I just got my vacuum exposure unit working and I want to try exposing using the sun (since the space has huge east facing windows.) I use Manoukian ZERO-IN Speedcure blue as my emulsion. Have any of you ever used this combination? If so, do you have a recommendation for a "starting point time?" I assume location would have an effect on the exposure time, so I'm in Germany.
I don't know the emulsion - do you add diazo? or is it SBQ/pure photopolymer?
A diazo emulsion, or dual cure is best, as it is less sensitive to light, so gives you enough time. At my location (50th parallel Vancouver island) in summer I have 80 seconds on yellow, 45 on white mesh. IN winter it changes a lot, the exposures can be a lot longer.
if your emulsion is a fast polymer type (no diazo) your times will be half or even less - you have to be very careful you don't pre- or overexpose, as even weak ambient light will expose the fast emulsions.
Do some tests drag a black card across in 10 second intervals. Note the position of the sun and overcast/weather. If you can see a shadow, you usually have enough light for a solar exposure