Re: contrast in large format B&W negatives.

Tmax films are very sensitive to development time, temp, and agitation. Far
more than most other films. The usual way to overdevelop film for alt
processes is to significantly increase the time the neg is in the developer.
This will give more control and work on almost all films. Changing agitation
will not "significantly" change most films.

Pinhole negs need more time in developer than lens negs. At least mine do!

Your correct development time for an alt process is determined by the type
of scenes you shoot, how far into reciprocity you expose, what film
developer you use, the paper you print on, and the chemicals you coat with,
what light source you print with...... get the (complicated) idea?? But, as
a starting point, try adding 50% to the time suggested by the manufacturer
for cyanotype negs and 100% for platinum negs. If the time for your film /
developers according to the manufacturer is 6 minutes, use 9 minutes for
cyanotypes and 12 minutes for platinums.

Also for alt prints you will be happier with a bit of overexposure. For alt
prints I meter and shoot HP-5 (a 400 speed film) at 125.

Hope that helps.

-- 
Tom Ferguson
http://www.ferguson-photo-design.com
> From: "William Erickson" <erickson@ic.mankato.mn.us>
> Subject: [pinhole-discussion] contrast in large format B&W negatives.
> 
> I've been using large format pinhole negatives to do alternative process
> printing. I've been aware for some time of the extent to which I can
> influence the contrast of a tray-processed TMAX negative by the amount of
> agitation I provide. I understand that TriX is much less susceptible to
> contrast control this way, but I've never tried it. I just tried some Ilford
> HP5 5x7 negatives intended for cyanotypes and palladium printing, and found
> much less contrast than I expected with what I thought was over-agitation.
> Any thoughts?