[rollei_list] Re: OT: development
- From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
- To: <rollei_list@xxxxxxxxxxxxx>
- Date: Fri, 20 May 2005 16:01:34 -0700
----- Original Message -----
From: "Allen Zak" <azak@xxxxxxxxxxxxxxx>
To: <rollei_list@xxxxxxxxxxxxx>
Sent: Friday, May 20, 2005 3:06 PM
Subject: [rollei_list] Re: OT: development
>
> On May 20, 2005, at 4:21 PM, Richard Knoppow wrote:
>
>>
>> ----- Original Message -----
>> From: "Bob Shell" <bob@xxxxxxxxxxxx>
>> To: <rollei_list@xxxxxxxxxxxxx>
>> Sent: Friday, May 20, 2005 12:17 PM
>> Subject: [rollei_list] Re: OT: development
>>
>>
>>>
>>> On Friday, May 20, 2005, at 02:57 PM, James Davis
>>> wrote:
>>>
>>>> Sorry to follow myself up, I presume that the Ilford
>>>> equivalent (for my
>>>> local store stocks Ilford) is Ilford Wash Aid? It's not
>>>> clear from
>>>> their
>>>> literature that it's sulfite based.
>>>>
>>>
>>> I never use a wash aid with film. Fixing the film
>>> longer
>>> and washing
>>> properly will get rid of any residual dye. The wash aid
>>> won't hurt
>>> anything, but I don't think it is really necessary. I
>>> do
>>> use it on
>>> fiber based paper prints, though.
>>>
>>> Bob
>>>
>>> ---
>> It has the same benefit for film as for paper in that
>> it
>> makes some othewise insoluble fixing reaction products
>> soluble, or at least releases them when they are bound up
>> to
>> image silver or the gelatin. This has the effect of
>> extending fixer capacity and insuring complete fixation.
>> Wash aid also helps to conserve water where that is
>> desirable by reducing film washing time from 30 minutes
>> to 5
>> minutes.
>>
>> ---
>> Richard Knoppow
>> Los Angeles, CA, USA
>> dickburk@xxxxxxxxxxxxx
>
> Ilford recommends fixing with non-hardening rapid fixer,
> no wash aid,
> then washing with a technique that usually takes about 5
> minutes or
> less and uses about three pints (@ 1.5 liters) of water
> per roll of
> film, assuming SS Nikor style tanks and reels. That's
> what I have been
> doing for the last decade or so. It is probably too early
> to determine
> how well my negatives will last, but I'm also old enough
> to not really
> care. Fortunately, my earlier B&W was processed strictly
> to Kodak
> specs, which included a wash aid ( Perma Wash) and
> therefore will
> outlast all meaning.
>
> Allen Zak
>
> ---
> Rollei List
I am not certain what is in Perma-Wash. At least one wash
aid on the market seems to be composed of a detergent. I
have no idea if this stuff works. I have the vaguest memory
of reading an article or paper on detergents as wash aids
long ago but have not seen anyting recently. Lets say I am
suspicious of it.
The test for completeness of washing is the Silver
Nitrate test. There are others which are most sensitive but
the Silver Nitrate test will show whether the prints have
excessive hypo in them. The method is very simple but a more
elaborate version, in which the stain spots are fixed, can
be used with a densitometer for quantitative measurements.
All this stuff is in Kodak literature somewhere.
Ilford's procedure is premised on the idea that fixing
time should be so short that hypo can not work its way into
the paper fibers. Washing is a diffusion process except for
this condition of paper base. Once the hypo becomes adsorbed
onto the interstices of the fibers they tend to bind there
and it is at least partially a frictional process to remove
them. Sulfite acts as an ion exchange for thiosulfate so
tends to force it out of the fibers. Ilford found that if
the fixing process could be completed in less than a minute,
preferably in no more than 30 seconds, the hypo did not
become bound up in the fibers. After 2 minutes the deed is
done and washing must be done conventionally. One problem is
that no all paper will fix out in one minute or less.
Ilford recommends a ten minute treatment in sulfite wash
aid followed by a five minute wash. Ilford also has a water
saving method of using successive baths of water. Kodak has
a similar regimen but Ilford's probably uses less water.
Such a system of successive baths can give perfectly
archival washing but has no advantage over running water
other than conservation of water and utility where running
water is not available.
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
---
Rollei List
- Post to rollei_list@xxxxxxxxxxxxx
- Subscribe at rollei_list-request@xxxxxxxxxxxxx with 'subscribe'
in the subject field OR by logging into www.freelists.org
- Unsubscribe at rollei_list-request@xxxxxxxxxxxxx with
'unsubscribe' in the subject field OR by logging into www.freelists.org
- Online, searchable archives are available at
//www.freelists.org/archives/rollei_list
Other related posts:
