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The PH of Logwood Extract

The PH of Logwood Extract

I guess i was one of those people that put Logwood extract in a pot with tap water and everything always worked so i never thought about process that much. After reading some post from fellow dyers that were using Logwood extract purchased from my shop i got a little more curious about the process. Some of the students in this recent class were getting light grey or what i would call grey lavender while others were getting more purples. After ruling out things like high temperatures(above 180) and various modifiers like iron, I began to focus on the water in the dye bath.

Through some research and further reading i discovered that Logwood is very sensitive to so several things. An interesting peice of information that i came across was that Logwood was actually used at one time for determining PH. Logwood placed in an alkaline solution will turn violet/purple, placed in neutral water it turns brown and placed in acidic water it turns yellow. So you can see where im headed here, i think grey and grey lavender is all PH related.

Here is an explanation of each piece in the image.

  • Image 1:
    • Mordant with potassium alum at 15% in a bath of hot water from the sink for 30 minutes.
    • Dye bath is 1% logwood extract in regular tap water with citric acid to lower the PH to around 3.
    • Dye bath heated to 170 deg for 45 minutes.
    • The photo does not do justice to the gold color. It is REALLY rich. I love the color but you can see what an acidic dye bath does to the logwood.
  • Image 2:
    • Mordant with potassium alum at 15% in a bath of hot water from the sink for 30 minutes.
    • Dye bath is 1% logwood extract in regular tap water. PH approximately 7
    • Although the photo looks a little grey, it is defiantly light purple in real life. Back to that grey lavender thing.
  • Image 3
    • Mordant with potassium alum at 15% in a bath of hot water of tap water for 45 minutes in a pot heated to 170 deg
    • The dye pot is DISTILLED water and i increased the logwood just a little. Remember that these scarf's weight only 14 grams so doubling the logwood was only going from 0.2 grams to 0.4 grams. Not a lot of logwood either way.
    • The logwood struck almost immediately and when it came out of the pot it looked black. Again, the photo doesnt do justice, the scarf is a dark purple, almost maroon.
  • Image 4
    • Mordant at 15% with potassium Alum in a heated bath with tap water at 170 deg for 45 minutes.
    • Dye bath was 1% logwood extract and dye water is DISTILLED water with 1 tbs baking soda added to 1 gallon of water. The sample was heated to 170 deg for 45 minutes.
    • A very nice purple i think.

I had a couple more samples that were COMPLETE fails and they both had only one thing in common.........SOADA ASH. Apparently logwood does NOT like soda ash. Both samples looked like they had been dipped in weak tea. I actually scoured the scarves and tried to over dye them and got nothing so im making a mental note to put the logwood dye and the soda ash in different rooms(lol). use baking soda to adjust your PH. Its easy and cheap.

In the next part, i will determine what the difference in tap water and distilled water is with a couple more experiments to determine if the color difference is more sensitive to the water or the PH. Im still leaning toward the PH answer.

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Ruth - April 3, 2021

What happened to the pics? BTW, I’m loving your products.

Wendy Mahon - May 10, 2020

Could you tell me what is the ph of Image 3 and 4?

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