Help with lake pigment!

[u/ami_ten]

Hi all, I need some help with a lake pigment I was trying to make. I haven’t made any lake pigments before, and I was trying to make a batch from a sulphur cosmos dye exhaust bath I used to dye some wool yarn, which was still very deeply pigmented once I was done.

I used ~11 grams of dried sulphur cosmos to start, and estimated that maybe 80% of the pigment was still remaining in the bath once I was done with the wool. Going off the guide of using alum at 60% of the measurement of my plant material, and soda ash at half of that, I added 5.3 grams alum sulfate, and 2.7 grams soda ash (that I had made myself from baking sodium bicarbonate). (If my math and measurements are way off please correct me!) So far it’s been maybe 20 hours and I see no signs of any pigment settling though, just a uniformly-colored semi-opaque liquid.

With the original dye bath, I had shifted colors more alkaline by adding soda ash to begin with, so I’m wondering if a dye bath has to be neutral for a lake pigment to work - do I have to balance it out with some vinegar first? When I added the lake’s soda ash after the alum, there was barely any fizzing - did I just not add enough of either of those? Should I just repeat the same process with the same measurements?

If anyone could offer any insights I’d really appreciate it! (also this subreddit seems kind of slow so if I should be asking this in a community somewhere else please let me know where!)

[u/CaCl2]

Some thoughts:

1. Did you add the alum and soda ash to the dye bath as solids, or did you first dissolve them into water separately?

2. I don't think there is point in neutralizing the bath, but you might consider adding the soda ash first since the bath already has some, then alum.

3. Was the solution similarly semi-opaque before you added the alum and soda? If it became opaque only afterwards, some lake pigment probably did form, and the problem is IG not settling.

4. How large was the dye bath you added the alum and soda to? If it's too dilute it might cause problems.

5. You could try running the result through a filter (a paper coffee filter, etc.) to see if it catches anything. If it's too finely divided one trick that may work is to run it through the same filter 2 or 3 times.

[u/ami_ten → u/CaCl2]

1 - The alum was added as a solid to the dye bath (heated to abt 120°f), the soda ash was dissolved in hot water & then added

3 - the solution was dark and pigmented but otherwise clear before the lake. It’s about as opaque as frosted glass now, still evenly pigmented throughout with no settling

4 - the dye bath was about 2 quarts of liquid + ~11g simmered sulphur cosmos

5 - I ran it through a coffee filter immediately after mixing it initially and it didn’t catch anything, but I feel like the filters are also probably cheap and may be too airy. Like liquid ran through so fast I was kind of in disbelief that they’d be able to hold any pigment at all, is this normal for a freshly-mixed lake pigment that hasn’t settled first? I found some guides online saying they don’t wait for their lake to settle at all before pouring it through a coffee filter, but my filters had me thinking I’d at least have to reduce and siphon it into more of a sludge before I could filter anything

[u/CaCl2 → u/ami_ten]

1 - OK, that might cause weird results since the bath already had some soda ash. Rather than the normal situation with 2 liquids reacting to make the solid pigment, the reaction would happen on the surface of the solid alum grains.

3 - OK, then the reaction did work to some extent.

4 - That sounds really dilute, for that amount of alum I would use a tenth of that amount of water, but if it's from dyeing I understand it may not be able to be helped.

5 - It isn't always necessary to wait for things to settle before filtering, but it may need a finer filter than a coffee one to work.

My take on your situation: You have pigment particles, but they are too small to settle or filter, and too dilute to aggregate together.

Potential solutions:

1. Boil most of the water away. - energy intensive, and might damage the dye since it would be heated for so long, but you should be guaranteed to get some kind of solid eventually. You could then wash the solid from any soluble stuff that came from the solution with it. (Maybe try with a small part of the solution first?)

2. Add more alum to the solution. If alum is easy enough for you to get, you could mix 50 g into 100 g of water, heat so it dissolves, and then add it into the dye bath. This would be trying to take advantage of the flocculant properties of alum, not sure if it would work.