Lake pigments

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ResolvableOwl

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Warining: Rabbit hole!

(lye-based, because you will need some alkali to precipitate the alumina, that's the whole point of lake pigments)

Right now, things are about to escalate once again, the topic this time are lake pigments. Lakes are an age-old technique to convert soluble, organic dyes into insoluble pigments. It is interesting for soapmaking, because many organic dyes are prone to migration, and diffuse through soap over time, blurring sharp boundaries, e. g. within swirls or embeds. Sometimes this is intended, but sometimes you might want to avoid it.

The general principle is that a water-soluble dyestuff is mixed with a solution of an aluminium salt, and then the aluminium is knocked out of solution to form insoluble aluminium hydroxide, carrying the dye with it into a fine flaky powder, that can be dried and used as a pigment. When carried out with wastewater treatment in mind, it is called flocculation, fabric dyers will recognise close relation to the se of mordants.
Literature sometimes also mentions salts of iron, copper, lead or other metals. But I will focus on aluminium because it is one of the, say, less troublesome cations in soap (doesn't proliferate DOS).

The most usually used aluminium salt is alum (potassium aluminium sulfate). Other soluble Al salts will work too. I myself will use aluminium formiate because it is what I have at hand (originally as a textile mordant).


In practice, there are two approaches to end up with flocculated dye:
  1. the alkali-alum route, where first an alkaline solution of the dye is made, second the alum is added.
  2. the alum-alkali route, where the dye is prepared in an (acidic) alum solution, that then is made alkaline to form the insoluble final product.
This presentation describes both processes with quite some detail, from the analytical eyes of fine art archaeology.
The online DIY community appears to prefer the alum-alkali process. It's a great way to salvage the remaining colourants in spent dye baths from the drain!


I've posted some success with safflower petals already a few days ago. But foreseeing it will be buried there rather sooner than later, I'll start a new, colourful thread here.
My short-term goal is still the same: fill that awkward red-orange-yellow rainbow gap between alizarin/madder pink and chromium oxide green with soap-fast, non-bleeding, bright and reasonably non-toxic colourants.
 

ResolvableOwl

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Safflower – THE GIRAFFE
safflower.jpg

1 g safflower petals + 40 mL water, soaked overnight, then boiled up in the microwave. Alum-alkali precipitation route. At all dilutions but these dried lake flakes, the pigment has a bright, warm yellow colour.

Turmeric extract – THE PAPER LANTERN
turmeric.jpg

#Turmeric spice powder, when cold extracted with weak lye solution, turns bright scarlet.
I first dissolved aluminium formate in water and added dilute KOH (first turns turbid, then clear again). Then I added turmeric powder. After a few minutes of extraction, I then filtered off the insoluble parts of the rhizom powder, and obtained a clear solution with a bright, neutral red colour.

Then, I cautiously acidified (alkali-alum route) and the solution turned opaque.
As acids, I tried sodium bicarbonate and very dilute vinegar. Both do work; the bicarbonate stayed red initially, with the vinegar it changed more into orange. Both took on a similar blood orange colour upon sedimentation. I combined them, washed, and eventually filtered off this lake pigment.

These crazy craquelé patterns form all by themselves when the lake is drying up (I placed it on the radiator over night).
 
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ResolvableOwl

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Not sure about chlorophyll, it's lipophilic (oil-soluble), likewise anything carotenoid (carrots, tomato, red palm, annatto, astaxanthin…). It makes extraction into water very difficult, and I'm not sure if the lake process would help against bleeding in soap.

Anthocyanins, however, sound like a fun thing to do & try out. Hibiscus, butterfly pea, red cabbage, elderberry and aronia come to my mind. Guess it's time for a bit of research first, to estimate which is easiest to work with and likely to be successful. I have not the faintest idea if the lake precipitation can do anything about the disappointing lye fastness – but that is what makes it fun and worth trying!
 
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Ok, I have four small trials going - turmeric, butterfly pea powder, blue spirulina, and pitaya powder. I am really flying by the seat of my pants but I’m reading websites and guidance. My local Walmart had alum, and I’m using washing soda for the alkali. I made solutions with each, strained them with paint strainers, added alum (dissolved in water) then added washing soda (dissolved in water) to get the ph to 7. Then I let them settle and tried to pour off the liquid. I’ve added more water and will let them settle overnight. I could only find the stem of my turkey baster (no bulb) so it’s a little tricky. Maybe I’ll go get one tomorrow.
By the way I can’t open that pdf, it just shows the front page. I tried googling the title but couldn’t find it.
Updates to follow.
 
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ResolvableOwl

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Great timing 😬 Let's hope that you have more luck with…

Spirulina (Phycocyanin) – THE PRETTY FAILURE
spirulina.jpg
I first extracted whole (green) spirulina with plain water to get out the phycocyanin (blue) by a first filtration, which works great. When adding the alum, it immediately turned murky (azure blue precipitate) which wasn't supposed to happen until adding the alkali … I proceeded anyway:
spirulina_precipitate.jpg
I was still optimistic at this point. But it turned out that the phycocyanin just did not stick at all to the aluminium hydroxide, and mostly just rushed through the filter. The little that did get caught, is most likely not strongly bound nor protected from lye. Even if it were, phycocyanin is still among the least lightfast pigments I know of.

It'll get its chance to prove me wrong, though. But in the end, I won't be sad if it does not work out. I'm happy with ultramarines and/or indigo for these hues.
 
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Great timing 😬 Let's hope that you have more luck with…

Spirulina (Phycocyanin) – THE PRETTY FAILURE
View attachment 63912
I first extracted whole (green) spirulina with plain water to get out the phycocyanin (blue) by a first filtration, which works great. When adding the alum, it immediately turned murky (azure blue precipitate) which wasn't supposed to happen until adding the alkali … I proceeded anyway:
View attachment 63913
I was still optimistic at this point. But it turned out that the phycocyanin just did not stick at all to the aluminium hydroxide, and mostly just rushed through the filter. The little that did get caught, is most likely not strongly bound nor protected from lye. Even if it were, phycocyanin is still among the least lightfast pigments I know of.

It'll get its chance to prove me wrong, though. But in the end, I won't be sad if it does not work out. I'm happy with ultramarines and/or indigo for these hues.
Ha - mine doesn’t seem to be binding at all either. So far I would say that the best is turmeric, followed by butterfly pea, followed by pitaya, with blue spirulina (phycocyanin) in last place.
 

ResolvableOwl

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That pitaya is a lovely pink!
Hrm. The butterfly pea is really weird. I got a similar camouflage-olive colour, upon kneading butterfly pea powder directly into soap dough, as it happened to Nada Makes with red cabbage. It seems that these anthocyanins are really quite finicky fellows.

What I noticed about all of your lakes is that they have a whitish rim around the filtrate in the filter. If I had to guess, I'd say you use a lot (possibly a lot too much?) alum. And/or I use too little. It might or might not matter at all, I'm just wondering. What are your typical ratios between dyestuff and alum? For the safflower, I have used 0.5 g aluminium formate (0.8 g alum equivalent) for 1 g of safflower petals.



My programme:
Currently in the making: black tea, yerba mate (not aiming for chlorophyll, but chlorogenic green)
Plans for: rooibos, onion skin, camomile, elderberry
Outlooks of the would-have-to-order-dyestuff-first-but-sounds-interesting type: dyers's rocket (reseda luteola), agrimony?
ETA: Guess whose lilac shrub will have to lose some twigs soon…

I need to get my hands on some alum.
You have got some of it. Just for the record/for someone without a source/in a hurry: it should be fine (at least for the alkali-alum process) to just dissolve aluminium foil in weak NaOH.
 
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That pitaya is a lovely pink!
Hrm. The butterfly pea is really weird. I got a similar camouflage-olive colour, upon kneading butterfly pea powder directly into soap dough, as it happened to Nada Makes with red cabbage. It seems that these anthocyanins are really quite finicky fellows.

What I noticed about all of your lakes is that they have a whitish rim around the filtrate in the filter. If I had to guess, I'd say you use a lot (possibly a lot too much?) alum. And/or I use too little. It might or might not matter at all, I'm just wondering. What are your typical ratios between dyestuff and alum? For the safflower, I have used 0.5 g aluminium formate (0.8 g alum equivalent) for 1 g of safflower petals.



My programme:
Currently in the making: black tea, yerba mate (not aiming for chlorophyll, but chlorogenic green)
Plans for: rooibos, onion skin, camomile, elderberry
Outlooks of the would-have-to-order-dyestuff-first-but-sounds-interesting type: dyers's rocket (reseda luteola), agrimony?
ETA: Guess whose lilac shrub will have to lose some twigs soon…


You have got some of it. Just for the record/for someone without a source/in a hurry: it should be fine (at least for the alkali-alum process) to just dissolve aluminium foil in weak NaOH.
I know I saw that white rim too. I’m hoping it’s just on the rim and won’t affect the lake. The ratios I used were 5 g organic matter in 100 g water, and added 10 g alum in 100 g water. Actually - I think I added half of that to each one. Shoot. I didn’t keep good track. ALeo there was probably double that amount of butterfly pea powder. Then I added washing soda to get it to ph 7.
More updates to follow.
 
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ResolvableOwl

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I myself will go on testing these with a balanced soap dough (i. e. with a slightly positive superfat). Back then, I did the lye-heavy shenanigans just to be able to use the same dough also for oily additives, but this is not needed here. My reasoning for using soap dough is exactly that it has no excess lye that might be harsh to sensitive colourants – or the lake itself! Aluminium hydroxide dissolves in strong lye, so it would be pointless to use them in CP or anywhere near free alkali.

Do whatever you want to do with them! Knead them in soap dough to challenge their stability in the slightly alkaline environment of saponified soap. You can stir them into molten M&P soap. Mix them with flaxseed/walnut/safflower oil to make oil paint. With gum arabic for watercolour paint. With heavy cream or egg yolk for tempera. With wax for encaustic. Or rub them directly onto/into rough paper.
 
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I myself will go on testing these with a balanced soap dough (i. e. with a slightly positive superfat). Back then, I did the lye-heavy shenanigans just to be able to use the same dough also for oily additives, but this is not needed here. My reasoning for using soap dough is exactly that it has no excess lye that might be harsh to sensitive colourants – or the lake itself! Aluminium hydroxide dissolves in strong lye, so it would be pointless to use them in CP or anywhere near free alkali.

Do whatever you want to do with them! Knead them in soap dough to challenge their stability in the slightly alkaline environment of saponified soap. You can stir them into molten M&P soap. Mix them with flaxseed/walnut/safflower oil to make oil paint. With gum arabic for watercolour paint. With heavy cream or egg yolk for tempera. With wax for encaustic. Or rub them directly onto/into rough paper.
Perfect. Thanks.
 

ResolvableOwl

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This is actually a bit of a tangent, since there is not exactly a shortage of brown soap colourants…

Black Tea – BEAR WITH ME
black_tea+bear.jpg

Alkali-alum route (dissolved the aluminium salt in weak KOH before adding to a terribly oversteeped black tea; lake precipitation by vinegar addition until down to pH around 7). I couldn't resist, ground some of it (mortar/pestle), and mixed it with HL safflower oil into a deep translucent oil paint, with a happy, chocolate (or bear?) brown colour.
 

ResolvableOwl

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Yerba Mate: BRONZE MEDAL
mate.jpg
Doubtlessly my darkest lake pigment so far (What was my original idea? Rainbow?). Usually I'm annoyed with the bright, deep green stains that drops of mate (and if it's only from cleaning the gourd after use) leave everywhere. Ironically, while yerba mate is foliage that is green because of chlorophyll, this is another green. Not unlike coffee and sunflower kernels, it is a good source of chlorogenic acid, that turns turquoise-green when combined with alkali, protein/ammonia, and oxygen/air. Plus, chlorogenic acid is a polyphenol, i. e. should be straightforward to turn into a lake pigment (unlike chlorophyll).
So, several days ago I soaked some yerba mate in water, added a few drops of NaOH, and a few crumbs of ammonium chloride (stinky, it starts releasing ammonia), and let it stand open. It quickly turned from the known olive-brownish colour dark brown, then black. Really black. Think of ink (slight tangent – if iron weren't notorious for promoting DOS, ferric salts would make a fantastic mordant for black pigments from tannin-rich infusions like oak galls or black/green tea).
Anyway. Yesterday the ammonia smell was gone, and I obviously went for the alkali-alum route: precipitating aluminium hydroxide from alkaline solution with vinegar. The sediment was very dark and there was also a lot of it. I guess that this is a much more intense dark pigment (hue like burnt umber?) than the black tea. I have no immediate use for it. I will however try out another alkaline extraction but somehow try to be quicker than the oxidation, and/or give the acidic alum-alkali route a try. Somehow I am convinced that it is possible to squeeze hues from yerba mate that are very different to this.
 

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The project described only dyeing with goldenrod, I didn't find anything about its smell?
 

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