Calibrating a Nuarc Light Integrator

[davosproject]

I have a Nuarc 40-1K. Exposures seem to vary with ambient temperature. at 20C 50 units is about 30 something minutes and that is what my curve is based on, but at 10C its much less time and the wedge is obviously underexposed with poor dmax, at 30C 50 units is about an hour long exposure and prints are overexposed. Is there anything I can do about this. I am not even shure what the light integrator is when I look inside the unit, let alone how one would calibrate it. My nuarc and printing are in the garage now so temperature is not controllable.

Any help appreciated.

David

 

[gmikol]

I don't tend to print in the summer, so I don't typically see 30C temperatures, but I don't recall seeing that much variance in the 10C to 20C range in my NL22. I'll pay a bit closer attention to ambient temperature and actual clock time of exposure.

It's also interesting that higher temperatures = longer times, I would have guessed that higher temperatures would have favored an aging bulb while cold would slow it down. So it's probably not the bulb, but rather something in the electronics?

This thread has some calibration and adjusting tips for the 26-1k, which I'm guessing is pretty close to the 40-1k:

(there was a url link here which no longer exists)

Are you letting the electronics warm up prior to use, or is it completely powered off right up until the moment you set the unit and start the exposure?

Good luck--

Greg

 

[davosproject]

Thanks for that link, I didnt turn it up when I did a google. I see now. Perhaps if I put it closer to the light it will be more accurate. I havent found it too bad except at the extremes. It could be that the shorter exposures are more contrasty than the longer exposures, even though the light units are the same. I have noticed that very long exposures seem to suffer from reciprocity faliure. I am printing with 50g/l ink in the glop, 12.5% gelatine and 2% Ammonium Dichromate and the same 100 step wedge.

David