[alt-photo] Re: casein

[Christina Anderson]

OK, let's make this clearer then because it is wrong below.

Cottage cheese in America is bought by weight in ounces--an 8 oz. container. Wish I could change that, but I can't :)

It says on the container "226g."

I rinsed the liquid off these curds and came up with 140g remaining curds WET.

In this container there is said to be 28g protein but it does not specify what kind of protein

I mixed 50 ml of 10% ammonia with 70 ml of plain water into this amount to come up with a very nice thickness of casein for my purposes. I first added teh 50ml of 10% ammonia and the curds immedately started to turn clear. After a very short while the entire amount was liquified (an hour or so?). I tried to print with this and it was too thick. 

I poured 70ml water into the container, bit by bit, to see about when it "felt" right, and settled on 70ml total water. Then some drops of thymol to preserve. I printed with this immediately.

In relation to your and Peter's 23% figure of dry casein from skim milk: I use 3 Tablespoons/30g of powder per cup of skim milk from dry powdered milk. I ended up with a curd the size of a large walnut that weighed 37g wet. I dried that and weighed and there is no way that it even approximated 23g dry but maybe I am reading your notes wrong. It was very close to 9g dry. I have no idea why this discrepancy but it is possible in the vinegar steps of the process that some of the casein went down the drain and that I dried the curds to a crisp or something. But wet weight of the walnut sized curd was

Chris



Christina Z. Anderson
christinaZanderson.com

On Jun 15, 2012, at 7:26 AM, Alberto Novo wrote:

> Chris, 
>> 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.
> 
> I like these unit conversion problems!!!
> Why are you starting with ml and ending with oz?
> Let me know if I am reading correctly:
> You took 120 ml of cottage cheese and added ammonia up to 8 oz.
> 8 oz = 236 ml, so that you diluted about 1:1 your cottage cheese.
> Diluting 1:1 this with dichromate = 473 ml.
> 1/4 teaspoon = 1.23 ml, but to convert this into grams one needs the bulk density of the pigment. This may vary with the nature of the pigment
> I have found:
> lamp black 100-200 kg/m3 (0.1-0.2 kg/L, g/cc)
> raw Sienna 0.6 kg/L
> black iron oxide (Mars black) 1 kg/L
> burnt Umber 0.7 kg/L
> quinacridone red 0.39 g/cc
> phthalocyanine blue: 0.45-0.50 g/cc 
> Generally speaking, earths and oxides have a bulk density more or less twice that of organic pigments. 
> So, your 1.23 ml may be from 0.5 to 1.2 g depending on the pigment, and it is about 1.25 to 3%, or 0.0125 to 0.03 g/cc in the casein solution. 
> When I printed my caseins with red earth, I used:
> 0.8 g casein + 6.5 ml 15% ammonia + 3.5 ml water: this is about 8% casein w/v.
> Then I added 0.4 g of red earth for 1 cc of 8% casein solution, plus an equal amount of 15% am dichromate. This solution has to be prepared at the moment of use (metal oxides, as you know, react with casein).
> This is about ten times the concentration of natural pigment / 14 Be gum arabic I use (for earths) without flaking. 
> Alberto
> www.grupponamias.com
> www.alternativephotography.com/wp/photographers/rodolfo-namias-group
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