You asked:
> When I
>try and print friends "silver" negs (a lot flatter and thinner than mine) I
>always end up way off (always too dark).
It is not a matter of reciprocity failure.
When you are dealing with papers where the light sensitive materials sit at the
surface of the paper and within it, rather than in a layer of gelatine on the
surface, self masking comes into play. The light sensitive salts at the surface
of the paper darken first at the surface under the thinnest parts of the neg to
act as a mask slowing down the action of the light on the salts under the
surface of the paper so that more time is available for the light to affect the
salts under the denser parts of the neg. This gives a straight line with good
prints from negs up to a density well past 2.0.
If all the negative is thin then the whole of the print darkens.
Thus, by using very dense negatives with good gradation I am able to obtain the
contrast range and gradation that I usually want from a platinum palladium
print.. If I want a gentle print with a limited range of tones I use a thin
neg and give it less exposure or use a less concentrated sensitiser.
>2) More neurocis, what can I use to clean the black stain (platinum??) from
>the small beaker I mix my platinum chemicals in?? EDTA in normal
>concentrations does't do it, strait stop bath doesn't do it, grocery store
>silver polish doesn't do it. I assume that pure platinum might be a
>comtaminant (??) and thus would like to keep this cleaner.
Beaker seems to imply that you are not using glass. If that is true it is not a
good idea. I make a habit of using glass or ceramics.
I use a china plate and coat with a brush. But that is just my preference.
I have a question too.
What effect on contrast do different developers have on platinum/palladium
develop out prints ? Even if it is in the archive could we have a brief
resume as the searchable archive is trying to find a new home.
Terry King