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[chiaroscuro_violins]

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[Deo Lawson]

It will probably keep for your great grandchildren if you put it somewhere dark, cool, and without a draft.

[MikeC]

lake would last probably.  Roots could be bagged and stored in a freezer maybe

[chiaroscuro_violins]

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[Deo Lawson]

Both

50 minutes ago, chiaroscuro_violins said:

The powdered lake, or the dry roots?  

Both. Raw root would have to be bone-dry.

[Davide Sora]

8 hours ago, chiaroscuro_violins said:

The powdered lake, or the dry roots?  

I have thirty year old madder root which still works fine for making pigment. The pigments also last over time, even if the color undergoes some variation it does not fade much if at all (at least this is my impression). The one fixed on the iron sulfate (brown) gets darker over time, mine have turned almost black which is a good thing for me

[Andreas Preuss]

I suppose it is just like wood. As long as you keep it dry and out of direct sunlight it can be stored for a long time.

[Michael_Molnar]

On 11/2/2021 at 7:03 AM, Davide Sora said:

I have thirty year old madder root which still works fine for making pigment. The pigments also last over time, even if the color undergoes some variation it does not fade much if at all (at least this is my impression). The one fixed on the iron sulfate (brown) gets darker over time, mine have turned almost black which is a good thing for me

This reinforces my distrust of iron (in salts) that can switch valence and become black. It depends on the pH of the medium, I presume. I defer to the chemists, nevertheless.

[Michael Darnton]

I have a jug of madder that has been sitting in lye water, extracting, for 25 years. When I used it last, it was still fine.

In natural madder colors there are a few different colorants and the brighter are more unstable, fading through time, inevitably.

[Michael_Molnar]

3 hours ago, Michael Darnton said:

I have a jug of madder that has been sitting in lye water, extracting, for 25 years. When I used it last, it was still fine.

In natural madder colors there are a few different colorants and the brighter are more unstable, fading through time, inevitably.

Right. Alizarin (PR 83) in madder is probably the most stable of natural organic pigments.

[JacksonMaberry]

Yeah dry them well and you should be in good shape! Bedstraw is a little more work than dyers madder (Rubia tinctorum) in that it produces less anthraquinone than it's more popular cousin, but still viable as you have said. Iirc the proportions of the anthraquinones are a little different as well (less purpurin to alizarin I think? Makes for a slightly less complex color, but I don't think it's a big deal). When you make your lakes, make sure to have a good variety of metal salts on hand. Alum is the most used and gives a good clear red, but tin is useful if you want to get oranges. YMMV with iron salts (ferric Chloride would be my recommendation rather than the ferrous salts of sulfate or chloride). Most lakes precipitated with iron salts are one shade of brown or another and thereby, due to the iron oxide's dominance, will tend to run together. Manganese salts can be useful, too. I'd say at least make sure you have aluminum sulfate, zinc sulfate, stannous sulfate or chloride, and manganese sulfate. 

If possible, try to at least get a ballpark for the molar concentration of Alizarin in your dyebath so that you can use the right amount of salt for the reaction. Especially valuable with tin salts, which are much more expensive than the others. Either that or use too much and plan to recrystallize the tin salt or you're pouring money down the drain.

[chiaroscuro_violins]

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[JacksonMaberry]

56 minutes ago, chiaroscuro_violins said:

I like using bedstraw because I can just go out my front door and pull it up from the ditches.  Madder doesn't grow around here.  I've only used Alum in the past, but I have enough roots now to try various different salts.  

That's great! I am very much in favor of using regionally available materials! Just figured I'd share what I know of the relevant chemistry. Cheers! Show us your lakes when you get around to it! Try rosinates with it, too, if you like. They can be used as a varnish resin or ground into another varnish just like a lake but with better transparency/intensity gram for gram.

[Davide Sora]

On 11/2/2021 at 12:03 PM, Davide Sora said:

 The one fixed on the iron sulfate (brown) gets darker over time, mine have turned almost black which is a good thing for me

 

On 11/3/2021 at 1:24 PM, Michael_Molnar said:

This reinforces my distrust of iron (in salts) that can switch valence and become black. It depends on the pH of the medium, I presume. I defer to the chemists, nevertheless.

Hi Michael,

I think your observation is correct, what I meant by saying that it is a good thing that my madder pigment fixed on iron sulfate has become almost black, it's that I am referring to the powdered pigment stored in the jar, not in the varnish.

I suppose this could mean that the transformation into iron III has already occurred and therefore at this point it should be stable, and used in the varnish it has a similar effect to other blacks such as carbon black for example, but with a better transparency and an interesting green hue when very diluted.