did similar research a while ago and actually got a pm from Mr. Loehr back when he was still very active on this site. What he told me was not that s-glass and epoxy was not stronger but that the manufacturer’s claims of 30% stronger were not accurate He gave a figure more like 5%.

I went ahead and used S glass because 5% stronger is…stronger. And the additional cost was only about $20. Check out U.S. Composites (shopmaninc.com). They had the best price on S glass that I could find.

ps Oh, and another thread unanimously hailed 3 layers of 4oz as stronger than 2 layers of 6 oz , so it sounds like you’re going in the right direction.

5

Yes, US composites is where I get my s cloth from too. Best price around.

6

I thought s cloth was designed for use with epoxy and therefore much stronger when used with it as opposed to used with poly resin.

7

I don’t know if 3x4 oz. is stronger, but it will most likely end up lighter. The weave is tighter so you’ll need less resin for the fill coat.

8

3 x 4 will be stronger. This ‘‘opinion’’ is based on personal experience, going back a ‘‘few’’ years.

9
Quote:

It seems I read somewhere in the archives that Greg L suggested that “S” cloth didn’t provide any real benefits for surfboards. …

That’s close enough. The small gain in (impact?) strength is not worth the pain. S-glass actually changes the resin slightly which makes it harder to sand. Lots of good info in this thread. …and if Barnfield will chime in. You can use a slightly heavier glassing schedule with epoxy and be stronger without s-glass.

I won’t use it anymore. It’s just not worth it. Add any imperfections in the hotcoat like a little orange peel effect, and you’ll hate it too. At well over twice the price, don’t waste your money.

10

[=Blue]Aloha guys

I have mentioned this in the past on Swaylocks which is what Ozzy is commenting on.

I haven’t done tests recently with S Glass so I can’t state this as absolutely current with all brands but in the past… here is the deal with S Glass.

S Glass has two important differences from E Glass. One is the actual chemistry of the glass itself. This glass chemistry is said to be stronger then E glass and I accept that. The E in E Glass, by the way, stands for Electrical! As it was originally designed for use in electrical insulation.

All glass fabrics have a “finish” applied to them to allow the “resin” to soak in and fill the fiber structure more quickly. And the finish must be ideally designed for the Resin System used.

The second difference is that S Glass has a finish that in the past, caused excessive promotion of polyester resins. This made the resin harder, which appeared stronger, but was also more brittle. This promotion of the resin also bleeds into the hotcoat from the lamination. This is why S Glass boards have a well known and negative reputation among sanders as being very hard to sand.

So in testing a laminate of several layers thick, which is the way the tests are typically done, S Glass will appear to be much much stronger. But… much of that strength will be in compression or impact strength gained due to the harder resin, and not really the stronger glass material.

Additionally, Glass fabrics have specific characteristics in their construction. Things you have to consider are…

What the chemistry of the glass material itself is.

What diameter the filaments are and how long they are.

How many filaments are used to make up a strand.

How many strands are used to make up a Yarn.

How are the strands shaped

How are the strands wound together to create Yarns.

How are the Yarns wound (twisted) together.

How are the Yarns that form the Weaves woven .

What kind of finish is on the fabric

Is that finish compatible with the Resin being used

Etc, etc.

Then of course there are the issues of how well the lamination is applied.

Is it pulled taut.

Is it crushed tight (thin) to the foam and not floating on a bed of resin.

Is there just enough resin to fully bind and fill all the filaments and weave with no excess and also no dry spots.

How many layers are used

How well are they nested

How are the laps cut

Etc, etc.

As you can see there are many factors that will effect the strength of any glass job. Just choosing the fabric and lamination schedule can be overwhelming if you aren’t fully educated in the materials, their make up, their use and the outcomes created by it all.

Even if S Glass’s “glass material” is superior it should be tested and rated in some fashion that is relative to the kind of use surfboard makers would use it in. But published “tests” aren’t reflective of that as far as I have seen.

The excessive promotion of polyester resin that many sanders have noticed when sanding S Glass boards, surely throws a giant monkey wrench into the whole calculation! You might as well just glass with a hard brittle resin like common, Finishing Resin.

S-Glass in the past was primarily made to work with Epoxy resin (and there are many kinds). That is why there was a slight milky weave appearance to the lamination if it was laid over a darker substrate. The incidence of refraction (light moving through it) of the S-Glass was set to match Epoxy not Polyester. Presumably the Finish was also, and that’s why something in it was promoting the polyester resin.

Or maybe it was intentionally set to promote polyester resin so that the “tests” would look better or boards would seem stronger as they would resist dents and dings, but would break easier as the tensile strength was destroyed in the process.

Remember that when some part of the complete board, like the fiberglass, is said to be 30% stronger. That doesn’t mean that the whole finished board will be 30% stronger. A 30% stronger glass fabric might only make the finished board 5% stronger when completed. Surfboards are an integrated composite structure and the final strength will be be dependent upon every contributing factor. To wind up with a 30% stronger board, each contributing factor would have to improve by 30%, not just a single factor!

Plenty to consider and discuss here boys… have at it!

11

Add any imperfections in the hotcoat like a little orange peel effect, and you’ll hate it too.

I’ve never experienced this effect before.

S-glass actually changes the resin slightly which makes it harder to sand.

Are you refering to poly resin? The only time I found my boards harder to sand was when I let my epoxy hotcoat cure several days before I got around to sanding them, but I don’t think that it was the s cloth as much as it was the cured epoxy that made it difficult.

I think that I have some e cloth around here someplace. If I can find it, the next time I glass a board I will make a test piece of e and s cloth with epoxy and do some kind of bending/break test to see what the difference is. It will be primative, but should shed some light on the subject.
12
Quote:

…

S-glass actually changes the resin slightly which makes it harder to sand.

Are you refering to poly resin? The only time I found my boards harder to sand was when I let my epoxy hotcoat cure several days before I got around to sanding them, but I don’t think that it was the s cloth as much as it was the cured epoxy that made it difficult.

Yes, but it seemed to be a little harder to sand with epoxy also with the same cure time.

Quote:

I think that I have some e cloth around here someplace. If I can find it, the next time I glass a board I will make a test piece of e and s cloth with epoxy and do some kind of bending/break test to see what the difference is. It will be primative, but should shed some light on the subject.

I’m looking forward to hearing the results and any other feedback. But the deal is, I look at higher tensil strength (stiffness) as a flex killer IMO. Which kind of defeats the purpose of using eps/epoxy, other than lightness. - Relating to small to medium wave shortboards, which is what I make the most of. Fish, guns, funs, logs, tow’ers, etc., are a totally different story though. Sort of.

My field of experience with s-glass is rather limited, therefore my opinion is skewed. I engineer a small amount of flex in and out of my shortboards through the materials, glassing schedule, lam technique, and even the rail lap. So the way I look at it is, at double the cost (retail), plus the extra stiffness, it’s just not worth the pain of using it. If I want a board to be more impact resistant (that’s the desired gain?) then I will just add 2 to 4 ounces to the total glassing schedule per side and have a stiffer, stronger, more dent/ding resistant board without the pain and expense of s-glass.

Thanks for the chime BB. You said it better than I could ever hope to.

13

Bro,

There so many combinations you can do.

I use E cloth all the time. S cloths are stronger but more expensive.

When you try to sell a custom board, your custome can choose between cloths.

I woulnd use them for stock boards, too much dinero sitting around.

The trick here is no matter how much oz u put on the deck or bottom, the key is to always have 12oz around you rails and laps.

That will make your board strong.

Why making the deck 8oz if is going to dent anyway, if you notice all the boards tend to brake toward the bottom because it carries less cloth oz’s.

So my combos are 6x6 most of the time and I make my laps longer.

My boards come out super light and strong.

I shaped over 2300 boards and maybe 10 broke as far as I know.

Most of my riders hate epoxy, is not the stronger thing in the world.

Although doesn’t kill the enviroment like poly resin. So just use variety of products.

That will keep your customers happy and always wanting to try other things.

Rich

14

Is S cloth stronger?

Yes. In tensile tests.

Is Greg L correct in his comment?

Yes. Failures in tensile strength is not a major board strength issue. Greg knows, boards primarily fail/break when laminates get compressed/buckled/creased and tensile props play little/no role there…thats why he made that comment. Gotta do your homework as they say :wink:

It also depends on what your definition of “stronger” is. If youre trying to make your boards more break resistant, then a stiffer laminate is the call, which has very little to do with the tensile strength of the cloth that is spec’d by the mfg. And, even with good stiffer lams, youre still dependent on the foam’s ability to deal with certain stresses. Strength is only as strong as the weakest link.

Having said that, I like S cloth…the strands ARE stronger in tension (you can test this yourself) and the overall cloth feels stiffer than E, which makes good heel dent resistant cloth when the right resin (stiff epoxy - ie RR2000) is used. Btw, you can learn a lot about a cloth with a cheap microscope…or just your hands and eyes.

15
Quote:

Does “S” cloth really make a stronger epoxy board?

High performance “structural” glass (S- or S-2 glass in the USA, R-glass in Europe, T-glass in Japan)

Comparing comparable E-glass from Owens Corning and S-glass form Advanced Glassfiber Yarns.

Typical Tensile Modulus, Msi (GPa): 12.6 (87) for S-glass vs. 10.5 (72) for E-glass.

Typical Tensile Strength, ksi (MPa): 665 (4580) for S-glass vs. 500 (4350) for E-glass.

Elongation to Break, % : 5.4 for S-glass vs. 4.8 for E-glass.

Density, g/ee: 2.54 for S-glass vs. 2.49 for E-glass.

16

To use it in a board you have to buy it first. It’s really just where you want to draw the cost effectiveness line.

FiberglassSupply.com

The cut length of enough cloth for a single board (4-15/yds), 30" wide/price per yard

(This is just an example.)

  • 4oz E - $3.14
  • 4oz S - $6.82
  • 6oz E - $3.72
  • 6oz S - $8.32
17

I buy my cloth by the role (125 yds) so I get a better price. For me, If I use 10 yds of 6 oz. for a 9’ longboard, it only cost me about $30 more to use S cloth.

About a month ago I had a guy drop in on me and I didn’t even see him coming. We totally smacked rails. I could see on my board were we hit because it was scratched a little. He suffered a minor ding, but none the less it was taking on water and had to be fixed. I use epoxy and probably more glass and he had poly, so there were more than several factors in play, but makes me wonder.

18

Sure. That was only an example. I buy E by the roll also. So when a customer requested S, I would buy small amounts which made it ridiculously more expensive for a microscopic gain in strength. If you and others feel it’s worth the extra money and trouble, more power to ya. Just not me. I’ve heard epoxy in general is more ding resistant with the same glassing schedule. …unless you glass them thin (by request) like I do. Also, too much flex kills a board, so you can’t over do it. I and many people would rather live with some pressure dents on the deck and have an ultra-light board for small waves. I build travel boards for Costa & Mex subtly different. Shape & glass. Of course my Tex boards have been to Costa & Mex with great feedback, and I have shipped S-glass boards to the east coast with glowing results. Many more orders to come from the same customers. But my point is, my opinion is very slanted so you should take it as such.

The most important thing to keep in mind is what the gurus say, not me. And test result numbers can be very deceiving when you try to adapt lab results to a surfboard application. It’s something to consider along with all the other golden info posted in this thread.

Edited for accuracy and brevity.

19

“S” glass is stronger no doubt,but in it’s strength lies it’s weakness…HUH ? you say?

I have glassed several boards w/ Ssss,and found it is very ding resistive compared to “E” glass.Now here’s were it gets tricky…When you normally would get a pressure ding w/ E , S doesn’t,because it has such great memory and strength, but the foam underneath still gets a good wack,eventually the foam depresses and unlike E which follows The S stays intact and creates…what?

…DELAM.Herb

20

Thanks for your input Herb. Did you find that these delams would spread or just stay delamed right under the impact?