Sewing tips

Identifying Unknown Fibres

Recently I purchased some fabrics from the bargain section of my local fabric store. The fabrics weren’t labelled with their fibre contents. The shirt that I made from unknown bargain find fabric fell apart the first time I washed it. When I made the shirt, I noticed that it wasn’t cotton, but I didn’t know what the fibres were. Some fabrics are good choices for specific uses and poor choices for others. You need to know the fibre content in order to make this determination. This is an identifying unknown fibres sewing tip.

Introduction

Fabrics can be created from a single fibre (like cotton) or a blend of fibres (like poly cotton) by processes such as weaving, knitting or felting. Fibres are categorized according to how they are created and may be natural, man-made or synthetic.

Natural Fibres

Natural fibres are made from organic raw materials which are processed then spun. Examples include cotton, linen, silk, hemp, cashmere, and wool. Natural fibres are breathable, biodegradable and usually manufactured without the use of harsh chemicals.

Man-made Fibres

Man-made fibres are made from natural polymers such as regenerated cellulose. Man-made fibres undergo more processing than natural fibres. Examples include rayon/viscose, bamboo, acetate, modal, and cupro.

Synthetic Fibres

Synthetic fibres are made from non-naturally occurring materials and are created using chemical processes. Synthetic fibres are not biodegradeable and don’t breathe. Examples include nylon, polyester, lycra, polyurethane (PU) and polyvinyl chloride (PVC).

If your fabric’s fibre content is unknown, there are a few ways to help you determine what the fibres may be.

Scrunch Test

The scrunch test helps differentiate fabrics made from natural fibres from those that are made from man-made and synthetic fibres. Natural fibres scrunch and crease easily and absorb moisture. Synthetic fibres don’t crease as easily and absorb less moisture. Man-made fibres are somewhere in-between with creasing and moisture absorption, so it may be difficult to identify them using this test alone.

Grab a handful of the fabric you are attempting to identify and scrunch it up in your fist. Hold it tight for 5-10 seconds or until the fabric feels warm in your hand as you aim to create enough heat and pressure for wrinkles to form. Release the fabric and examine the results. Fabrics made with natural fibres will be full of wrinkles and creases while those made from synthetic fibres will crease gently or not at all.

You can practise identifying fabrics by the scrunch test by feeling the labelled fabrics in your wardrobe.

I tried the Scrunch Test on some 100% silk and 100% polyester.

 

Wrinkled silk (left) & un-wrinkled polyester (right)
Fabric Hand

Fabric hand is an estimated quality of a fabric and is evaluated by the sense of touch and integrated in the brain as a total value. In simpler terms, fabric hand refers to how a fabric feels when it is touched. With practise you will be able to determine texture, drapability, stretch, wrinkle resistance, etc. Fabrics with a soft hand or fine hand are soft, smooth and fine to the touch and make comfortable clothing. Fabrics with a hard hand are coarse, harsh, rough, and unpleasantly stern. It’s less common to use hard handed fabrics for clothing.

The same fibres can be used to make fabrics with different hands. For example, a cotton blouse and denim jeans both use cotton fibres. The blouse’s fabric will have a soft hand while a pair of jeans has a hard hand.

You can practise identifying fabrics by hand by feeling the labelled fabrics in your wardrobe.

Burn Test

The Sewing Directory describes how to conduct the Burn Test and interpret the results. Pre-wash your fabrics to ensure there isn’t any sizing or other residue from the manufacturing process on it. A small sample of the fabric whose fibres you wish to identify is held over a flame with a pair of tweezers. Watching how the fabric burns and examining the resulting debris indicates the fibre content. I’ve tabulated the results for the Sewing Directory’s 8 types of fibres below.

Examples

I gathered some samples of 100% cotton, 100% silk and 100% polyester to compare with my samples of unknown fibre content. Sample sizes on the order of 1cm by 2cm were large enough and I held them over a candle with a pair of tweezers. I let the smoke from the match and from each sample dissipate before burning the next sample.

My cotton and silk reacted to the flame in the way the Sewing Directory indicated they would. It was difficult to see what my black polyester was doing, so I’m glad I also had a blue polyester scrap to test. It produced black smoke and a sickly sweet smell as predicted.

100% cotton, 100% silk % 2 samples of 100% polyester
2 Thin Fabrics

I had 7 samples of unknown fibre content. The shiny camouflage (below) had a smooth hand and both melted and burned like polyester; producing black smoke and smelling slightly sweet.

Polyester with a soft hand

My Aurelis Summer Blouse came apart at the seams the first time I washed it. I know it didn’t feel like cotton and I hoped it was rayon. During the burn test, it melted, continued to burn after it was removed from the flame and produced a distinctive smell that was different from the smell of either polyester or nylon. It could be acetate or acrylic. I interpret the burnt edge as crusty so acrylic is the best fit.

Acrylic
2 Canvas Fabrics

The orange, white and grey canvas that I used to sew a cosmetic bag and brush roll had a hard hand. It burned quickly, continued to burn after I removed it from the flame and it was harder to extinguish than the other samples. It had a distinctive smell that didn’t smell like nylon, polyester, or acrylic. I did a second burn test, and it smelled like the burnt wood of my match and there was very little residue. This seems more like rayon.

Rayon canvas

The multicoloured canvas that I used to sew a mini backpack coin purse had a hard hand and produced a lot of black smoke during the burn test. It melted and beaded like polyester.

Polyester canvas
3 Camouflage Fabrics

My “US Military May 2014 Operational Camouflage” and unmarked camouflage had a soft hand while the hand of my digital camouflage was hard. The flame consumed the digital camouflage leaving behind neither a crust nor beads. This and it’s yellow flame are suggestive of rayon.

Rayon

Both soft hand camouflage fabrics looked like cotton when they burned (yellow flame with scorching near the flame) and the May 2014 camouflage smelled like nylon. Both have evidence of melting along the burnt edges. I suspect these two fabrics are both cotton nylon blends and the one that smelt of burnt nylon has a higher percentage of nylon in it.

Cotton nylon blends
Conclusion

The Scrunch Test and Fabric Hand will help you identify fibre content while you are in a store. To fine turn your results, you may wish to do a Burn Test at home. Softer handed fabrics are usually better for clothing than harder handed fabrics. You may wish to double-check the best uses for the fabrics you have before committing to your sewing project.

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Tanya

Sewn By Tanya Sewing Tip | Fibre Identification: how to idenify fibres

 

Sewn By Tanya Sewing Tip | Fibre Identification: how to identify fabrics

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