For The Record - Carbon Fiber is not Graphite

[tomana]

This thread is titled Carbon Fiber but not all composite guitars are made of carbon fiber. One particular brand is made of Graphite. Though both carbon fiber and graphite are based on carbon, they are not one and the same

I vote to change the thread title from "Carbon Fiber" to "Composite" <---- RainSong

[Doubleneck]

Originally Posted by tomana

This thread is titled Carbon Fiber but not all composite guitars are made of carbon fiber. One particular brand is made of Graphite. Though both carbon fiber and graphite are based on carbon, they are not one and the same

I vote to change the thread title from "Carbon Fiber" to "Composite" <---- RainSong

And the Brand that is Graphite? I guess that is Rainsong cause they say it on their home page, now I am confused?

[Captain Jim]

How 'bout: "Not Wood Guitars"??

That should cover it.

[kramster]

I never said it was...

[sirwhale]

I assumed the "graphite" bit was a marketing technique, when in fact they were made of carbon fibre. If they are in fact made of graphite, I'd be really interested in the technology/science behind it.

Could be a good context for some of my science lessons. Espeically if I had one and took it in. I wish.

If anyone has anything concrete and scientific I could read for this topic, I'd appreciate it. I'm still unsure as to how carbon fibres are able to be woven yet be strong. (I'm a biology specialist)

[Doubleneck]

Graphite is just a marketing term, its really carbon fiber. Thanks to Rainsong for the confusion.

[Earl49]

Originally Posted by sirwhale

I'm still unsure as to how carbon fibres are able to be woven yet be strong. (I'm a biology specialist)

I think of composites as "artificial wood". Nature's composite - wood - is basically long cellulose fibers set into natural resins. Carbon fiber / fiberglass / other composites are glass fibers or carbon fibers set into a polyester or epoxy resin. Different woods have different properties of strength and flexibility because they have different fiber structure and different resin densities or adhesion properties between the resins and the fibers.

Fiberglass tends to use air curing resins (polyesters or vinyls) while carbon fiber tends to use thermo-setting resins (often epoxies of one sort or another) that need to be heated to cure, often heated in a vacuum. So they can be quite strong just like wood can, because the resin matrix holds together the fibers. It can create strength both by simply hardening, and by embedding the fibers in a resin that prevents movement of the fibers relative to one another therefore creating stiffness. (Picture a killer case of heavily starched underwear). The beauty of composites as a material is that we can select the desired fiber orientation and strength, choose the resin for its strength and vibration damping properties, and get very specific lightness versus stiffness to achieve whatever properties that we want. As an aside, my Rainsong WS-1000 has a layer of foam on the inside of the top about 3/16"thick. I figure it is there to better match the internal damping and vibration characteristics to the pure CF top to that of wood, to better replicate a woodier sound. Without the foam providing some damping, the top would ring much longer than wood, giving an artificial tone with abnormally long decay rates compared to wood.

Wet fiberglass or CF has no strength, which is why it can be molded - at least until the resin hardens. In the case of CF, most of the resins won't set up or cure until heated. While a cruder example, it's not that different from steel re-bar making concrete stronger in tension and bending. Concrete is plenty strong when loaded in compression, but has little strength in torsion, tension, or bending. That is where the reinforcing bar (re-bar) comes into play. The re-bar carries the tension loads, while the concrete matrix carries the compression loads, and holds the re-bar in the desired shapes or places.

Hope this helps.

[sirwhale]

Originally Posted by Earl49

I think of composites as "artificial wood". Nature's composite - wood - is basically long cellulose fibers set into natural resins. Carbon fiber / fiberglass / other composites are glass fibers or carbon fibers set into a polyester or epoxy resin. Different woods have different properties of strength and flexibility because they have different fiber structure and different resin densities or adhesion properties between the resins and the fibers.

Fiberglass tends to use air curing resins (polyesters or vinyls) while carbon fiber tends to use thermo-setting resins (often epoxies of one sort or another) that need to be heated to cure, often heated in a vacuum. So they can be quite strong just like wood can, because the resin matrix holds together the fibers. It can create strength both by simply hardening, and by embedding the fibers in a resin that prevents movement of the fibers relative to one another therefore creating stiffness. (Picture a killer case of heavily starched underwear). The beauty of composites as a material is that we can select the desired fiber orientation and strength, choose the resin for its strength and vibration damping properties, and get very specific lightness versus stiffness to achieve whatever properties that we want. As an aside, my Rainsong WS-1000 has a layer of foam on the inside of the top about 3/16"thick. I figure it is there to better match the internal damping and vibration characteristics to the pure CF top to that of wood, to better replicate a woodier sound. Without the foam providing some damping, the top would ring much longer than wood, giving an artificial tone with abnormally long decay rates compared to wood.

Wet fiberglass or CF has no strength, which is why it can be molded - at least until the resin hardens. In the case of CF, most of the resins won't set up or cure until heated. While a cruder example, it's not that different from steel re-bar making concrete stronger in tension and bending. Concrete is plenty strong when loaded in compression, but has little strength in torsion, tension, or bending. That is where the reinforcing bar (re-bar) comes into play. The re-bar carries the tension loads, while the concrete matrix carries the compression loads, and holds the re-bar in the desired shapes or places.

Hope this helps.

Thanks, it´s the "not letting the fibres move relative to each other" that got it for me.

[Earl49]

Sirwhale, the other example that came to mind as I typed that was frozen fabric. Soak some cloth with water and freeze it, and you have a non-flexible composite which could actually have some strength to it - at least until it gets above freezing. I went with the other description first.