Re: clearing dichro stain with sulphuric acid was Re: (Gum) Tonal scale

Yves,

I think there is always a stain, The stain left by the sulphuric acid
is not heavy is but a light grey in colour you will need to have a
heavy brown oxidised stain intialy to be aware of it.I find it very
useful in maintaing Tricolour balance

Pete back from he

On 7 Dec 2005, at 09:23, Yves Gauvreau wrote:

> Pete et all,
>
> I don't know if you saw Katharine experiment (link below) or not but
> the
> reason I ask the question was to find out if the one(1%) solution of
> sulphuric acid you've been using all these years would leave a
> noticable
> tone like the NaCl and the other stuff did leave???
>
> Yves
>
>
> ----- Original Message -----
> From: "peter" <temperaprint@blueyonder.co.uk>
> To: <alt-photo-process-l@sask.usask.ca>
> Sent: Tuesday, December 06, 2005 9:35 AM
> Subject: Re: (Gum) Tonal scale
>
>
>> Dear Yves.
>>
>> I have used a one(1%) solution of sulphuric acid to clear the brown
>> dichro stain for the past twenty years with no ill effect in both Gum
>> and Temperaprint.
>>
>> Best wishes
>>
>> Pete
>>
>>
>>
>>
>> On 6 Dec 2005, at 00:38, Yves Gauvreau wrote:
>>
>>> These are very interesting results Katharine, thanks for sharing them
>>> with
>>> us.
>>>
>>> I ear that some acid (sulfuric acid maybe) could help to clear the
>>> dichromate, I'd be curious to see or ear about a similar test using
>>> it???
>>>
>>> Thanks
>>> Yves
>>>
>>>
>>>
>>> ----- Original Message -----
>>> From: "Katharine Thayer" <kthayer@pacifier.com>
>>> To: "alt photo" <alt-photo-process-l@sask.usask.ca>
>>> Sent: Sunday, December 04, 2005 9:50 AM
>>> Subject: Re: (Gum) Tonal scale
>>>
>>>
>>>> I accidently sent this to myself instead of to the list, (still
>>>> figuring out my new mail program) so I'm sending it again, to you.
>>>>
>>>> On Dec 3, 2005, at 1:00 PM, Katharine Thayer wrote:
>>>>
>>>>>
>>>>> After I wrote that about dichromate stain, I remembered that I
>>>>> have a
>>>>> page showing the color of unstained gum, of dichromate-stained, and
>>>>> of
>>>>> cleared stained gum, on my site; here it is if anyone is
>>>>> interested:
>>>>>
>>>>> http://www.pacifier.com/~kthayer/html/gumcolors.html
>>>>>
>>>>> The samples don't show different tones, because it was gum that
>>>>> was
>>>>> exposed without a step tablet or any kind of negative, just
>>>>> hardened
>>>>> gum. that's when I was working on that project of making gum for
>>>>> chemical analysis.
>>>>> kt
>>>>>
>>>>
>>>
>>>
>
>
Received on Fri Dec 9 07:21:09 2005