This page will turn into a complete chapter at some point. This material augments the rest of the chapter. It is not necesary to test you paperr before proceeding before testing film, but there are advantages to doing so. If you do not test paper, just use the commonly recommended densities for your targeted normal density.

The following snippet of a question is from a reader:
[I printed] on Cachet VC at grade 2, developed in Ansco 130 1:1 for 3 min, I obtained a sharp gradient from zones 3 through 8 or 9, with Dmax at Z3, and Dmin at Z8 or Z9. I haven't found any material on this dilemma, and would welcome your thoughts.
The issue is that the film density range is not matching the exposure range of the paper/paperdeveloper/enlarger combination in your darkroom. In effect, you must determine the appropriate film densities for a particular paper and darkroom.
Heretofore, we have proceeded on certain assumptions. We have assumed that the appropriate density for Zone 8 is such-and-such if you are using a condenser enlarger and such-and-such-plus if you are using a diffusion enlarger. That model is a good one and works broadly, but it will not fit every paper/paper developer/enlarger combination.

We are going to find two numbers that will be associated with your paper. Work carefully. Use fresh chemistry. Be very consistent. Wear the same dark clothes during all tests (reflection can be an issue), don't smoke in the darkroom, etc.

For the tests below, make sure that the light striking the paper is evenly distributed. A full sheet of paper should have even tonalities. It is probably best to project a larger area than the size of the easel. That will allow you to use the middle of the projected area. The middle area is typically more evenly illuminated than the overall area.

Very , very carefully measure the most light, in seconds, that leaves no visible density after final processing (including toning) and drying. Try to arrange your enlarger height and fstop so that this amount of light is as close as possible to 1.0 - 1.5 seconds. Your result should be accurate to within 1/10 of a second or better if possible. It may help to make small marks on the paper with a pencil to help you locate the divisions of the test print.

Call it: max_exposure_for_minimum_density

Very, very carefully measure the least light, in seconds, that produces Dmax after final processing. Try to arrange your enlarger height and fstop so that while the other number is as close to 1.0 seconds as possible, this number does not cause the exposure to move into the range where reciprocity effect must be accounted for your paper. Normally, I think you are safe to expose at least 30 or 40 seconds. Hopefully the paper manufacturer can help with reciprocity information for your paper. If the enlarger height/fstop must be compromised, compromise here, instead of for the other exposure - (to find max_exposure_for_minimum_density). Try to determine an exposure that is accurate to within a second or two if possible. It may help to make small marks on the paper with a pencil to help you locate the divisions of the test print.

If your exposure did reach into the realm of reciprocity corrections, use the corrected number. For instance, if you had to expose 80 seconds, but the paper required a 1.5x reciprocity effect correction, count the exposure time as 80/1.5 = 53.3 seconds.

Call it min_exposure_for_maximum_density.

Now make the following calculations:

min_exposure_for_maximum_density / max_exposure_for_minimum_density

The number represents the exposure range of the paper.

	Let's keep an example going:
	--
	Example stage 1:
	
	min_exposure_for_maximum_density = 38 seconds
	max_exposure_for_minimum_density = .9 seconds
	paper range = min_exposure_for_maximum_density / max_exposure_for_minimum_density
	paper range = 42.2
	--

Next take the Log-Base-10 of that number. The number you get will be the density range of paper expressed in the same units as film density.

	--
	Example stage 2:
	
	log-base-10(42.2) = 1.623249
	round to 1.62
	paper range = 1.62
	--

The number will represents the difference between a Normal Zone 10 density and a Normal Zone 0 density.

A reasonable estimate for a Zone 0 density is about .04. In our example, the appropriate density for Zone 10 will be Zone 0 + paper range or 1.66 .

	--
	Example stage 3:
	
	paper range = 1.62
	normal Zone 0 density = .04
	Zone 10 density = 1.62 + .04
	Zone 10 density = 1.66
	--

Now test film carefully until you get could consistent results with Zone 0 = .04 *and* Zone 10 = 1.66, This is your normal development time for that paper.

Now work backwards slightly, carefully expose a roll at Zone 0 through 10, note the densities for each value. Do your remaining tests using the Zone 8 and other densities you have derived here. It will be accurate for your paper, enlarger and paper developer. It will be accurate for your paper, enlarger and paper developer. Under conditions of
a proper proof, it will cause your paper to show Dmax at print value (Zone) 0 and Dmin at print value 10. The gradient in between may still be steep in the middle or it may not. The paper will not respond linearly to light. It will have toe and shoulder areas that cannot be predicted from this particular test.

Think of a grade two paper as having an exposure range
somewhere around 1.75 and 1.80. That value will vary with the specific brand of paper. So our example paper, with the exposure range of 1.66, would have a slight bit more contrast than expected for a Grade 2 paper. It has more contrast because the paper needs a shorter range of light to reproduce the complete grayscale.

There are other benefits to knowing the exposure range of your paper. If you have access to a densitometer, you can measure the density range of a negative and match it to a paper/paper developer combo with a similar exposure range. This will not alleviate the need for dodging and burning, and it certainly does not mean that you can determine the best paper to use by numbers (you can only judge that by critical observation of the print). However, it will help you start with a paper that is approximately matched to your negative. It might save a test print or two on every negative, that is a cool thing.

Also, it must be noted that two papers with the same exposure range will not print the a negative the same way. One paper may exaggerate tonal separations in the shadows, another may exaggerate tonal separations in the midtones and a third may emphasize some other area. Yet all of these papers could have the same exposure range as calculated here. Zone 8 on one paper may be lighter or darker than Zone 8 on another paper. Likewise, other print values will differ. These are the differences that make printing such an amazing exploration of the image.