Re: Sizing paper with gum and dichromate, was Re: glut

Hi Yves,
I'm sorry, I don't have a clue why I get clear gum and others don't. I
used to think it had something to do with the light, but it sounds like
you didn't get clear gum with the same light, so that's not it. I'm
about out of ideas for why things happen in gum, at the moment. I know
you want definite answers for all your questions, and I applaud your
curiosity and persistence, but definite answers that generalize to the
universe of gum printers and gum printing are very few and far between.
  All I know, and all I can say, is what works for me, and I'd say that
your best bet, if you really want to learn gum printing, is to set out
and see what works for you. That's just how it is with gum, sorry,
Katharine

On Dec 15, 2005, at 6:46 AM, Yves Gauvreau wrote:

> Hi,
>
> thanks to all who replyed to my question. I'd like to add, Katherine
> showed
> us a gum dichro layer that at least from the scan I've seen didn't
> show any
> apparent color like Kees and Loris mention. Maybe she could tell us the
> "secret" of getting a clear unstained gum layer. From what she said I
> think
> it's all a question of exposure but I've been known to misinterpret
> her and
> others writing before, thus maybe it's better to wait for her own
> words on
> this.
>
> Thanks again
> Yves
>
>
>
>
>
> ----- Original Message -----
> From: "Kees Brandenburg" <ctb@zeelandnet.nl>
> To: <alt-photo-process-l@sask.usask.ca>
> Sent: Thursday, December 15, 2005 9:26 AM
> Subject: Sizing paper with gum and dichromate, was Re: glut
>
>
>> Loris, Yves and others,
>>
>> I tried gum sizing too and got the same greenish stain that would not
>> clear even after a long(er) disulfite bath and wash. Probably I
>> overexposed. But why not standardize things a little bit more and size
>> with gum and expose with your standard printing time through a clear
>> sheet of printing substrate (or film). I'll give that a try this
>> week. I
>> do like my gelatin/formalin or gelatin/glyoxal sized papers but
>> there's
>> allways a different 'feel' in the first (gum on gelatin) and the
>> subsequent (gum on gum) coats.
>>
>> -kees
>>
>>
>>
>> Loris Medici wrote:
>>
>>> IME, the practice of sizing with gum has the risk of dichromate
>>> staining
>>> unless you expose very carefully. When I coat the paper with
>>> unpigmented
>>> gum + dichromate mixture and expose it 30 secs without the negative +
>>> contact printing frame combo (my normal exposure with negative and
>>> contact printing frame is 360 secs / 6 mins. In other words: I expose
>>> the unpigmented gum + dichromate mixture ~ 3.5 stops less when
>>> sizing...), I get a slightly greenish / grayish surface (very slight
>>> and
>>> subtle, but you can see it clearly), not paper white. Probably I
>>> should
>>> expose less in order to get rid of the stain (or reduce it further)
>>> but
>>> if I do so, I may get suspicious about the effectiveness of the
>>> sizing.
>>> Therefore, I size with gelatine and harden in formalin. (BTW, I
>>> should
>>> admit that: I never tried to use paper sized in that manner - I mean
>>> for
>>> gum printing, I didn't like the cyanotypes I've made on paper sized
>>> with
>>> gum dichromate - and dumped that method when I saw the stain + my bad
>>> experience with Cyanotype... I also didn't tried to establish a
>>> non-staining exposure time - I guess I was lazy back then).
>>>
>>> Regards,
>>> Loris.
>>>
>>> -----Original Message-----
>>> From: Yves Gauvreau [mailto:gauvreau-yves@sympatico.ca]
>>> Sent: 15 Aralık 2005 Perşembe 14:31
>>> To: alt-photo-process-l@sask.usask.ca
>>> Subject: Re: glut
>>>
>>>
>>> Hi,
>>>
>>> out of curiosity, would there be a "problem" sizing with gum instead
>>> of
>>> gelatine especially if you intend to do gum printing later???
>>>
>>> Yves
>>>
>>> PS Aren't we suppose to sent our message in plain text...
>>>
>>>
>>>
>
Received on Thu Dec 15 12:30:58 2005