This is the last series in my summer fibres series and I have to say it has been a highly educational process. I have learned a lot by researching all these fibres and have been given a lot of food for thought when considering what material to use for my knitting and sincerely hope that this little series was helpful and interesting to you too.
Hemp is a variety of Cannabis (not to be confused with marijuana which is another variety altogether) and has a long history of domestic cultivation. Other than fibre it was amongst other things also used for paper, sails, animal bedding and lamp oil. The production of hemp has declined a lot in the last century but it seems to be an upcoming material again.
How hemp yarn is made
Hemp grows from seed and is an annual plant which some farmers tend to use as a rotation crop. It grows best in mild climate with a humid atmosphere and likes well drained and rich in nitrogen soil.
The crop is ready for harvesting when the plants begin to shed pollen which (when using the hemp for fibre) is around 70-90 days after seeding. The harvesting is done by a specific harvesting machine and from what I gathered during my research the machine differs from other harvesting machines (e.g when using the hemp seed rather then the stalks)
The next step is retting which is either done in the same way as linen (read about it here) or by leaving stalks in the field for up to six weeks for retting. This process loosens the fibre and naturally removes pectin which functions as a binding agent in the hemp plant that holds the woody inner fibres and outer bast fibres together. During this time the stalks are turned repeatedly. The process also releases a lot of nutrients back into the soil. When the retting is completed the stalks are baled up to allow easier storage and transportation.
After the retting process the next step is to remove the woody core fibres from the outer bast ones for which a sequence of rollers, also called breakers or a hammermill are used. Afterwards the fibres are ready for spinning. They are typically twisted together to form long continuous threads.
Pros and cons
Hemp is a very resilient plant and does not require the use of much pesticides making it a somewhat more environmentally friendly crop than others discussed in this series. It shares many qualities with linen including the characteristic of becoming softer with use, being a strong fibre, resistant to moths, rotting and mildew, and breathable.
However, it is very inelastic and doesn’t stretch much. When using the chemical process to retting it becomes a less environmentally friendly product.
Hemp and hemp blends
From this list I have only worked with one yarn but I have tried to find a good selection of yarn companies and blends.
Isager Plant Fibre (ramie, hemp and bamboo)
Rowan Hemp Tweed (wool and hemp)
Bare Naked Wool Hempshaugh Lace (merino, hemp and silk)
Hemp pattern ideas