[alt-photo] Re: evaporation of gum mixture

[Paul Viapiano]

Cool, thanks Katherine...

The Formulary gum is very light colored, and that's what I've used since day 
one. I got the DS gum on sale, great price and it is definitely a darker 
maple syrup color. Haven't used it yet...

p



----- Original Message ----- 
From: "Katharine Thayer" <kthayer at pacifier.com>
To: "The alternative photographic processes mailing list" 
<alt-photo-process-list at lists.altphotolist.org>
Sent: Friday, July 02, 2010 2:42 PM
Subject: [alt-photo] Re: evaporation of gum mixture


> Hmm, that's interesting.  I know nothing about what Formulary is  selling 
> for gum now, since I quit buying gum from them when they  switched from a 
> gum I really loved to a dark gummy gum for their  premium gum and 
> continued charging a premium price for it.  That was  some years back, and 
> as I said, I know nothing of their present gum.   The only gum I've seen 
> this happen with is Daniel Smith premium gum,  and it's been a continuing 
> problem with DS gum since I started using  it 3-4 years ago.  Exact same 
> containers  that I've always kept my  gum-pigment mix in, but with other 
> gums I've never had this  evaporation problem.  With the Daniel Smith gum 
> it's so pronounced  that  the mixes have become  more viscous within a 
> short time and  dried out altogether within a few months, so I've had to 
> throw out  the mixes, which is very annoying because it's extremely 
> wasteful of  pigment.  In the beginning,  I thought it was because the 
> workshop in  which I was doing gum  at the time  I switched to Daniel 
> Smith had a  bank of west-facing windows that didn't open, and it got very 
> hot in  there on summer afternoons.  But the problem continued unchanged 
> when  I moved to my present digs, where the gum workroom is in a cool 
> basement, so I'm convinced it's the gum (and besides, mixes made with 
> other gums and stored in the same containers survived that hot  workroom 
> quite well and remain  fresh and nicely pourable to this day).
>
> Whether you can reverse the problem by adding water is  a good  question; 
> in my case,  by the time I noticed the increased  viscosity, it was too 
> late; adding water usually wasn't a  satisfactory solution because the mix 
> had gotten gummier and the  water didn't mix in well.   But if you catch 
> it fast enough, as  you're doing by measuring the loss, it seems as if it 
> should work.
>
> Hope any of that is helpful,
> katharine
>
>
>
>
> On Jul 2, 2010, at 1:00 PM, Paul Viapiano wrote:
>
>> Formulary, til present.
>>
>> Then, will switch to DS.
>>
>> p
>>
>> ----- Original Message ----- From: "Katharine Thayer" 
>> <kthayer at pacifier.com>
>> To: "The alternative photographic processes mailing list" <alt- 
>> photo-process-list at lists.altphotolist.org>
>> Sent: Friday, July 02, 2010 12:54 PM
>> Subject: [alt-photo] Re: evaporation of gum mixture
>>
>>
>>
>>> Paul, what gum are you using?
>>>
>>>
>>> On Jul 2, 2010, at 11:51 AM, Paul Viapiano wrote:
>>>
>>>
>>>> Hello all...
>>>>
>>>> Having traced my pt/pd to a highly alkaline batch of Fabriano ,  I 
>>>> have another question on an entirely different subject.
>>>>
>>>> Sometimes I make these little premixtures of watercolor pigment  and 
>>>> gum arabic, nice and handy for printing tricolors in the  same 
>>>> pigments. I mix about 1 gram pigment to 9 ml of gum.
>>>>
>>>> In May, I made a mixture and weighed it at 17.9 grams in its   plastic 
>>>> snap-cap container. Two months later, it weighs in at  17.2  grams. 
>>>> What is it that is evaporating? Gum arabic? I'm  curious...
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