The objective of the experiments was to determine the amount of time required to reach maximum black (or rather in the case of Cyanotypes, blue) when exposed under a sun tan lamp. The contraption shown in one of my previous posts has allowed me to place the lamp at a consistent distance from the paper, so the experiments should be repeatable.
The first strip was exposed for 1, 2, 3 and 4 minutes. It was produced by shading parts of the paper just like exposing a test strip. The first strip shows that 1 minute is not enough and 2 minutes is too much. So I exposed a second strip to determine where between 1 and 2 minutes the correct exposure lies. The second strip is exposed in 15 seconds starting at 60 seconds. This time it is a bit more difficult to tell where the correct exposure lies, but it looks like it is around 90 seconds.
So now I know that 90 seconds is the least amount of time that it will take to produce maximum black (blue!) using the sun tan lamp. Now it is a case of producing negatives of the appropriate density to produce the required cyanotype.....
