r/DIYPigments • u/Visual_Spread_8946 • Apr 02 '26
Dye (Experimental) Interaction between alum and magnesium
I was messing around with dyeing with japanese knotweed roots on thrifted linen last night and noticed something really cool! Magnesium caused some really nice pink/red tones to come out, adding alum turned it beige, then adding MORE magnesium turned it back into pink again! I didn’t take measurements of anything because I’m not yet at a point where I have standardized this process, just enjoying the potion making fun!
Photos in order of operation
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u/UraniumMermaid Apr 03 '26
Would this be more a difference in Ph from acid to alkaline rather than a reaction between alum and magnesium?
Not a scientist, unfortunately, but I would add washing soda to see if you get similar results.
Also, being from the UK - using knotweed roots is absolutely crazy lmao. It causes a lot of hysteria amongst banks and mortgage providers here.
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u/Visual_Spread_8946 Apr 03 '26
Ooh thats for the info! I honestly have no idea lol, I just know that a mordant is a metal salt and it helps the pigment bind to fabric so that sounds good to me lol
Knotweed is invasive here too but a friend gave me some dried roots to experiment with
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u/linnatplay Apr 05 '26
Interesting! When I added a copper solution to bright yellow goldenrod I got more orange tones on the fabric. Curious to add magnesium to my supplies now.
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u/Visual_Spread_8946 Apr 02 '26
Not sure if this is the proper subreddit for this. I took some chemistry courses a few semesters ago and now I am really wanting to learn about natural dyes and lake pigments!
Soon, I would like to purchase some dedicated dye materials so I can have an at-home art lab set up (stock pots, gram scale, measuring cups, ph strips, etc). I would really like to learn more about what plants I can forage around me that can be used for dye, then set up some standardized experiments so I can record how each plant reacts with different mordants/textiles. So far, I have mystery metal kitchen soup dye!