Hey Basque Kook, you can do whatever you like, no prob.
I think Balsa just mentioned epoxy resin on the off chance that there are guys out there (not you but other guys) who are looking to build a more ding resistant board without adding weight.
BTW, I recommend you skip the following quote.
[Quote=sanded.com.au] Here is the interesting aspects of basalt fiber. In its’ raw neat form without a matrix (resins), it is only about 12% higher in strain-to-failure than conventional e-glass. Now 12% doesn’t sound that impressive, but as you know in composites, it is. Here’s where it gets really cool…when you saturate it with epoxy, the strength properties grow from 12% higher than glass in strain-to-failure to 92% higher. Most surfboard builders don’t think about this, but it is really important to try to match a fiber’s elongation % with the matrix elongation %.
This is why Basalt should be looked at for the real functional use in Surfboards that takes a beating. Basalt fiber is a perfect harmonic marriage with epoxies (Hence why we recommend using epoxy to get the trues strengths in all our advanced composites (Carbons, Kevlar and Basalt).So when basalt and epoxy load up, they fail as a unit instead of two lower energy failures - meaning they hold in together as much as they can until they finally fail… together
[/quote]
I wouldn’t lump all epoxy glassed boards in with the surftech type construction.
I’ve been doing epoxy glassing over mostly PU cores for several years, sometimes choosing heavier density foam on those shapes that work better with some weight. I did do one ‘longboard’ type midlenght with a 2# eps core a few years back and just glassed it heavier; but I didn’t like the feel so I won’t be repeating that experiment. These days you can get PU blanks in the lighter densities - not quite 2# EPS light but closer. I just don’t have any incentive to go with EPS unless I aiming for a liteweight board.
Besides - as McDing said a while back - shape comes first. There’s not much point in putting the elaborate TechnoViking glass job over a poor design or a poorly executed shape.
I absolutely agree. Only thing is most surfers up here don’t know much if anything about “S” Cloth and won’t pay the up charge. I have gone back to BGF cloth for a bunch of different reasons. BGF is superior when teamed with a good Epoxy and Poly or EPS core. I‘M lovin’ Marko.
Thanks. Thats great info and advice. I think though as it is only my second board I would like to stay with cloth and polyester resin. In the future though I will definitely try it.
S Glass should be use with époxy because of elongation to break match as well explain un sanded write. Biaxial can be use for some reasons, i use it a lot, but with lower longitudinal strengh and can add lot more weight than expected.
@ basque kook: if you’re really wanting to try basalt, go for it. That said, the general pracice with any non-glass fibers is to put them underneath the fiberglass. There are various reasons for doing this. (Obviously, the glass stays clear and doesn’t obscure the look of your exotic reinforcement.)
Having said this, you’re taking on a couple unknowns simultaneously, and as someone new to boardbuilding are exponentially increasing the risk of building a dog.
My 2 cents: I’d just go with double 4-oz on the bottom and call it a day. Wrap both layers around the rail, stagger the length of the laps. Boom - stronger bottom and stronger rails, minimal weight gain.
Have fun with whatever you decide. That’s what it’s all about.
One other thing. I understand your wanting to stick with poly for now as it’s what you are familiar with. Eventually, though, you really ought to give epoxy resin a try. It looks like you have access to good quality surf-specific epoxies. Keep everything else the same (blank, fiberglass weight) and simply switch the epoxy for the polyester. It won’t feel like a surftech, and it won’t develop shatter dings as easily.
Yes this place has everything you could possibly want at hand as they also are a supply shop
The problem I usually have isn’t shatter dings. It´s depressions with no cracks usually about 1/2 dollar size - if anyone remembers what a 1/2 dollar coin looks like lol-
Question- would replacing regular 4 oz E glass with 4 oz S glass be harder or make any changes in the way I glass it?
Couple of things I see in your posts to comment on…
“I want my next board to have a very strong bottom as that is where I always get my dings but want to do it with the least added weight.”
“The problem I usually have isn’t shatter dings. It´s depressions with no cracks usually about 1/2 dollar size”
If you truly want to get stronger skin to avoid the pressure dents you need to think about a composite skin/shell as Lemat mentions. I have made many balsa veneer boards (compsands) and they are the best at reducing pressure dents. A board made using a light PU core with a fiberglass/balsa wood/fiberglass skin/shell makes a very strong board. Something in the way the wood manages to absorb some of the impact and spread it out a bit more than just glass fiber. I think a 1/8" layer of balsa is close to about a layer of 12 oz glass, so depending on the fiberglass you use, you could end up with a sking equal to 20 oz of glass, but much lighter. I add a wood skin to the decks of boards I make that have a light EPS core. It helps keep the pressure dents to a minimum. Other guys here use a combination of different fabrics to get similar results. You need to do vacuum bag laminations with these composite skins. If you just do a vacuum bagged lamination, you will get a lighter and stronger shell. I’ve use balsa from 1/32" up to 1/4" thickness, and prefer 1/16" and 1/8" thick veneers.
i know viral, sometimes i go to, i live at 10km. As sharkcountry explain, if you don’t want dents you need stiffer skins, sandwich fiber/wood is the one of best way to achieve it with low weight. but it’s a more exotic build. if you want to stay with “old” tech stay with Eglass and poly resin and as said go with 2x4oz separate lam instead 6oz. lam one layer4oz, let kick, lam second layer 4oz, this way you will use a bit more resin than 2 layers at once but you will increase thickness and so flexural stiffness of skin, i.e. more dent and buckle strength. An improvement with this tech is to lam first layer on the rich side then to spread microspheres over up to saturation then to lam other layer. this way you build a chip micro sandwich, more thickness for low weight had. there is specific micro volumized inter laminates kevlar mat layers for prepeg build but at high price.
Thanks. I think the veneer is a great idea for future boards once I get the basics down but for now why not 2 layers of 4 oz S glass instead of E- glass? Won´t it make it more resistant to pressure dings?
have ridden S cloth exclusively for well over a decade, before that warp glass…S cloth dents much the same as E cloth, however, it is much better at resisting shatters and fractures, so S cloth boards age much better.
Frankly don’t understand why E glass remains the standard, when the upcost for S cloth is so minimal compared to the upside.
There have been extensive tests run between S-Cloth, E-Cloth and Carbon Fiber Cloth. In some tests the S-Cloth ‘outperformed’ Carbon Fiber and at a much lower cost.
I think your idea of using double 4oz layers of S-Cloth makes perfect sense. It will give you added strength and ding resistence at a fairly low price increase.
Worth noting however is how S-Cloth (and carbon) actually perform in those tests. Neither was much better in preventing dents. That is more a function of your inner core or your sandwich composite skins. S-Coth and Carbon do however each have high tensile strengths. If you can imagine what happens when a board actually breaks you can see how a board glassed with S-Cloth or Carbon will be stiff but more resistent to snapping… until they do. Many people have mentioned the “catastrophic failures” that occur when these materials finally give way.
hey basque kook you are french or spain ? if french i could explain it to you clearly in french, it’s my day job to explain mechanic design.
Sglass are slightly stiffer than Eglass, Young modulus= tensil stiffness modulus, with resin, in thin coats there is not really difference. Sglass can stretch near double before break so final tensil strength is double. But for it you must have a resin with an higher elongation than fiber. poly is not able even iso ones, most epoxy yes.
From what I am getting from the group in general is that:
1- S2 or other new fibers will increase shatter strength but not pressure ding resistance
2- pressure dings depend more on foam density and resin
3 increased lam will increase pressure resistance but also weight
4- epoxy on PU or EPS would be better for pressure ding resistance as would veneer
As a noob I am sticking with PU and am not ready to use epoxy
My question goes back to basalt- does anyone think that basalt would have any greater resistance to pressure dings? From all of the above info it doesn´t sound like it would.
depend what is pressure dings for you : dents (enfoncement) or dings (trous). for dents it’s skin flexural stiffness the key, so for same glass pe resin with is stiffer than most surf epoxy is better, sglass wich is slightly stiffer is slightly better too, carbon is the winner. for dings it’s shear strength of skin the key, here epoxy is better Sglass too but with epoxy, kevlar and other plastic fibers with right resin are winners. foam density in range we use, from 1.5 to 3 lb plays a lesser role compared to skin properties, a little for dents, near nothing fo dings
Enfoncement is the right word. They are depressions Without cracks. My epoxy factory boards -surf tech- never get them. Why is that? Epoxy or foam or something else?
Depressions are related to skin thickness. You can appreciate this with the simple thumb test that no one is supposed to do but everybody does when they visit a surf shop. The bottom of the board yields to much less pressure than the deck, which has a skin that is twice as thick (1 layer of glass on bottom versus 2 layers on deck). The surftech boards have a lightweight sandwich skin that is I believe 1/8" thick, which is why they are generally pretty resistant to pressure dings. It also leads to the whole board being very stiff, which affects the ride.
Shatter dings come from polyester resin’s inherent hardness. This hardness makes polyester easier to sand and polish. It also makes it more brittle. Conversely, epoxy is a little more elastic (I mean at the microscopic level). It’s able to absorb small blows without cracking. This quality is often referred to as toughness. (Bear in mind, I’m probably butchering some of the scientific terminology, but hopefully you get the idea.) This elasticity makes it a little more challenging to sand and finish epoxy. Like most things in life, there’s a trade-off.
