I was told the other day that if you use poly resin with carbon fiber cloth that there is a reaction between the carbon fiber cloth and the poly resin and that you end up with a glass job that is only 1/2 as strong. I tend to think that if you are going to use the carbon fiber you may as well use epoxy, but I don’t think there is going to be a reaction between the carbon cloth and the poly resin. Can someone clear this one up for me?
Sounds weird. From what I’ve heard the reason not to use poly with carbon fiber is that the polyester will fail long before the carbon does, so you won’t get any additional strength. regards, Håvard
That make since to me.
Hey Bagman, The ploy won’t wet out the Carbon fibers for shit. And weave saturation is what strength is about as we know. Greg Loerh could give you the specifics on it but I know from working with the stuff when it’s time to put it down and the catalyst is working you can’r fool around and you can’t use UV because the stuff is black. I’ve found that you can use poly and epoxy in composite construction you just have to rough up your surface after cures well with 80 grit to put some teeth in it. Hope this helps if you need some extra strength in something you’re laminating. Seaya at the point, Rich
Carbon was designed to be used with epoxy. I’ve used it with both resins and what Havard said above is pretty much true. One of the real advantages to using epoxies is the freedom to use ANY fabric and ANY core material. Greg Webber has brought a lot of interest in flex characteristics to the fore recently on this website. This is a HUGE focus presently in Austrailia and probably presents a real future component in the next wave of high performance surfboard development. I assure you that carbon WILL be part of this, as will some other synthetic and natural fabrics, veneers and core materials.
It is true that optimum saturation of carbon fibre is achieved through vaccuum bagging - Though it has been used on boards laminated by squeegee only. In a couple of cases i’ve seen the strength gain is negated by the fact that the stuff will still crease easily cos’ it’s SO DAMN STIFF! http://www.speedneedle.com.au
There is lots of free info on fibreglast.com, the following is taken from their site, if Im telling you how to suck eggs, sorry I’ll pull my head in see ya. What is Fiber-To-Resin Maximization and Why Is It Important? The reason that composites are used increasingly is the strength-to-weight advantages that they offer. The key to obtaining these advantages is maximizing the fiber-to-resin ratio. The reinforcement (fiberglass, aramid Kevlar® graphite, etc. is not particularly strong in the textile state. As well, thermosetting resins such as polyester and epoxy are quite brittle if cured without reinforcement. If excess resin exists in the laminate, the laminate will have more of the properties of resin only. If too little resin exists, places where the reinforcement is dry will cause weak spots. To optimize the resin content, the entire reinforcement must be saturated with resin with as little excess as possible. The technique of “squeezing out” excess resin to obtain a maximized fiber-to-resin content is the theory of vacuum bagging. How Much Resin Is Optimum? Typically, a hand laminate uses in excess of 100% fabric weight by resin. A refined aerospace composite lamination will obtain as little as 40%. To determine the perfect combination for a given lamination is a sophisticated engineering problem beyond the scope of this brochure but a good target is 60% resin content. It is important to recognize that dry spots are “weaker” than resin-rich areas and maximization of fiber-to-resin is relative to a “real-life” fabricator and his or her ability to improve the parts made.
I remember Blake before he passed away used to use Graphite and vacume bagging. I went to his factory and his boards were all black and astheticly ugly as hell but really light, dont know how strong they were but I imagine using graphite would make it alot stronger than traditional resin and fiberglass. I wonder how you can keep wax on a black board? On a summer day it would melt off just from the walk across the beach.
“The reinforcement (fiberglass, aramid Kevlar® graphite, etc. is not particularly strong in the textile state”. Here’s my 2cents worth. Kevlar is just as strong in it fabric state as it is, afer it has been saturated with resin.With Kevlar the resin is only realy there to bond it to a surface and to hold its shape.Try cutting Kevlar with normal scissors or cutting it with a knife,it is all but impossible.Bullet proof vests are made out of Kevlar which is fabric alone no resin.Having said that polyester does’nt bond to Kevlar very well, vinylester or epoxy are the way to go. I hav’nt had any problems with poly and carbon being incompatable.I use carbon to reinforce some of my longboard fins and have had no problems. I have never seen carbon react with poly. “From what I’ve heard the reason not to use poly with carbon fiber is that the polyester will fail long before the carbon does, so you won’t get any additional strength”. I think this depends on the type of failure. Carbon is very stiff, but it has a low impact strength, so if a carbon surfboard is hit by another board or a rock the carbon will fail wether it is glassed with poly or epoxy.
I think this depends on the type of failure. Carbon is very stiff, but it has >a low impact strength, so if a carbon surfboard is hit by another board or a >rock the carbon will fail wether it is glassed with poly or epoxy. On the other hand, kevlar is bulletproof, therefore a carbon/kevlar mix should provide both stiffness and impact strength. With respect to sun exposure and heat resistance, I’ve read that carbon isn’t much affected by heat (don’t they make race car brake disks out of it ?). However, I’ve also read that, with time, kevlar loses some of its properties due to UV sunrays. Therefore I think a carbon/kevlar board lamination should be protected from sun light (paint, gel coat, tinted opaque gloss coat ?). Then comes the epoxy issue (maybe Greg Loehr has the answer) : I’ve tried once using epoxy (with styrofoam) and I’ve had continuous heat resistance problems with the board. It appears that my lamination tends to softens whenever the board gets a bit hot (and I’m careful not to leave long it in the sun), then it also seams that air in the styrofoam expands with heat which results in delams ranging from 1" to 12" diam bubles. What did I do wrong ? I had great expectancies with epoxy and now I don’t really know what to think about it. I was told that to be strong, epoxy requires a high temp (oven baking) curing phase but then that would melt the foam … Is the epoxy we can use for “traditional” lamination really performant ? Pierre
“On the other hand, kevlar is bulletproof, therefore a carbon/kevlar mix should provide both stiffness and impact strength.” This is true. A carbon/kevlar hybrid cloth is available.I have seen boards glassed with it.The only problem with glassing with kevlar is when you sand the hotcoat you canot sand through to the kevlar. Kevlar when sanded fluffes up and stands up proud of the surface being sanded. Kevlar does have to be covered with something to protect it from UV attack.
I would stay away from Kevlar in a surfboard. Kevlar can lead to delam issues as well as itlikes moisture, meaning it tends to absorb water. If it isn’t protected from UV light, it will lose it’s physicals quickly. Sluggo
Pierre, Sounds like you used extruded polystyrene (XPS). Try expanded polystyrene (EPS), your delam problems will be much less. Also covering carbon is easily done with silver paint available at almost anywhere they have spray paint. The aluminum powder in the paint makes it VERY opaque. Then airbrush on top of that. Some epoxies have low HDT (heat deflection temperatures). This is the reason for the softening. Better systems don’t have this issue.