“First things first"
Fabric has to go through a few processes before it can be dyed with the natural dye. The 1st process is where the dye journey begins, and although this fabric without any colour might look like its ready to hit that dye pot is need this vital first process if you want to get good results.
Scouring: to clean or brighten the surface of (something) by rubbing it hard, typically with an abrasive or detergent.
Protein fibers: Should be scoured with a PH neutral soap. I like to use a fair trade Pure Castile Liquid Soap. Firstly you will need to weigh your wool or silk and make a note of this this is your WOF (weight of fabric). You will need 1 teaspoon per .5kg of fabric Put the fabric in a large stainless steel pot so there is room for the fabric to move about. if you crowd the fabric it won't scour properly and will affect your dye results. Fill with water so the fabric is well covered and heat to about 60oC for about 1 hour. Don't agitate the fabric too much as wool can felt and silk can damage. Let the fabric cool down and rinse well.
Cellulose fibers: Can be scoured with a PH neutral soap and Soda Ash* . Weigh your fabric and make a note of the WOF. You will want 3 tablespoons of soda ash per 1kg of fabric. Make sure that all of the soda ash has dissolved into the water and add 4 teaspoons of PH neural soap. Make sure there is enough water in the pot to allow the fabric to move freely. Bring to a boil and simmer for 1 hr then allow to cool. Rise the fabric well to remove the soap. If you are not moving onto the next process straight way then allow your fabric to dry and store in a cool dark place.
Its so easy to just want to jump to the dying process but this is a must do step and you will defiantly see the benefits in properly scouring your fabric.
Remember to label your fabric! I like to label mine with a tag that tells me the WOF (weight of the dry fabric) date of scouring and the type of fabric, ie: organic cotton, canvas cotton. And where I brought the fabric from.
Soda Ash* - Make sure that you use 100% pure soda ash (sodium carbonate Na2CO3) , this can be confused with washing soda, as washing soda can contain whiteners that can affect the dye process later on.