How to Prep Fabric for Dyeing: Scouring

Check out the water after boiling my supposedly clean sheet!

As usual, I’m taking my shibori challenge right to the deadline. One important preparatory step to dyeing is a cleansing process called “scouring.” I’d never heard of this before now, which may be why all my casual attempts at dyeing thus far have not turned out so great. I spent my weekend scouring so I can move on to dyeing. And then on to sewing! Yikes! I’m really behind.

Scouring is deep cleaning of fabric or fiber. Scouring helps assure even color and good penetration of the dye. Cotton in particular needs scouring, even if it is brand new from the fabric shop, because apparently it is full of hidden waxes and oils. In my case, I’ll be using an old top sheet for my experiments, so it certainly needs lots of help.

Cotton and wool are scoured differently. I’ve never scoured wool, so am not going to cover it here. I understand it is also a washing process, but done with cool-ish water, so as not to felt the wool, and gentle soap. Linen also needs scouring, but I know even less about that.

My primary sources for this are:

• The Art and Craft of Natural Dyeing: Traditional Recipes for Modern Useby J.N. Liles
• The Handbook of Natural Plant Dyes by Sasha Duerr

HOW TO SCOUR COTTON

You need:

1) A big non-reactive cooking pot, big enough so the fabric will not be crowded. I used our enamel canning pot.

2) Sodium Carbonate aka Washing Soda aka Soda Ash aka Sal Soda.  This can be hard to find. It belongs in laundry aisles, and Arm & Hammer sells it (calling it Washing Soda), but few supermarkets actually bother to carry it, which annoys me to no end. You can also buy it wherever dye-stuff is sold. If you plan to use a lot of it, you could probably get it for cheap in large quantities from chemical suppliers.

3) Fabric detergent or liquid soap or dish soap. Beware of any additives in what you use, such as softeners or brighteners (in laundry detergent) or moisturizers (in liquid soap) which might leave residues on the fabric. Remember, you’re trying to strip the fabric clean. Use the simplest stuff you can find. I used our greywater-friendly Oasis detergent. It’s very basic. If I didn’t have that, I’d have turned to Bronner’s Sal Suds or dish soap.

How to:

How much water should you use? The fabric has to have lots of room. If you pack it into the pot it won’t clean properly.  Liles recommends 1 quart of water per ounce of cotton yarn and 2 quarts per ounce of cotton fabric.  This may mean you’ll have to scour in batches to do it properly. Allow time for this.

Recommended quantities of soap and soda vary somewhat from source to source. Personally, I don’t think the exact ratios are all that important. You’re using washing soda and detergent and heat to launder the living bejezus out of your fabric and there’s a lot of leeway in that.

That said:  For each gallon of water in your pot, add anywhere between 2 to 3 teaspoons of washing soda (3 teaspoons is a tablespoon) and 1 to 2 teaspoons of detergent. Again, that’s per gallon of water, not per pot.

Washing soda is somewhat caustic, so be careful when you use it. It won’t burn your skin off if some of the wash water splashes on your hands when you’re stirring, but it is harsh and drying. You’re supposed to wear gloves when working with it.

Add the fabric and turn on the heat. Bring the water to a simmer and keep it there for a minimum of two hours. Four hours would be better if you can swing it. Stir the fabric occassionally with a long wooden spoon to make sure it launders evenly. The water will turn this ghastly yellow brown color. It made me want to boil all of my laundry, old-skool style.

When you figure it’s ready or you’ve decided you don’t want to watch it anymore, rinse the fabric very thoroughly in cold water.

From this point you can go straight on to the dying process with the fabric wet, or you can dry it and store it.