Technical Specifications

Composite FAQs


Below please find answers to frequently asked questions on our composite products. These are focused on the most common questions our team is asked regarding composites, recommendations, and instructions. Check out our Technical Specifications page for tolerances and guides on our most popular products. Plus you can find more specific technical information related to an individual product on its individual detail page. If you have questions about our order process, read our Order FAQs.


UV Resistance

Are RWC composite tubes UV resistant?

No. The resin systems used in composite materials are rarely suited for prolonged UV exposure. In order to achieve UV resistance, we recommend you select to have us sand the tubing smooth and then you can have an automotive shop paint the tubes to your liking. If your need is for more than 10 tubes, we will happily provide pricing for us to do it for you.

Forming Tubes

Can I form carbon fiber tubing/plate by heating it up?

No. The carbon we offer is made using a thermoset resin chemistry which provides greater stiffness and strength properties. If you want something that can be heat formed, you must look for a thermoplastic based resin system. This is not common in our industry (yet).

Cutting Carbon Fiber
Fabric Uses (Clothing, Masks)

Can RWC dry fabrics be used in face coverings?

No. Our dry fabrics are for industrial use and not for textile use.

Carbon Fiber Stiffness

Which is the stiffer carbon fiber tube:
Unidirectional Tubing, Fabric Tubing, or Filament Wound Tubing?

Unidirectional and Fabric tubing will be slightly stiffer (in bending) than the Filament Wound tubing. Each of these processes inherently produce different tube stiffnesses due to different fiber wrap angles (or lay-up).Filament wound tubing is generally better for torsional (twist) applications while Unidirectional and Fabric tubing is generally better for bending.

How much stiffer is a carbon fiber tube than an aluminum tube?

Carbon fiber is typically 1.4-1.5 X stiffer than aluminum, everything else being equal.

Carbon Fiber vs Aluminum

How much stiffer is a carbon fiber tube than an aluminum tube?

Carbon fiber is typically 1.4-1.5 X stiffer than aluminum, everything else being equal.

How much lighter is a carbon fiber tube than an aluminum tube?

Carbon fiber is 2/3 the weight of aluminum (or 1/3 less).

Tube Finishes: Sanded Vs. Unsanded

What's the difference between sanded vs. unsanded "Cello Wrap (gloss)" tube finishes?

The biggest difference between these two finish options is surface smoothness and visual appearance.


This is offered as our standard finish. The texture of the tube can be described as "ribbed" and is dark gloss black.

Pros: Hard/tough surface, great for general abuse, looks good too.

Cons: Outer diameter tolerance not as easily controlled.

Twill Fabric - Unsanded Cello Wrap (Gloss)

Twill Fabric - Unsanded Cello Wrap (Gloss)

Uni - Unsanded Cello Wrap (Gloss)

Uni - Unsanded Cello Wrap (Gloss)

Filament Wound - Unsanded Cello Wrap (Gloss)

Filament Wound - Unsanded Cello Wrap (Gloss)


Provides a smooth surface finish and a matte gray visual.

Pros: Sanding enables us to dial in an outer diameter however this may distort the pattern on the fabric tubing if a specific OD is requested.

Cons: Sanding removes the "protective" outer layer of cured resin, exposing the raw fiber. This does however provide a paint ready surface so that you can apply any type of UV resistant / clear gloss paint coat.

Twill Fabric - Sanded smooth matte

Twill Fabric - Sanded smooth matte

Uni - Sanded smooth matte | Bicycle Tubing

Uni - Sanded smooth matte | Bicycle Tubing

Filament Wound - Sanded smooth matte

Filament Wound - Sanded smooth matte

Stock Product Finishes

What about other finishes on stock products?

Read about our Stock Product Finish Options.

Filament Count (3k, 12k, etc.)

What does filament count mean?

Filament count is the number of individual filaments that are included in each tow.


Tow is the strand or small bundle of carbon that you see in woven fabric or spools of carbon fiber.


Filaments are the individual carbon fibers included in the tow or strand.

FILAMENT COUNT (1k, 3k 6k, 12k, etc.):

This number indicates the total number of filaments included in a tow. The “k” represents 1000. For instance, a 3k filament count is 3000 individual filaments contained in a single tow or strand.


The higher the filament count, the thicker and more difficult the material is to handle with bends and compound curves. Filament count choice should be determined by the engineering requirements.

Unidirectional Fabrics

Advantages of unidirectional fabric

Unidirectional fabrics have all the fibers running in a single direction. These materials have certain advantages over woven fabrics.


The technician has greater control over exact ply orientation for stiffer and lighter components.


Unidirectional fibers are thinner than woven fabrics, so you have more control over laminate thickness.


Resin content is kept to a more controlled amount due to flatter laminates, which have less void space than woven fabrics.

Disadvantages of unidirectional fabric


It can take longer to laminate a part because the plies are typically 50% thinner than woven.


Edges are more susceptible to fraying and delaminating the length of the fiber.


Unidirectional fibers are hard to laminate on tight inside and outside corners. The fibers are very stiff and don’t naturally bend.


Unidirectional layups do not present the same as woven and don’t have a typical carbon fiber look.

Woven Fabrics

Advantages of woven fabric


Some weaves will conform to compound curves better because of loose weaves and weave patterns. They also maintain adjacent fiber angles while conforming to complex shapes. (Unidirectional fibers are very difficult to conform to sharp inside and outside corner.) 2x2 twill is the most common for good drapability.


Some patterns just look better from a distance and are used to get that traditional carbon fiber look. Again, 2x2 twill is very common.


Woven fabrics resist edge fraying better than unidirectional fibers, especially when damaged. The woven tows will stop fraying as they pass under the perpendicular adjacent fibers. Some designers will place a single ply on the outside surface for durability and cosmetics.


Woven fabrics are thicker than unidirectional fibers, so they build thickness faster than unidirectional layups.


With each ply, you have an automatic isotropic layup with equal stiffness in two directions. (Isotropic: having a physical property which has the same value when measured in different directions.)

Disadvantages of woven fabric


With woven fabrics, there is always equal number of fibers running in one direction as is running in the perpendicular direction. This limits the customizable ply orientation by always including ply orientations in two directions for every ply.


As the fiber is woven, it passes over and under perpendicular fibers creating a slight bend in the fiber. As carbon fiber is strongest when it is straight, this crimping can cause a slight loss in bending stiffness. This is generally thought of as minimal, but in some structural applications, it can be a very important distinction.


Woven fabrics will require a little more resin content to fill in all the gaps between the woven tows. Typically, it is about 5-10% more resin for woven fabrics. This can add weight and change the structural aspects of the part.

Typical Weave Patterns

What are typical weave patters?

There are quite a few different weave patterns. Here are the most common.


Each strand is woven over one perpendicular strand, then under the next, then the pattern repeats.


A twill weave is 2 strands over two strands and then under two strands. However, the adjacent strands are staggered by one strand to create a diagonal affect.


These patterns or typically a plain weave pattern but use a single tow that is spread extra wide to create a very broad tow. This has specific benefits:

  • Reduces the total crimping of the weave to increase the structural aspect of the fabric.
  • Reduces ply thickness to help control total part thickness.
  • Reduces resin content.
  • Mimics a 0° and 90° unidirectional layup with a single ply.
  • Offers excellent cosmetics.