For silk I use acid dyes which give brilliant color. You can also use mx on silk but I think for the best color, acid dye is the way to go. The other day on the Complex Cloth list, the subject of color splitting came up. Color splitting is when you use a "mixed" color (as opposed to a pure color) for dyeing. The fabric will wind up with 2 or 3 colors. This has happened to me often but I never knew the scientific explanation behind it.Jane Dunnewold, a very talented artist explains that any mixed color (one that is not pure) can split and this process can happen with mx or acid dye. You can often tell when you open a jar of dye as you'll see specks of different colors throughout the dye powder. Each dye molecule within a certain color will react and strike at a different rate. This happens more readily when the fabric is bound with string, other resists, or is tightly wedged such as you see below. It should also be noted that splitting occurs in an immersion type situation, not low water immersion, printing or painting. It's also best to add the fixative at the beginning preventing the molecules from moving around which results in uneven dyeing. When I dye silk scarves, they are wedged into a stocking and tied on each end. They are put in an acid dye bath, adding the citric acid crystals in the beginning; I leave them in for @ 30 mins turning every 10 mins. I was so fascinated by color splitting and why it occurs, I went back and looked through my scarves to see which colors split. The samples on the right in each photo are the ones I made using a steamer - same color as the one on the left. The ones on the left were boiled in acid dye inside a stocking. I couldn't believe the difference. This is "Lobster Bisque". This next one is called "Pink Sand"...and one of my favorites.
Right now, I'm finding more of the lighter colors will split, but the jury is still out on that and to be determined when I've used more colors. This next one is "French Vanilla on left (boiled) and French Vanilla on right done in a steamer.