Test strip printing is vital for many reasons, mainly to verify the amount of time the paper is needed to be exposed under the enlarger. By cutting a sheet of RC paper into 2″x8″ strips, you cut down on the amount of waste considerably. Close the aperture of the enlarger lens somewhere between f8 and f16 (depending on the lens and the type of exposure you want), and switch off the light in the enlarger.
Place a single strip of RC paper onto the easel of the enlarger. Place it on an area where there are similar tones. This is to identify the adequate amount of time needed the negative to be exposed correctly on the paper. The test can be done by using a large piece of black card that does not allow any light to pass through, and holding it just above the strip covering it all except for about an inch at one end. Switch on the enlarger and expose the uncovered strip for at least five seconds.
After the first five seconds, expose another inch of the strip for five seconds, repeat this until the entire strip has been exposed under the light. Switch off the enlarger and immerse the strip into the developer, the paper should be at least one minute in the developer before you remove it. Do not remove the paper as soon as the image appears, as it will not be fully developed.
Read the instructions on your developer container to get the minimum and maximum developer immersion times. You will notice that the image on the test strip appears as different exposures identifiable as being very dark at one end and little exposure on the other end in rectangular sequences.
After the developing time has completed, place the strip into the stop bath to cease the developing process, and after a minute or two remove the strip from the stop bath and place in the fixer bath. The fixation period is usually three to five minutes (again, depending on the make of fixer used). Once the fixation time has elapsed place the strip in the bath of water to wash for ten minutes.
The final step is to study the strip to see what the best exposure time is. Check that all photo paper is sealed up and safe before you switch on the main light to have a proper look at the test strip. The correct time should be quite easily identified by nice even tones with no overly dark or light areas. Each rectangle on the strip represents an extra five seconds exposure.
Source by Beno Goldfarb