HID lamp and exposure times for Kallitypes

[philsweeney]

I decided to go with the HID lamp as descibed in Sandy King's article on UV light sources. Should I do a test strip (using a whole sheet not a strip) for starters?

At what point can I view the print in full light?

 

[sanking]

Phil,

Whatever system you use for evaluating exposure with AZO should work fine with kallitype. The main issue is that the paper you use to test exposure should be coated in the same way you coat the paper used for the final print. In other words, adjust the amount of sensitizer to give the same ratio for the small and large print, and try to be as consistent as possible in the way you coat.

I work with a 50 watt yellow bug light when coating, dry the sensitized paper in the dark, and turn on full room lights about 15 seconds after the print is in the developer.

However, you will not be able to judge exposure until after the print is fully processed and dry. Dry down is very significant with kallitype. And if you plan to tone the final print, as you really should for permanence, you need to also tone the test print.

 

[philsweeney]

In Sandy's article he specifies a negative at 1.8 log. Is that from UV readings? Most of my negatives are stained either ABC or pyrocat and I can measure blue channel (no UV densitometer).

 

[sanking]

In Sandy's article he specifies a negative at 1.8 log. Is that from UV readings? Most of my negatives are stained either ABC or pyrocat and I can measure blue channel (no UV densitometer).

Yes, the 1.8 DR is UV reading, or effective density range. If your ABC and Pyrocat-HD negatives read 1.5 in blue channel, add about log 0.15 for ABC and about log 0.35 for Pyrocat-HD negatives to get a effective UV printing density.

Sandy

 

[philsweeney]

I put my HID lamp in the darkroom. If after exposure (Kallitypes) I develop with the lamp on can I expect some fogging? I ask because Sandy's article recommends leaving the HID on for the entire session. But I believe for developing Kallitypes the development should start in the dark or low light. The 1000W HID is a lot of light!

 

[sanking]

Phil,

You will not get fogging once the developer hits the paper, but I suspect that there would be enough ambient light from the HID lamp to give you fogging while transfering the exposed paper from the contact printing frame to the developing tray.

BTW, the only reason I recommend leaving the lamp on for the entire printing session is because it takes about five minutes to reach peak output and just leaving it on avoids the problem as you just heat it up once. However, in your case, with the exposing lamp in the darkroom itself, it would probably be best to turn it off.

Sandy

 

[glbeas]

I put my HID lamp in the darkroom. If after exposure (Kallitypes) I develop with the lamp on can I expect some fogging? I ask because Sandy's article recommends leaving the HID on for the entire session. But I believe for developing Kallitypes the development should start in the dark or low light. The 1000W HID is a lot of light!

If it turns out that turning off the lamp is too impractical the you should make a ventilated enclosure for the lamp that has a door to be opened and closed as a shutter. Olec makes high energy lamps that operate in a similar manner, so the idea is not too original. Just be sure the materials used can handle the heat. If the lamp has a significant UV output yellow safety glasses are in order to prevent the risk of damage to your eyes from extended exposure. Plateburners I've seen that are not fliptop use curtains that pull shut during the exposure to protect the operator.

 

[sanking]

Best solution of course is to get a light integrator. A light integrator measures the actual amount of light that falls on the print and allows you to just turn a HID light on and off and get perfect exposures every time. This is the way I always used by HID light.


Sandy King

 

[philsweeney]

Perhaps in time I'll get an integrator. Are there models to avoid or prefer? I see an AGFA on ebay and it looks complicated! Also I can see calibration screws in the back and wonder how one gets calibrated if someone has messed with the calibration. What would be a reasonable price for a used one?

 

[sanking]

What I would recommend is an Olex AI 970, 111, 121 or 131, but make sure the unit comes bundled with a light sensor. These units, which are powered by direct connection to AC power, can be used as is with UV tube banks of up to around 500 watts, but for use with a HID lmap you will either need a Controlled Light Intensity Box, or a tripping relay.

The Agfa unit now for sale on ebay is really made by Olex and is same as theeir TI 985sc, but it is being sold without a light sensor. Also, in order to use this unit you would need a CLI because the TI 985sc is power wired through the CLI, not directly into an AC outlet.