Find answers about carbon fiber, fiberglass, aramid/Kevlar and related composite materials. Product selection, ordering, storage, processing, and shipping—all in one place.
What is the difference between carbon fiber, fiberglass, and aramid (Kevlar)? When should I use each?
Carbon fiber offers the highest stiffness and strength-to-weight ratio, excellent for structural parts where weight and stiffness matter (aerospace, automotive, sports equipment). It is conductive, so avoid direct contact with metals like aluminum.
Fiberglass is the most flexible, cost-effective option. It has good strength and electrical insulation and is widely used in marine, automotive, and general industrial applications where budget and corrosion resistance are priorities.
Aramid (Kevlar) provides exceptional impact and abrasion resistance, ballistic protection, and good flexibility. It is ideal for protective gear, cut-resistant applications, and hybrid laminates where toughness matters more than stiffness.
Many projects use hybrids—e.g., carbon for stiffness with a layer of aramid for impact resistance.
What do "1K," "3K," "6K," and "12K" mean in carbon fiber fabric?
The K number indicates how many thousands of filaments are in one carbon fiber tow. For example, 3K means 3,000 filaments per strand.
1K–3K: Finer weaves, smoother surface, better for cosmetic panels and complex curves. Common in aerospace and high-end consumer products.
6K–12K: Stronger, thicker tows, faster layup. Good for automotive, marine, and structural parts where aesthetics are less critical.
24K+: Heavy-duty industrial use (wind turbine blades, large structures). Coarser finish, very fast layup.
Lower K values drape better and give a finer visual pattern; higher K values build thickness more quickly but can be harder to work on tight curves.
What are plain weave, twill weave, and satin weave? Which should I choose?
Plain weave has a checkerboard pattern with balanced strength in both directions. It is stiff and stable but less drapable—best for flat or gently curved surfaces.
Twill weave (2×2, 4×4) is the most common choice. It offers good drape for compound curves, a characteristic diagonal pattern, and a balance of strength and workability. Ideal for automotive body panels, marine parts, and sports equipment.
Satin weave (4HS, 5HS, 8HS) has longer floats and minimal crimp, so it drapes best and yields the smoothest finish. Best for complex molds and visible cosmetic surfaces. Can be less stable during handling.
Unidirectional (UD) has all fibers in one direction—maximum strength in that direction but no cross-direction reinforcement. Often used in combination with woven plies.
What does GSM (g/m²) or areal weight mean? What weight should I use?
GSM (grams per square meter) or ounces per square yard indicates fabric weight per unit area. Heavier fabrics add thickness and stiffness faster; lighter fabrics drape better and suit thin, curved parts.
For most projects, 200–280 g/m² offers a good balance of workability and strength.
What is the difference between dry fabric and prepreg?
Dry fabric is carbon fiber, fiberglass, or aramid cloth without resin. You apply epoxy, polyester, or vinyl ester resin during layup (hand lay-up, vacuum bagging, or infusion). It has no shelf-life concerns when stored dry and is suitable for most hobby and industrial work.
Prepreg is fabric pre-impregnated with partly cured (B-stage) resin. It requires controlled storage (often refrigerated or frozen) and must be cured in an oven or autoclave. Prepreg offers higher fiber volume, consistent resin ratio, and better mechanical properties, but is more demanding to handle and store.
Which resin system should I use with carbon fiber, fiberglass, or aramid?
Epoxy is the preferred choice for carbon fiber and aramid. It provides excellent adhesion, good mechanical properties, and is widely used in aerospace and high-performance applications. Choose epoxy grades suited to your cure temperature and application.
Polyester and vinyl ester resins are compatible with fiberglass and some aramid uses. They are often more cost-effective for large parts and marine applications, though they generally offer lower performance than epoxy.
Always confirm resin compatibility with the reinforcement. Some resin systems are formulated specifically for carbon fiber to avoid galvanic corrosion when carbon contacts metals.
Ordering & Purchasing
Is there a minimum order quantity (MOQ)?
MOQ depends on the product. Many standard items can be ordered in small quantities; wholesale and custom orders may have different minimums. For larger or project-specific orders, contact us at service@bulkcomposites.com or via WhatsApp for a quote and MOQ details.
Can I order custom sizes, weights, or weave types?
Yes. We offer custom specifications including width, areal weight, weave pattern, and fiber type. For carbon fiber plates and tubes, custom thickness, dimensions, and laminate structure can be discussed. Please provide your requirements or drawings and we will assess feasibility and provide a quote.
How long does it take to receive my order?
Standard items in stock typically ship within a few days. Custom or large orders may need additional production time—often 1–4 weeks depending on complexity. We will confirm lead times when you place your order or request a quote.
Do you provide samples?
Sample availability depends on the product. For many fabrics and materials, we can arrange small samples for evaluation. Contact our sales team to discuss your needs.
What payment methods do you accept?
We accept common payment methods including T/T (bank transfer), and others as agreed. Payment terms for larger orders can be discussed with our sales team.
Storage & Handling
How should I store carbon fiber and fiberglass fabric?
Store dry fabric in a cool, dry place, away from direct sunlight and moisture. Keep it in sealed bags or containers to avoid dust and humidity. Avoid excessive heat, which can affect any sizing or coatings. Properly stored dry fabric can last for years without degradation.
What is the shelf life of epoxy resin?
Unopened epoxy resin and hardener, stored at room temperature in sealed containers, typically have a shelf life of 1–2 years or longer depending on the formulation. Check the manufacturer’s datasheet for the specific product. Avoid freeze-thaw cycles, which can cause crystallization in some resins. If crystals appear, warming and stirring may restore usability—follow the manufacturer’s instructions.
How should I store prepreg carbon fiber?
Prepreg must be stored cold—often at -18°C (0°F) or below for long-term storage, or in a refrigerator for short periods. Room-temperature exposure is limited (days to weeks depending on formulation). Improper storage leads to premature curing, reduced tack, and poorer part quality. Always follow the supplier’s storage and out-life specifications.
How do I handle carbon fiber to avoid damage?
Handle fabric with clean hands or gloves to avoid contamination. Use sharp scissors or a rotary cutter to minimize fraying. Support larger pieces when moving them to prevent creasing. Avoid prolonged UV exposure before layup—store in opaque bags when not in use.
Processing & Applications
How do I cut carbon fiber fabric without fraying?
Use sharp scissors, a rotary cutter, or a sharp blade. Cut on a stable surface. For aramid (Kevlar), sharp tools are especially important as the fibers are very tough. Some builders use a hot knife for aramid to seal the edges. Always cut slightly oversized and trim after layup if needed.
Can I use carbon fiber with aluminum or other metals?
Carbon fiber is electrically conductive. When in contact with aluminum or other reactive metals in the presence of moisture, galvanic corrosion can occur, weakening the metal. Use a barrier layer (e.g., glass fiber) between carbon and aluminum, or use non-reactive metals (e.g., stainless steel, titanium) or plastic fittings where direct contact is required.
How can I protect carbon fiber from UV damage?
Epoxy resin can degrade under UV light, leading to yellowing, chalking, and loss of strength. Apply a UV-resistant clear coat or paint (e.g., polyurethane) to exposed surfaces. Some resins include UV inhibitors, but a dedicated topcoat is recommended for outdoor or long-term use.
What is the best way to achieve a glossy carbon fiber finish?
Use a smooth, polished mold with a quality release agent. Place the carbon fiber against the mold for the best surface. Apply adequate resin without excess, and use proper consolidation (roller, squeegee, or vacuum) to avoid voids. After cure, sand lightly if needed and apply a clear coat for protection and gloss.
Can I paint or coat carbon fiber parts?
Yes. Carbon fiber parts can be painted, cleared, or coated. Ensure the surface is clean, lightly abraded if necessary, and compatible with your chosen coating. Epoxy-based parts generally accept automotive paints and clear coats well. Test on a small area first for adhesion.
Shipping
Do you ship internationally?
Yes. We ship to customers worldwide. Shipping cost depends on weight, volume, and destination. Add items to your cart and proceed to checkout to see shipping options and costs before placing your order. For large or complex orders, contact us for a custom shipping quote.
Why does epoxy or resin cost more to ship?
Epoxy and other liquid resins are classified as hazardous materials (hazmat) for transport. They require special handling and packaging, and are often restricted to ground shipping. As a result, shipping costs for these products are typically higher and weight may be charged at a premium (e.g., doubled) in our shipping calculator.
How can I track my order?
We send a dispatch notification by email with tracking information once your order is shipped. You can track your parcel at 17TRACK or on the carrier’s website (DHL, UPS, FedEx, EMS, etc.). See our Shipping Information page for full details.
General
Where is BulkComposites based? Who do you sell to?
BulkComposites is a China-based supplier with headquarters in China. We sell to customers worldwide—hobbyists, manufacturers, fabricators, and businesses in the Americas, Europe, Asia, and elsewhere. We combine a strong supply chain with international sales and support.
Do you offer technical support?
Yes. Our technical team can help with product selection, layup advice, and troubleshooting. Contact us by email at service@bulkcomposites.com or via WhatsApp. We aim to reply on business days as soon as possible.
Can I get a product catalog or specification sheets?
Yes. Visit our Wholesale & Custom page to view or download the product catalog. For custom specs or datasheets, contact our sales team.
Is carbon fiber recyclable?
Carbon fiber can be recycled, but recycled material is generally weaker than virgin fiber and is often used in non-structural applications. Recycling processes (e.g., pyrolysis) are evolving. For now, virgin carbon fiber remains the standard for high-performance structural use.
Why is carbon fiber more expensive than fiberglass?
Carbon fiber production involves expensive raw materials (precursors), energy-intensive processing, and specialized equipment. The result is a material with exceptional strength and stiffness. Fiberglass uses more common raw materials and processes, making it lower in cost. The choice depends on your performance requirements and budget.
Still Have Questions?
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