[alt-photo] Re: IDEA? NEW ALT PHOTO BOOK

[Paul Viapiano]

Thanks, Katherine...

If the list had a sticky for posts, this would be at the top.

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, April 23, 2010 11:08 AM
Subject: [alt-photo] Re: IDEA? NEW ALT PHOTO BOOK


> Whatever size is used,  the gum attaches to the paper fibers rather  than 
> to the size, so the material used in the size shouldn't make any 
> difference to how the gum adheres to the paper.   Difficulties with  size 
> arise when the size becomes so thick or heavy that it clogs the  surface 
> fibers and leaves nothing for the gum to hang onto; then the  hardened gum 
> tends to slide off into the water.  This is true  whatever size is used, 
> and this is why the optimal dilution of PVA  size is different for 
> different papers, because different papers have  different surface 
> qualities, and the size needs to be diluted enough  that it soaks into the 
> paper leaving surface fibers ("tooth") open  for the gum to attach to.  So 
> no, the gum doesn't "sit" on top of PVA  size any more than it does on top 
> of a gelatin size.
>
> Paul: Since the unreacted dichromate and soluble gum wash off in 
> development, there are no reaction products left in the finished and 
> dried print, so there would be no purpose in exposing the dried layer  to 
> UV.
> IME, a print that's properly exposed and developed is entirely stable  to 
> rewetting.  If soluble gum is left in the print, in other words if  the 
> print is removed and dried while there is still soluble gum in  the paper, 
> then that soluble gum will continue to dissolve and change  the print when 
> it is rewetted, but if the print is properly exposed  and developed, there 
> will be no undissolved gum and the print will be  entirely stable to 
> water, containting only hardened (insoluble) gum.   If you think about it, 
> the permanence of a gum print is a function  of the insolubility of the 
> hardened gum.  If the print dissolves when  wet, that's not a permanent 
> print.
>
> Katharine
>
>
> On Apr 23, 2010, at 9:41 AM, Paul Viapiano wrote:
>
>> Christina...
>>
>> These are all very good questions.
>>
>> Personally, I like to put down at least two layers before PVA  sizing. I 
>> have noticed that the layer after the size has a harder  time adhering, 
>> hence I should probably expose more or develop for  less time. But then 
>> again, there are so many variables going on in  any print, that I haven't 
>> taken the time to try and pin it down.
>>
>> I think that someone (Keith Gerling) also mentioned a while back,  that 
>> he found layers were less stable when re-wetted. Would things  be more 
>> stable if we exposed the print to UV after drying each  layer? Just a 
>> thought here...
>>
>> I don't know if the print really sits on top of the PVA any more  than 
>> the gelatin. I look at it as just helping the already-sized  paper along 
>> as its original size gets diluted with repeated  soaking. This is all 
>> very unscientific of me but is what I'm thinking.
>>
>> Paul
>>
>> ----- Original Message ----- From: "Christina Anderson" 
>> <zphoto at montana.net>
>> To: "The alternative photographic processes mailing list" <alt- 
>> photo-process-list at lists.altphotolist.org>
>> Sent: Friday, April 23, 2010 6:31 AM
>> Subject: [alt-photo] Re: IDEA? NEW ALT PHOTO BOOK
>>
>>
>>
>>> Bob,
>>>
>>> I think it could be a good thick chapter of a book...
>>>
>>> I am probably opening up a can of worms here...
>>>
>>> I've been using the Gamblin PVA size now and taught it to my class  this 
>>> semester in place of glutaraldehyde hardened 2.8% gelatin  (6ml of 2.5% 
>>> per liter), and it is a great teaching method and  really user friendly. 
>>> Boy was my life easier--no hot plate,  massive sizing day, mess, 
>>> toxicity.  PVA you can just "size as you  go". It is the "magic bullet" 
>>> of teaching for sure.
>>>
>>> I use it 1+2 on Artistico.   I found more issues with staining  with PVA 
>>> than with glut/gelatin but that I think is specifically  related to 
>>> having to determine the dilution of PVA for each  specific paper.  I 
>>> almost think Fabriano might benefit from either  a 1 + 1.5 or an 
>>> intermediate layer of sizing between multiple  coats. But at a point, 
>>> then, PVA becomes too slick and plasticy.
>>>
>>> However, after having worked with it all semester I slightly  prefer 
>>> glut/gelatin.  **But** I am not sure I prefer the latter  enough to go 
>>> to all the trouble to do it.  With tray sized sheets  gelatin is no big 
>>> deal, but with 15x22 size sheets it is a pain.  PVA wins, hands down, 
>>> for user-friendliness.
>>>
>>> I will be finishing up two large gum projects this summer so we'll  see 
>>> by the end of summer how I feel--if I go back to gelatin in my  own 
>>> work, in other words.  I will continue to teach the non-toxic  PVA 
>>> method, but parts of me think I should still at least show  students 
>>> traditional sizing because of a concern I am feeling.
>>>
>>> My concern is this:  when I take a print out of the water to hang  to 
>>> dry, even the border of the print is what I would call 
>>> "unstable"--meaning a fingerprint on it will mar it quite  extensively 
>>> in a way I have not seen with gelatin sized paper.  Anecdotally, a 
>>> rewetted PVA print SEEMS also less stable--layers  still manipulatable. 
>>> Is that an issue?  I don't know. My question  is does each layer you do 
>>> of dichromated gum on top of a layer of  previously hardened gelatin 
>>> also affect the gelatin below (another  colloid) and does it, in fact, 
>>> affect a layer of PVA in the same  way?  Or can the layer of gelatin 
>>> even GET rehardened repeatedly  with each succeeding layer of 
>>> dichromated gum or is it hardened  once and for all with the glut and 
>>> that is it--successive layers  do nothing?
>>>
>>> Or is this just a "hydrophilic" thing, or that gum is (how would  you 
>>> say) "attracted" to PVA in the same way it is to a surface of  gelatin? 
>>> Are, in effect, PVA and gelatin truly interchangeable in  sizing or is 
>>> it possible that each layer of hardened gum has  better adhesion to a 
>>> layer of gelatin vs. a layer of PVA, probably  only visible at the 
>>> microscopic level?
>>>
>>> Maybe the scientists of the list can answer these questions and  put my 
>>> mind to rest, because my lurking fear is that the gum print  on top of 
>>> the PVA may not be as stable in the long run as one on  top of gelatin. 
>>> A non-scientific test I will do in a couple  months is soak a PVA'ed 
>>> print and a gelatin-sized print, old ones,  side by side, and scratch 
>>> and see the results. But I don't know if  that proves anything.
>>>
>>> I hope someone will come on list and say this fear is completely 
>>> unfounded, that both sizings create equally stable final prints.  But I 
>>> am worried the gum print sits on top of the size instead of  melds into 
>>> it.
>>>
>>> I have no answers, just asking the hard questions....on this quest  for 
>>> the most perfect, easiest size.
>>>
>>> Now, as far as other processes aside from gum....salt...hmmm....
>>>
>>> Chris
>>>
>>>
>>> Christina Z. Anderson
>>> christinaZanderson.com
>>>
>>
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