View Full Version : AZO printers who use r-40 300 watt bulb-

27-Oct-2005, 15:52
I want to try out azo printing using the suggestions Michael Smith makes in his various articles about it, one question I have is about the hieght between the bulb and the paper- how far should the distance be? He does not state this in the articles-

"I recommend using an R40 300-watt light bulb, one with the silvered part on the neck of the bulb. The average exposure should be between 10 and 20 seconds, but fine prints can be made with exposures as short as 3 seconds and as long as 3 minutes"


Michael A.Smith
27-Oct-2005, 15:54
About 3 feet. But it can be higher or lower.

Benno Jones
27-Oct-2005, 16:00
I could only find a 150 watt bulb locally and have gotten roughly 20-30 second exposures at about 2 1/2 feet. I did buy a 300 watt bulb online and it blew out the second time I turned it on. (Yes, I was using a 300 watt fixture)

John Berry ( Roadkill )
27-Oct-2005, 17:00
Mine is just a little over 3 feet. Exposure times are 14-16 seconds.

John Kasaian
27-Oct-2005, 18:46
Here in the 'Barbie' bathroom/darkroom, we aren't allowed to drive nails or screws into the walls or ceilings, so I use a painter"s floodlight fixture----the kind with a metal reflector and a clamp, which I clamp on to a towel bar and then aim it down at a small table about 20" underneath. It works!

27-Oct-2005, 18:59
For prints in the 12X20" to 16X20" size I would place the lamp at about 36" from the printing frame. This will give very even illumination. If your largest print is 8X10 you could place the lamp at 18"-20" and get very even illumination.

In my own work I find that the R-40 300 watt bulb puts out a lot more radiation than I need. I print on AZO with a R-40 65 watt bulb, at 36" from the printing frame, and my exposures are in the 15-25 second range. Note, however, that the shadow density of my negativs is typically in the .15-25 range, whereas Michael Smith is printing Super-XX negatives, long out-dated, that has a B+F of around log 0.45 or higher, which gives a total shadow density of 0.60 and higher. This adds about two stops to base printing time.

Bottom line is this. If you use fresh film, and don't overexpose, a 65 watt or 90 watt R-40 bulb will give you more than enough radiation for exposures on AZO in the 15-25 second range, with the bulb placed at about 36" from the printing frame..

John D Gerndt
27-Oct-2005, 20:13
Ignoring the KISS principal because I hate being blinded by the white light, I built a box, 10x12 (at the top, 14 inches deep) using two 100w bulbs and two difusers toped wiht a healthy .5 inch thick glass. I lay the negs and paper on that and then a .5 inch cover glass over which I drape a towel. I then lean on the whole rig to make the pressure to keep the sandwich flat. Printing times are a consistant 20 seconds. My eyes never need re-adjusting and the sandwiching procedure is fast enough to turn out a good number of prints in an evening. Obviously, I don't do burn and dodge.


28-Oct-2005, 05:40
I've used a 120-watt R40 for a couple of years at about 2-feet above the paper for 8x10.

One caution - be sure you get a floodlight, not a spotlight. The packaging is usually almost exactly the same for the two bulbs. I made the mistake and bought the spotlight at first - it has a much narrower beam that won't cover the paper evenly.

Ben Calwell
28-Oct-2005, 06:06
Wow -- all I need for Azo is a 40-watt household bulb in a Lowe's-bought silver reflector about 2.5 feet above the negative. My average exposures are about 30 secs. to 1 minute. When I first tried Azo, I went out and bought at 300-watt bulb as suggested by many, but promptly "fried" the paper black. It was WAY too much light for my negs.