[alt-photo] Re: casein

[Christina Anderson]

Alberto,

> 1) What is "3T dry"?

This is 3 tablespoons/about 30g dry powdered milk. However, it cannot be compared "apples to apples" with dry casein powder because it is mixed with an acid and water and precipitated out to a lesser weight.

When I weighed the final precipitate from this amount, it was about 27 grams. But that was wet weight.

Therefore, I was trying to calculate dry weight of it to compare it with dry weight of powdered caseinate. And dry weight was very close, within half a gram, of the protein content listed in the nutrition label on the package. Maybe just a coincidence.

It is easy to figure out percent solutions of caseinate powders in water, but not so easy, nor predictable to figure out percentage solutions when using skim milk or feta or cottage cheese. So I guess I can only compare wet curd recipes with wet curd recipes and dry caseinate powder with dry caseinate powder formulas.

Ultimately it seems the way it spreads is the ticket, and that will certainly vary with user preference.

Soon I will be using the red iron oxide you gave me last summer to calibrate a layer! So far just cadmium yellow, ultra blue, and cadmium red, because those are the three powdered pigments I have here aside from black.

I find there is hardly any if any flaking with the casein layer even when overpigmented to the point I have to cut back. But when I used the too thick casein it flaked. It sure holds a lot of pigment!

In the 1850s the varying strength of cow's milk was discussed, and city cows were called "cows with the iron tail" and that the milk was not as good as country cows. 

Wow, sure got sidetracked into a day of casein for some reason...

Chris



> 2) Searching for milk + casein + percentage (in Italian), I have found an article on "Variation in casein percentage in reference to content of somatic cells in milk of cows bred in district of Bari" where the authors write that the proteic fraction (total proteins) of milk is about 3.3%, that casein is precipitated at 20°C at pH 4.6 as calcium caseinate, and that 1 g of casein corresponds to 3 g of seasoned cheese.
> But the main goal of that article is to prove that in different seasons the cows produce milk with different amounts of casein and lactose (not mentioning the different milk -and hence cheese- produced by cows feeding on grassland or on hay, which I already knew). That is, milk is not ever the same. But I think that for printing purposes yes, the protein content of milk is a measure of casein yield. 
>> I am currently working with cottage cheese in red, yellow, blue, to determine amounts. Some of Enos' formulas are too liquidy for my tastes. I am finding that the cottage cheese diluted 120ml to 8 oz feels almost like a 14 baume gum, and mixed equally with pot di 10% and 1/4 teaspoon dry pigment, has a nice coating feel, not too thin, not too thick and grabby.
> 
> You can set up a personal measurement/comparison of viscosity by means of a pipette with two marks (upper and lower) and a chronometre. Aspire your liquid in the pipette above the upper mark, then grab your chronometre, let the liquid flow, and start the timing when the liquid is passing through the upper mark. Stop the chronometre when the liquid is flowing through the lower mark. Make this three times, then calculate the mean.
> I have done this, studying at home the fermentation of albumen, and the results are encouraging. One can compare these measurements against other liquids, e.g. different ratios of water and glycerine. 
> Alberto
> www.grupponamias.com
> www.alternativephotography.com/wp/photographers/rodolfo-namias-group 
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