The type of laminant or reinforcement fabric to use in your project depends on the project. An effective laminant needs to:
- Be strong and flexible (or stiff) enough to withstand the estimated stresses (loads)
- Weigh no more than it has to
The most common types of laminants are fiberglass cloth, carbon fiber cloth, aramid (Kevlar), hybrids, and CSM (fiberglass chopped strand mat). What's the difference between a laminant and a laminate? A laminant is the reinforcement fabric you wet out to create a composite laminate. The laminant is the fabric you start with, the laminate is the final result.
To maximize strength, it’s important to position the fibers in the laminant so they run parallel with the expected loads on the finished laminate. Any fiber reinforcement that's not aligned with the applied loads can separate from the resin holding it together, creating tiny cracks which will eventually cause the laminate to fail.
Keep in mind that a strong laminate has more fiber in it than resin, and when it comes to resin, you want to use only enough to wet out the fabric—no more. Excess resin adds weight, doesn't improve strength or stiffness, and is a waste of product.
- Epoxy resin - Used in layups instead of polyester or vinyl ester resin due to its strength, flexibility, abrasion resistance, moisture resistance, chemical resistance, and durability. Note that some epoxy hardeners cure more clearly than others—an important consideration for clear coat applications, such as wooden canoes and kayaks.
- Polyester or vinyl ester resin - Less expensive than epoxy resin; also not as strong, and more brittle than epoxy resin. Polyester resin is used to wet out CSM because it dissolves the binder in the CSM completely so it becomes transparent.
Laminants can be nonwoven (unidirectional - with the fibers running in the same direction) or woven. Woven laminants come in various weave patterns (e.g., plain, twill, satin, etc.) that affect:
- Ease of wet out (wetting out the laminant with resin)
- Dimensional stability
- Mechanical strength
- Conformability (also called 'drape')
In general, here are some things to keep in mind when choosing a laminant(s) for your layup:
- Nonwoven fabrics such as unidirectionals lay flatter and carry loads more efficiently than woven fabrics.
- Woven fabrics wet out well, with some weave styles wetting out more readily than others.
- The lighter the cloth, the easier it is to shape.
- The heavier the cloth, the stiffer the laminate will be.
More details on how loads affect laminates, weave styles, and other information to help you choose the ideal laminant(s) for your layup.