[alt-photo] Re: evaporation of gum mixture

[Katharine Thayer]

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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