I was perusing Keith's glossary and noticed that S-glass is only 10% stronger than E-glass. No kidding? Is this really the case?
S-2 glass was the first developed for military missle applications. It`s a different glass than standard E-glass and is about 30% stronger and 15% stiffer. Most commonly used to provide greater strength with less weight than with E-glass. S-2 glass is compatible with polyester and epoxy resins.
30% stronger sounds better, especially at twice the price. Thanks.
They say 30% but ive heard its really only 10%. Wonder which one it really is?
That stuff came out about 35 years ago, maybe more.
MIGHT.... 30 % stronger if layed up perfectly by itself.
.... 10 % if layed up on a blank
But........ your actual glass job makes more than 20% difference in strength, so YOU control the overall equation.
And when you dilute with colors, sand thru in spots, cut too deep, leave some dry spots and some too wet, lay your reinforcement layers wrong, don't tie everything together, your glass job has little to do with your materials used.
S-glass, which stands for high-Strength, is stronger and stiffer and more expensive. What is commonly called S-glass nowadays is actually S2-glass. The original S-glass, sometimes called military S-glass because it was developed for military applications, is somewhat stronger than S2 glass but it is extremely expensive, due to stringent testing and certification requirements of the military. There is no chemical difference between S and S2...
S2 glass was developed in the 1960s by Owens-Corning to bridge the gap between E-glass and mil-spec S-glass... Compared to E-glass, S-glass provides about 40% higher tensile and flexural strengths, about 10 to 20% higher compressive strength and flexural modulus, and greater abrasion resistance.
To the best of my knowledge S2 glass is one manufacturer's nomenclature. I put the 10% in as a rough indicator, certainly that's not a hard and fast number but was intended as an indicator only -- quality of the laminate is the key thing. Didn't mean to start any huge debates, but it's fun to watch!
I once had a first hand comparison test when travelling. Two boards, bottom up on a trailer, one 's' one 'e'. Went through a hailstorm. The 'e' was left with hundreds of small dent shatters, the 's' was left unmarked. Percentages of strength gain are hugely dependant on personal workmanship, among other things.
both the 10% and 30% figures are correct ,just depends on which test is being performed ,a while back i said i had more data than you could poke a stick at,well here comes a little recorded data,,,,
im gonna give some figures for carbon e glass and s glass all which had the same tests done on them, most were done with strips of different fabrics of the same weight(4oz e glass,4oz s glass,4oz carbon) ,laminated up to look like rulers of between 2 and 10 layers thick depending on the test ....as a point of interest the tests were done with epoxy resin which can elongate further before the fail ,whereas polyester resin can only elongate 2% before it fails ,so combining it with a fabric that elongates 30% before failure is a waste of time,coz the resin is the weakest link youd just be wasting money ...
tensile strength ; the test peices were stretched till breaking point,clamped securely at each end then continueously loaded with weight till breaking,a large bucket was loaded with bricks till the laminate strap broke.....
e glass; 13 bricks
s glass; 17 bricks
carbon; 18 bricks
flex resistance; the test peices were laid across a gap with a set of electronic scales about 1 mm underneath weight was placed on the samples till they bent enough to make the scales register,a plastic cup with 25 grams lead weights placed in ....
e glass; 225 grams
s glass; 250 grams
carbon; 525 grams
flexural strength; the same test as above with out the scales underneath the samples were loaded till they snapped ,one interesting thing about carbon is it gives little warning before it breaks....
e glass 675 grams
s glass 875 grams
carbon 675 grams
in flexural strength s glass was the surprise package ,with both glass samples they bent a little more each time weight was added till they finally broke,the s glass kept bending and bending along way before it broke ,the carbon was predicted to be the strongest but blew me away how easily it broke ,at first it took heaps of weight before it even bent slightly ,it then bent in tiny incriments as weight was added when it finally broke i reckon maybe a few degrees of flex before it broke without warning ,where as the e glass was almost 45 degrees before it went .
i have more tests but these are the most relevant to this discussion.
so from the above tests you can see s glass is 30 % stronger till breaking point ....
and 10% stronger till bending point.so in reality its 10% stiffer 30% stronger.....
hope that clarifies it
Interesting stuff. Tensile strength is not real important in surfboards. Actually not in most composites and yet this is the standard most fabric companies use in gauging strength. Compression strength is what matters and this is difficult because of two things. One. In glass composites, compression is usually only half of the tensile strength. This leads to difficult imbalance in the strength between the side of the board that is in compression and the side that is in tension. If compression and tension in fiberglass composites were equal, we would see far fewer boards breaking. Carbon fiber raises compression significantly and carbon composites are more equal. This is reason carbon composites can be made significantly lighter.
Second, most fabric companies won't give compression stats because the cloth has to be laminated before you can compression test. This tests the resin as much as the fabric. We had a fabric company in MD use our 2000 resin for their carbon tests because they got better physicals with that resin than with any other. It has to do with the stiffness of that particular resin and how well it matches the stiffness of the fabric. Stiff resins should be used with stiff fabrics. Flexible resins should be used with flexible fabrics. 2020 was actually originally designed to be used with synthetic fabrics with very good elongation. In impact and tension tests 2020 actually does significantly better but I certainly wouldn't say that resin makes a stronger board.
As for s vs. e here's an old post I wrote some time ago. Sorry if it's a little redundant.
As Havard said S glass is the top dog amongst fiberglass. But good tensile strength doesn't really mean much in surfboards. Compression strength does and they (the fabric manufacturers) really can't accurately test compression without a resin to hold it in a compression test. This tests the resin as much as the fabric and different resins obviously will give different results. In practice S glass does give you between 5-10% advantage over e-glass. Remember, this all has to do with strength to weight. So, what this means is that an s-glass laminate of 4 oz. is equal to an e-glass laminate of about 4.4 oz..... maybe. In a typical shortboard this will save you about 2-3 ounces of weight in the finished board and add about $15 -- $20 in costs. Whether this is worth it is up to the builder and the customer.
I have to agree with Greg.He really explained that well.We were using S glass for a while in various different glass schedules and I couldn't see any difference.Resin is one of the main factors(and the foam).Unfortunately the surfboard industry uses super cheap resin (I call it the bottom of the barrel).If the polyester glassers would do what Greg did with epoxy we may have a better product.Go figure eh??