Dyeing Basics: The Science of Dyeing Wool for Rug Hooking

April 8, 2009 3 comments | Updated March 12, 2018

Written by Cindi Gay

I will have the dye pots out for the month of April. This is when I prepare for all the workshops I will be teaching the rest of the year. It’s not a perfect process and I will usually have to get them out again throughout the year, but only for specific jobs. Here are my thoughts on the Basics of Dyeing Wool for Rug Hooking.

There are many, many procedures to get dye into wool. There are three main things that you must provide:

  1. Time
  2. Temperature
  3. Acid


Time is very important. I’ve called customer support at PRO Chemical more than once to ask, “How long?” I’ve gotten different answers at different times. Some rug hooking teachers teach that when the dye is absorbed or when the water is clear, the dyeing is complete.  Some recommend as I do that you need to cook it at least 30 minutes, regardless of when the water clears.  Others teach that you cook for 30 minutes AND leave it overnight in the warm water.  So I decided to do a test.

I dyed 3 pieces of wool the same size in the same pot.  I used blue because blue is the first color to fade.  As soon as the water was clear, I removed one piece.  I cooked for 30 minutes and removed the second piece.  Then I let the pot sit overnight.  I then washed and dried all three pieces.

I separated each piece into three pieces.  One set went into my underwear drawer inside my dark closet.  A second set was hung in the studio in plain view, but not in direct light.  The third was taped to a south facing window.

At the end of several months, the ones in my underwear drawer were unaffected.  The pieces that were pulled out as soon as the dye cleared were more faded than the others.  The ones I cooked for 30 minutes and the ones I left overnight showed some fading when left in direct sunlight but they fared about equally.

I cannot show you pictures of the results.  I need to repeat the test because my puppy ate the results.  Jackson is beyond most of his teething, but suddenly, he is chewing up everything.  How can you get mad at this face?

So innocent


I begin my 30 minutes from the time the water comes to the near boiling temperature or whenever I add the acid, whichever comes last.  My largest pots take over an hour to get up to speed.

As a general rule of thumb, if the dye is not clearing, raise the temperature and/or add acid.

The heat source can be anything.

  • stove top burner
  • oven
  • pot over a camp fire
  • slow cooker (takes way too much time for me)
  • electric fry pan

There are many others but you get the point. One source I do not use is the microwave. The microwave excites the molecules in the wool to heat it. I am not sure how this affects the wool. I like more traditional methods best.


White vinegar or Citric Acid crystals are used to change the pH value of the water. The bigger the pot, the more acid you must add. I prefer Citric Acid crystals. They are smaller and easier to store. One 5 lb. bag of citric acid is the equivalent of 9 gallons of vinegar. Think about a 5 lb. bag of sugar. This is much easier to store than 9 gallons of vinegar.

One problem I have with dyeing is that my sinuses get “burned” by the acid steam. I have very sensitive sinuses and several allergies. After several pots of dyeing, I end up with dry sinuses and a sore throat. It goes away when the dye pots do but it is more severe when I use vinegar.

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Dyeing Rug Hooking Wool is Messy

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