[Alt-photo] Re: lump gum

[Laura V]

Thanks for this. I have not used a preservative before (mainly because I 
don't know where to buy it). I usually just mixed a small batch (when I 
had the powdered stuff) and kept it in the fridge and used it within 2 
weeks.

Unless, is glyoxol a preservative? I have some that I used in paper 
sizing. It would be handier to always have the gum pre-mixed.

Laura

On 10/19/13 3:01 PM, Guido Ceuppens wrote:
> Laura,
>
> I used the following procedure with lumps of gum:
>
> 300 grs of gum are slowly dissolved in 850 ml of cold water, this may take
> several days. The impurities are then filtered or fished out, some
> recommend to suspend the lumps of gum in a muslin bag to prevent the
> impurities to float in the solution. Once dissolved a preservation agent
> must be added to the solution: in the past I have added either 15 ml of
> formol or 7.5 grs of sodium benzoate. I have used the thus prepared gum for
> years without it going bad (I mainly use casein now but occasionally use
> gum that was prepared from powder –same procedure- 7 years ago).
>
> Welcome back and good luck,
>
> Guido
>
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