From: Christina Z. Anderson (zphoto@montana.net)
Date: 04/19/03-11:42:35 AM Z
Thanks, Alberto,
But then why do we call a 30% solution mixing 300g in 1000 ml water?
Because it seems here Demachy is mixing 300g gum in 600ml water, correct?
Not taking into account weight but just matching grams to mls. But then of
course, the final amount of solution will be greater than 600ml because the
gum arabic will take up some space but not 300ml water space, so that's
where I get totally confused--you don't end up with 900ml of gum.
The other reason I get confused is Demachy recommends an 18-20 baume
solution, instead of the usual 14 that we recommend nowadays (I have
absolutely no clue what baume is or what a difference of 14-18 baume even
means to a layperson), and that Barnet also said he used a denser gum than
normal. But I think what you are saying is Demachy himself never changed
his own personal method of thick gum (saying, in one place, he used a 30%
and then in another to use 1 part gum to 2 parts water), but that he did use
thicker gum than others in his day seems to be a fact, according to Barnet
and possibly if I remember correctly, Wall.
So then tell me--if I mix 300g of gum in 1000ml can I call that a 30%
solution or am I mistaken?
Sorry if I seem dense...I am no scientist.
Chris
> Christina,
> I regret but I think so... it is about 30-35%!:
> 1 part + 2 parts = 3 parts; 1/3= 33.3%
>
> What is unclear in some recipes is what a "part" is: if it is a volume,
> surely 1 part of powdered gum arabic weights less than 1 part of water, so
> the resulting concentration will be below 30%.
>
> Alberto
>
>
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