[pure-silver] Re: Modified Agfa 108 with multigrade paper
- From: hksvk <hksvk@xxxxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Thu, 15 Mar 2007 18:37:35 -0500
Thank you for your helpful responses, especially the one correcting my
notion that I should be able to increase contrast to the extent I want by
using a high contrast developer with the same paper.
I am using the El-Nikkor 105f5.6 enlarging lens. Isn't this a pretty good
one? It shouldn't be a cause for uneven or irregular densities, should it?
When intensifying a negative with Kodak Rapid Selenium Toner, is it
necessary to first treat it to 'harden' it, ie., to prevent blotching or
other unevenness? with formaldehyde?
Harry
>
>
>> I have the following formula for Agfa 108 paper developer:
>> metol...5
>> grams/liter, sodium sulfite...40 g/l hydroquinone...6
>> g/l potassium
>> carbonate...40 g/l potassium bromide...2 g/l
>>
>>
>> I have tested this Agfa 108 with Ilford multigrade fiber
>> paper without (for
>> reasons detailed below) a polycontrast filter , but find
>> that my prints need
>> more contrast than this already high contrast developer
>> provides. So, in an
>> effort to gain contrast, I have modified the developer as
>> follows: reduced
>> metol to 2 grams/liter, increased hydroquinone to 14
>> grams/liter, and, for
>> the accelerator, substituted 4 grams/liter sodium
>> hydroxide for the
>> potassium carbonate.
>>
>> Having seen no substantial gain in contrast with these
>> modifications, I then
>> increased the bromide in 1 or 2 gram/liter increments
>> until reaching 10
>> grams/liter potassium bromide. Still, I am seeing no
>> appreciable increase in
>> contrast.
>>
>> Is there something about modern paper emulsions that makes
>> them unresponsive
>> to these strategies to increase contrast? Or is this
>> problem due to some
>> property of the multigrade paper? Would a modern graded
>> paper respond to
>> these manipulations?
>>
>> The 2.25 inch square negatives I am printing from require
>> absolutely even
>> edge-to-edge and corner-to corner illumination from the
>> light source of my
>> Beseler 4x5M series enlarger with condenser head and PH212
>> lamp. With no
>> negative in the glassless negative carrier, when I expose
>> a sheet of the
>> 16x20 paper at a very low density (zone 8 or so), I get a
>> pattern of
>> increased density, even after improving the unevenness of
>> illumination that
>> I encountered initially. The polycontrast filter that I
>> would require (3.5
>> or 4) exaggerates this unevenness and makes it too
>> apparent when printing
>> from the negative. These negatives are extremely
>> nerve-wracking if not
>> impossible to dodge and/or burn in.
>>
>> I know, one solution would be to produce a set of more
>> contrasty negatives,
>> but this would be very difficult to do.
>>
>> Is there someone on the list who could kindly help me with
>> this problem? If
>> a graded paper might work for me in this situation, is
>> there one that could
>> be recommended?
>>
>> Many thanks.
>>
>
> Since paper emulsions are developed to obtain maximum
> density the contrast is pretty much a matter of how the
> emulsion is made. There is only a very narrow range of
> variation possible with change in developer. Modifying a
> developer as above will probably only make it work faster.
> If you don't have printing filters for the paper you can
> try using camera filters over the enlarging lens. A blue
> filter will expose mostly the high contrast part of the
> emulsion, a Green or yellow filter will give you low
> contrast. You will probably have to make partial exposures
> through two filters to obtain the contrast you want. Most VC
> papers are around Grade 2.5 with no filter on a typical
> tungsten lamp enlarger.
> Note that the method of increasing the printing contrast
> will make no difference in the uniformity of the
> illumination, anything which increases printing contrast
> will exagerate illumination problems, including the inherent
> drop-off of the enlarging lens.
> There is some benifit from using a long lens. The
> drop-off will be less because the image angles will be
> smaller. A long lens will require refocusing the condenser
> for best uniformity. If you have an enlarging exposure meter
> it will help to get the illumination uniform. If the problem
> is only drop-off toward the corners or edges you can burn in
> the corners. I have to do this routinely when using a 135mm
> lens for 4x5 negatives unless I am cropping them a lot.
> If the illumination is blotchy check the condensers for
> blemishes or dirt. Also, if you are using a glass-sandwich
> negative holder the increased contrast will also exagerate
> any dirt or blemishes on the surfaces. If the glass is not
> good quality optical glass you may also be bringing up
> uneven transmission due to inhomogeniety in the glass.
> Another approach is to intensify the negatives. There is
> always a hazard in any chemical treatment of a negative but
> it is fairly safe to use Selenium toner. It is capable of
> increasing contrast perhaps a paper grade and will protect
> the image. Use KRST at 1:9 or even a bit stronger. It will
> work slowly enough to be controllable at this dilution. Many
> other intensifiers do not produce permanent images or can
> damage the emulsion or have other vices but KRST is pretty
> safe. Kodak Brown Toner is also safe and will result in well
> protected images but I don't know how much intensification
> it produces.
>
> ---
> Richard Knoppow
> Los Angeles, CA, USA
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