Maximum Development Time Test (MDT)
Determining the maximum development time is important to determine the point at which highlights stop
developing and the paper begins to fog.
How To: Determine MDT
- Cut a sheet of papper into 6 strips and number them on the back 0 to 5. This should be done in safe light
conditions.
- Place the piece marked #0 directly into the fix (1 minute in bath 1, 1 minute in bath 2).
- Place the piece marked #1 into the developer for 1 minute, then stop and fix normally.
- Place the piece marked #2 into the developer for 2 minutes, then stop and fix normally.
- Place the piece marked #3 into the developer for 3 minutes, then stop and fix normally.
- Place the piece marked #4 into the developer for 4 minutes, then stop and fix normally.
- Place the piece marked #5 into the developer for 5 minutes, then stop and fix normally.
- Let all paper fully dry.
- Under a bright light, examine all the strips and compare strips 1-5 with strip 0.
Examing The Strips
While examing the strips under bright light, you will notice a tone on at least one of the strips. Where you
start to see a tone, you have exceeded the maximum development time for that paper, and are fogging the paper.
Notes
- It may be possible that none of the pieces are showing any tone, if this is the case, repeat the
test with longer times.
- You can fine tune your test down once you've found approximately the minute paper begins to fog. This is
especially important when your MDT is close to your MBDT.
Maximum Black Development Time Test (MBDT)
All photographic paper has a maximum black point, where the paper after being in the developer for a certain
length of time will not get any blacker. This is usually called the DMax. It is helpful to know this
on papers so we know when we've reached our DMax and can't get anything more out of them.
How To: Determine MBDT
- Expose a piece of paper to maximum black as determined by a test strip (the point at which you don't see the
blacks getting any darker).
- Cut paper in to 5 strips, and label each one (1-5).
- Place the piece marked #1 into the developer for 1 minute, then stop and fix normally.
- Place the piece marked #2 into the developer for 2 minutes, then stop and fix normally.
- Place the piece marked #3 into the developer for 3 minutes, then stop and fix normally.
- Place the piece marked #4 into the developer for 4 minutes, then stop and fix normally.
- Place the piece marked #5 into the developer for 5 minutes, then stop and fix normally.
- Under a bright light, examine all strips and compare them to find the shortest
time at which the maximum black has been hit. It may be easier to do this when the paper is still wet.
Notes
- It is possible that the MBDT may be longer than the MDT, if this is the case, this paper/developer combination
is not recommeneded.
- It may be that there is no difference in blacks even at one minute, thus, it has a very fast MBDT.
- The greater the time between the MBDT and the MDT, the greater the flexibility of the paper.