[alt-photo] Re: evaporation of gum mixture
Katharine Thayer
kthayer at pacifier.com
Sat Jul 3 01:18:21 GMT 2010
Okay, that sounds like the standard DS gum, not the premium; I have
no experience with that.
On Jul 2, 2010, at 5:05 PM, Paul Viapiano wrote:
> 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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>>>>>
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