Hemp fabric is excellent for dyeing with. See our instagram for lots of examples of dyeing on hemp fabric. We do frequent experiments with our tea towels, which we think are ideal for working with with and marketing dyed hemp products.
Whenever working with a new material, it always helps to learn as much about it as you can. If you have worked with linen before, you are in luck. When it comes to dye, hemp works pretty much exactly like linen. That is because they are both made up of bast fibers, which are structural fibers used by the original plant to hold up the stem. Since stalks of hemp can be quite long, and contain no wood, these fibers need to be strong.
Unbleached hemp is a gray or yellowish color. In our catalogue, we refer to it as "taupe" and do much of our block printing on this lesser treated fabric. We love the natural, raw look of it. We have found that this raw fabric works well with synthetic dyes, but for brighter colors or more saturated natural dyes it is important to remove some of the color first.
It's important to avoid using chlorine bleach on hemp fabric, so no Chlorox! Hemp fibers are held together by pectins that dissolve in chlorine. This leads to a weak, damaged bond between the fibers and rough, crunchy fabric.
Our products are available already bleached. In most cases, if you plan to dye the fabric we recommend the cream color fabric. Like linen, if you dye it completely white, it becomes stiff and "crunchy." The cream fabric seems to be at just the right stage of being ready to take dye and being properly soft.
If you want to do your own bleaching, or say you buy some cream towels and decide you want white, the process is fairly simple:
- Start by "wetting out" the fabric, get it completely soaked in plain tap water
- Add a pint of peroxide (common 3%) to a pot and add warm water. Heat to a simmer.
- Add your fabric and heat for 10 minutes. If, after 10 minutes, you want your fabric to be lighter, add more peroxide and continue for another 10 minutes.
- Rinse all of the peroxide out of the material and dry it.
Preparing the Fabric for Dye
Like all natural fibers, hemp fibers are coated in waxes and require pretreatment to accept dye. If you want to dye hemp fabric, the first step is to wash and then scour it.
To prepare the hemp by washing, use a neutral detergent, like Synthrapol or a dishwashing liquid. Some detergents can leave a residue in the fabric that can prevent absorption of the dye. If you are unsure about your detergent, make sure to thoroughly wash it out, possibly by running it through the washer an additional one or two times without soap.
We have found the best and simplest method of scouring hemp before dyeing is to heat it in water in a solution of calcium carbonate. Calcium carbonate is sold in stores as "baking powder" or "soda ash." Swimming pool supply stores can be a great place to get soda ash at a good price.
Weigh your fabric and then weigh the soda ash to get an amount of 1-2%. So if you have 1 kg of fabric, you will want 1-2 grams of soda ash (1 pound fabric would require 1/6 to 1/3 ounce of soda ash). Mix that soda ash in a pot of water and heat it on the stove to a temperature of 180-200 degrees Fahrenheit. Add you wetted material to the hot water. Maintain the temperature and stir occasionally for at least 30 minutes.
After scouring, rinse out all of the soda ash from your fabric. You will know the soda ash has been washed out when the water running off of it is no longer cloudy.