try cook it this way: twenty celsius degrees for about fourteen minutes
std agitation, if you're on a difflight source. but maybe that
eighteen-twenty same temp 1+1 D23/water will raise up shads a bit
without loose highs. I think D23 is right to cutoff some grain from tx.
sorry can't help you if you are on condlight side. only because I think
condlight is a dog. time ago got good with push tx [new], it was a
grainy stuff to do: lot of celsius, lots of agitation, HC/rod
fiftyfifty. if you want can show you how grainy.same job on D23 was
completely different: less grain, better highs control, lower contrast,
precious shads, easy to print for a more conventional sight.
see you.

Maybe with good reason. D23 is a soft working developer needing
about 1/2 stop more exposure than D76. It is not the thing I'd use
to push a fast film for two stops. Maybe it can be done, but I wouldn't
try it. Use something with phenidone in it like Xtol or Microphen.

Martin

The speed of Tri-X in D23 is about 250. If you need 1600, try T-Max 3200.

In a world that includes Diafine, why would you go to this kind of
trouble to get 400TX to EI 1600?  Three minutes in Bath A, three minutes
in Bath B, water stop, and fix.  You're hanging the film before D-23
would be through developing it for a two-stop push, and you get better
shadow detail, about a full stop of toe speed increase (so your contrast
looks like a one-stop push, not two stops).  Of course, if you're trying
for grain that looks like driveway gravel, you want a low-solvent
developer; try HC-110 Dilution G (1:119 from USA syrup), stand developed
for 90 minutes.

  Pushing any film 2 stops is going to be marginal no
matter what developer is used. The ISO speed of a film is
about its maximum for good shadow detail. What happens when
film is pushed is that the overall contrast is raised. Of
course the toe, or shadow part of the curve, is also
increased in contrast. This gives the effect of higher speed
for the shadows but results in excessive contrast for parts
of the film receiving anything like normal exposure. Tri-X
roll and 35mm film, i.e., the ISO-400 stuff, pushes
reasonably well but you would do better with a faster film
like T-Max P3200 or Ilford's equivalent. These are films
with ISO speeds of around 800 to 1000 but which deliver good
quality when pushed.
  There is some variation in the speed delivered by various
developers. D-76/ID-11 is the benchmark. Some Phenidone
containing developers will deliver about 3/4 stop greater
speed (depending on the film) for a given contrast index.
Among such developers are Kodak T-Max and T-Max RS, Kodak
Xtol, Ilford Microphen. Some developers lose a little speed,
Rodinal is an example. D-23 and D-76 have very similar
properties other than D-76 has greater capacity. ]
  Generally pushing film will increase the grain. There is
not much that can be done here. Probably Xtol is the finest
grain of the above, T-Max the best for greatest speed, but
coarser grain. The tonal rendition will be distorted
regardless of the developer because that comes from the
increased overall contrast of pushing.
  Some mistatements are often made about some developers.
The sulfite in D-76 and D-23 acts as a solvent for the
silver halide in the emulsion. In these two developers the
solvent effect is such that it _increases_ film speed
slightly because it makes more development centers in the
halide crystals available to the developer. In developers
like Microdol-X or D-25, used full strength,  which are very
inactive, the solvent has time to destroy some of the latent
image, lowering the film speed. This does not happen in D-23
or D-76 or other similar developers.
  The ISO speed of black & white negative films for still
cameras is measured in a way that results in the lowest
exposure consistent with adequate shadow detail. It assumes
an average contrast that is too high for many users. When
the contrast is lowered (or raised) the ISO speed is no
longer valid. Most films have only about one stop latitude
for underexposure but a great many stops (as many as 12 for
some films) for overexposure. Latitude is the amount of
error in exposure than can be made and still have negatives
with good tonal rendition. This is why its better to use a
faster film than to push a slower one. At some point the
film just runs out of sensitivity and there will be no image
regardless of the kind of developer or the amount of
development, you will just increase the fog level.
  For your application I would suggest T-Max P3200 and
Xtol.
  Now, for pushing, the rule of thumb is to increase
development time about 1.5 times for about a one stop
increase in effective shadow speed. This will also increase
overall contrast about one paper grade. For two stops
increase time to about double normal, maybe a bit more. This
will increse contrast about 2.5 paper grades. The time
variation changes with film and developer. Tabular grain
films like T-Max, Delta, and Fuji Acros, change contrast
faster with time than do conventional films.

    Two stops is about the maximum you can push most films.
D-23 is probably not the best choice for pushing. T-Max RS
or Ilford Microphen is a better choice. About double the
normal time will be right. Note that there is not really a
speed increase. What you are doing is to increase the
contrast. The low exposure part of the film curve (the toe)
has lower contrast than the rest so increasing its contrast
will make low exposures printable, of course, it also
results in very high contrast for normally exposed objects
in the picture. There is a limit to the inherent sensitivity
of the emulsion. If there is not enough light NO image is
recorded and no amount of pushing will bring one out. If you
have no choice of film 1600 is just about the limit for
Tri-X (roll and 35mm version). If you do have a choice try
T-Max P3200. At EI 1600 it will have better tonal rendition
and probably finer grain than highly pushed Tri-X.