How to Distinguish between Flax and Hemp

Posted by : DIY Shatnez Lab | Date : 10:06 AM | Category : dry twist test flax hemp

BS"D

Problem

Linen, derived from the flax plant, is a more refined fiber of flax and is available in fabric and threads.  Hemp, derived from a Cannabis plant, is also a popular fiber used in fabric.  I haven't yet seen thread made of hemp.  You can find hemp fabric being sold online in woven and knit, in pure or blended fabrics.

When linen or hemp is viewed under a regular microscope, they both exhibit bamboo-like appearance with cross nodes.  How do we then distinguish between the two?

Hemp Fibers

Linen Fibers

Solution

Dry Twist Test 

This test can be used to distinguish between linen/flax and hemp.  Here are the steps I took to implement the test.

1. Extract 3 yarn samples about 5-cm long each from a pure 100% linen/flax fabric and a pure 100% hemp fabric.
2. Soak each yarn in its own small container of filtered water.
3. Warm up the oven to 215-degrees Fahrenheit. 
4. Place an oven-safe tray or dish in it for about 20-minutes.
5. In about 15-minutes, take the wet yarn samples and place it flat on a block of wood, leaving about 2-cm hanging from the block. Take a piece of masking tape and secure the yarn in place.  Repeat this step for the other yarn.
6. Remove the tray from the oven after 20-minutes.
7. Place the woods with the affixed yarns inside the tray and let it dry.
8. Watch how the loose hanging yarn orient itself while drying.

Note: To minimize errors in the test, make sure to leave about 2-cm of yarn loose off the block.  If you leave too much (> 3-cm) or too little (< 1-cm), you may not get an accurate result.

Results

A hemp yarn while drying naturally twists at a counter-clockwise direction, while a flax/linen yarn twists at clockwise direction.

Evidence

  

I also added cotton yarn into the test as you can see.  Cotton fibers twist both ways.