8 x 25 Watt (fluorescent tubes 450 mm) // Sylvania T8 BL368 18 Toughcoat™
Non dimmable and 4 electronic ballast are used for powering up the lamps.
set-up (as diffuse source)
This gives +/- 0,16 Watt/cm2 (for the light source)
distance between light source (see above) and contactprint
+/- 170 mm
- Did I understand well, as mentioned in Pradip and Mike’s book for Platinotype that with a ‘diffuse source’ the distance plays a more significant roll on the exposure if the distance is in steps of +/- 150 mm? (It seems in my set-up and lamps that after some tests (with 100 mm and 170 mm distance light source/contact print) there is no difference between 100 mm and 170 mm.)
The ‘problem’; to short Base Exposure Time
I’ve made test strips (Platine Arches 310 // Malde-Ware Method 2 50-50 Pt/Pd) to obtain the Base Expousre Time (Chapter 7 as per above mentioned book). I’ve used a glass rod aswell a humidity box.
The best results are the following:
What gives me an exposure time of about 2 minutes. In my feeling/opinion to ‘short’ for this time of light source (fluorescent tubes).
- Currently the distance between light source and contact print I can increase until +/- 200 mm.
- I can replace the lamps with lamps of 15 Watt each (total of 120 Watt). This wil result in a power of +/- 0,09 Watt/cm2