Buckthorn berries, Yellow Experiment(s) 2

I tried to begin to follow another source to produce yellow.  I was working from Merrifield's Bolognese Manuscript, De Fiendis Viridibus again!  This book is so big, I'll never run out of possibilities. :D I will, ultimately, have to read it cover to cover.  I know I'm missing her details about general color production, opinions and her references.

Merrifield pg 428

The last ripe berries from Shana's New Hampshire Buckthorn bushes, about 30g, only yielded about 20 drops of juice so that attempt was unsuccessful.  At the end of September I found Buckthorn across the street in Saco.  I acquired the appropriate permission and went picking berries.  Someday I need to find an identification key for these Rhamnus spp bushes.  These berries seem plumper and larger, it must be a different variety or maybe they're just really ripe?

The 189g of big, juicy berries were manually squished with gloved hands and squeezed through cheesecloth to yield about 63g sludgy juice that I closed in a jar.

With fall archery events we were busy for more than the next month.  The juice sat closed in the jar for almost five weeks.  That was longer than the instructions indicated but I'm a volunteer... busy with being an archery safety officer and regular life activities when I'm not doing scribal or other Arts&Sciences projects!
I noted that when I finally opened the jar that the juice was definitely fermented and smelled like wine.
Athena Thickstun's blog helped me define that a 'fiasco' of wine is 2 liters.  One quarter of that would be 500g.  I didn't need that much so I made a smaller batch. Taking 200g distilled water I added a teaspoon of lye, K2CO3 (<1g on the kitchen scale that I had access to since I flooded the little one I had been using).  Then I added about the same quantity of alum (aluminum sulfate Al₂(SO₄)_3. which resulted in immediate fizzling.  [I have since found out that that is the wrong alum.  Next time I will use rock alum which I have learned is KAl(SO₄)₂.]  As instructed I heated it in my corning ware sauce pot on low for the time that it took me to recite the Our Father prayer in Latin:

Pater noster qui es in coelis sanctificetur nomen tuum.
Adveniat regnum tuum. Fiat voluntas tua sicut in coela et in terra.
Panem nostrum quotidianum da nobis hodie.
Et dimitte nobis debita nostra, sicut et nos demittimus debitoribus nostris.
Et ne nos inducas in temptationem.
Sed libera nos a malo.
Amen.

Adding the prepared lye/alum/water to the jar of juice there was an immediate color change of the reddish juice to a yellow/green liquid.

"Very fine white earth like the fellmongers use" is defined in Alexander's glossary in the Dover edition of Merrifield's treatises as lime.

In the spring of 2016 I was able to come back to this experiment.

I found pulverized (vs. pelletized) lime at one of the big box garden centers.

Speaking to Randy Asplund about it again he advised that I was basically making a lake pigment and elaborated on the volume of a mezetta, "In Florence the mezzetta was equal to 0.7613 liters."  I recalled that I had made a smaller volume and not very accurately measured the lye and water in the fall because my little scale had died the quick death of drowning in a different experiment.  Water under the bridge; I'll know the correct mezzetta volume next time!  Regardless, this might have worked anyway.

Back to creating a lake pigment... Cool!  I have never made a lake.  The Materials and Techniques of medieval painting talks about brazil lakes:

Sometimes the decoction of brazil wood with alum was precipitated with chalk, and a more opaque, pink, rose colour was produced by the resulting admixture of calcium sulphate to the alumina lake.  Sometimes, in England, instead of adding chalk to the solution, a chalk stone was hollowed out, and little holes were made in the bottom of the hollow, and the hot alum solution coloured with brazil was poured into the hollow of the chalk.  The reaction between the alum and the chalk took place at the surface of the chalk stone, in that case, and a crust of semi-opaque brazil lake was formed in the hollow and in the little holes.
When lakes were made by precipitating the alum solution with the chalk, the calcium sulphate was formed automatically along with the lake, in intimate combination with it.  Sometimes brazil lakes were given some opacity by adding opaque substances to them at the moment of precipitation, and even after.  When white lead was used, as it sometimes was, it had no other effect than to give a little substance to the lake, to make it a little less transparent, and to develop the rosy colour.  when marble dust and powdered egg shells were added to the newly formed lakes, or introduced along with the precipitating agent, they probably had the further effect of controlling the colour produced by reacting chemically with any excess of alum which might give a brown cast instead of the desired rose.  In all these cases the brazil colour was mordanted upon the white material, whether calcium sulphate, or an excess of chalk, or white lead, or marble dust, or powered egg shells.  The white substances were, so to speak, dyed with the brazil; and the pigment so formed was different from a mixture of a finished lake with the white pigment. (Thompson 119)

So, since I'm making a lake, I tried both crushed eggshell and pulverized lime.  I took about 10 g of each and pipetted off about 5 g of liquid from the jar into each material.  The eggshell is probably not pulverized enough to paint with.  I wonder if I can mull it or crush it down and use it anyway.  And just maybe add more of the buckthorn/aluminum sulfate/lye juice after "in order that it may become more beautiful and of a brighter colour" (Merrifield 428)

Buckthorn yellow.  Ripe buckthorn berry juice with lye and aluminum sulfate with crushed eggshell.

Buckthorn yellow.  Ripe buckthorn berry juice with lye and aluminum sulfate with pulverized lime.

This experiment produced beautiful yellows!  Some day I'll try to paint with them.  I bet you can paint with the plain juice like with the sap green as a transparent glaze.  I wonder if you can make a green lake with that juice with lime or eggshells too.  Anyway, yay yellow!

Mr. Asplund advises that this yellow lake can be produced in the same way from green berries too.  Awesome!