Tips Tuesday- Determining Fiber Content (aka Playing With Fire)

When starting a sewing project, it is important to know the fiber content of the fabric you are working with. Fiber content determines what kind of care methods you should use. Some fabrics are easy to recognize by appearance and touch, but often it is not that simple.

The best thing you can do is to check the tag or ask about the fiber content when purchasing fabric. But if that ship has already sailed (which is often the case if you are a fabric hoarder like me) then it’s time to put on our lab coats and conduct some experiments.

Cottons and linens can be recognized in a wrinkle test. Crush a small piece of fabric in your hand, a cotton or linen fabric will remain wrinkled when you release it.

wrinkle test cotton linen

The best way to determine, or at the least narrow down your fiber content is to conduct a burn test. Basically, the way a fabric burns will greatly narrow down the possibilities of what it’s fiber content is. Be aware, some fabrics are treated with dyes or finishes that may alter the fabrics flammability. Blended fabrics will burn in the fashion of the predominant fiber, and are hard to determine in a burn test.

Cotton, Linen, Flax, Rayon

These are all cellulose fibers and will burn bright with an afterglow, leaving a fine gray ash and have the scent of burning paper.

fiber burn test 2

Wool and Silk

These two protein fibers have a slow burn. They char and will curl away from the flame. Both have an odor of burning hair or feathers, although the smell is stronger with wool. Protein fibers will stop burning when removed from the flame. The ash they create is black, hollow and can be crushed into powder.

fiber burn test 1

Polyester, Nylon, Acrylic, Acetate

These are synthetic fibers, which means they will melt when put in a flame. They have a chemical odor and when cooled the burnt edge will be hard and plastic like.

Polyester and nylon will stop burning when removed from the flame, while acetate and acrylic will continue to burn quickly.

fiber burn test 3

A neat trick for determining acetate is to place a scrap of fabric in acetone nail polish remover. Your acetate fabric will dissolve in the liquid.

Now we all know playing with fire is awesome, but if you are going to conduct a burn test please do it responsibly. Conduct your burn test in a fireproof container, hold your small fabric scrap or thread with tweezers, and be sure where you are is well ventilated, or better yet go outside.

That being said… Have fun playing with matches!