New UV Box - Long exposures for Pd/Na2

Minas Stratigos · Oct 3, 2018

Hi,

i made a new UV box for 11x14 paper (Pd/na2 printing) using 8 x T8 Blacklight Fluorescent - F25T8/350BL/18in Sylvania

I get exposures more than 20m at a distance between tube and contact frame of 3.5-4 inches

any advise on what might be wrong is hugely required

Minas

Alan9940 · Oct 4, 2018

Are you printing analog or digital negatives? My UV box is made by Edward Engineered Products, but seems very similar to yours. Digital negs, for me, run about 6-7 mins. Analog negs, depending on density, can run upward to nearly 20 mins.

Minas Stratigos · Oct 4, 2018

Alan9940 said:
Are you printing analog or digital negatives? My UV box is made by Edward Engineered Products, but seems very similar to yours. Digital negs, for me, run about 6-7 mins. Analog negs, depending on density, can run upward to nearly 20 mins.

Thanks Alan, at the moment I only print a Stouffer for exposure tests and digital negatives. I get a Dmax of 1.39 at 24 minutes with my regular mix (13FO/13Pt/1Na2@5%/1or2 Tween for 6x8 inch coverage on Hahnemuhle paper)

TheFlyingCamera · Oct 4, 2018

bring the tubes closer to your frame - make it about 1.5-2 inches off the glass and you'll halve the time.

Minas Stratigos · Oct 4, 2018

TheFlyingCamera said:
bring the tubes closer to your frame - make it about 1.5-2 inches off the glass and you'll halve the time.

This is interesting, i need to se how it can be done as my box "door" is not that high but i will think of something, thanks!

Alan9940 · Oct 4, 2018

Minas Stratigos said:
Thanks Alan, at the moment I only print a Stouffer for exposure tests and digital negatives. I get a Dmax of 1.39 at 24 minutes with my regular mix (13FO/13Pt/1Na2@5%/1or2 Tween for 6x8 inch coverage on Hahnemuhle paper)

FWIW, my drop count for a 5x7 is 15FO/12Pd/3Na2@5%/1or2 Tween for HPR. But, I didn't look closely enough at your mix before; you're printing pure Platinum. Therefore, your exposures will definitely be longer than mine, at least, in my own experience with pt.

Mainecoonmaniac · Oct 4, 2018

I built one with tubes from Petco. They're actinic tubes used for aquariums. My exposure time for cyanotypes, Ziatypes and salt prints are about 7 mins.
https://premiumaquatics.com/product...er-actinic-blue-vho-t12-fluorescent-bulb.html

nmp · Oct 4, 2018

Minas Stratigos said:
This is interesting, i need to se how it can be done as my box "door" is not that high but i will think of something, thanks!

Slide a thick book underneath.

nmp · Oct 4, 2018

Mainecoonmaniac said:
I built one with tubes from Petco. They're actinic tubes used for aquariums. My exposure time for cyanotypes, Ziatypes and salt prints are about 7 mins.
https://premiumaquatics.com/product...er-actinic-blue-vho-t12-fluorescent-bulb.html

7 mins for salt prints....that would be wonderful....I have to cook for 30 mins in my gizmo.

Mainecoonmaniac · Oct 4, 2018

nmp said:
7 mins for salt prints....that would be wonderful....I have to cook for 30 mins in my gizmo.

What type of light source are you using?

Minas Stratigos · Oct 4, 2018

Alan9940 said:
FWIW, my drop count for a 5x7 is 15FO/12Pd/3Na2@5%/1or2 Tween for HPR. But, I didn't look closely enough at your mix before; you're printing pure Platinum. Therefore, your exposures will definitely be longer than mine, at least, in my own experience with pt.

its my mistake, I print Pd, sorry

Alan9940 · Oct 4, 2018

Minas Stratigos said:
its my mistake, I print Pd, sorry

Ah, OK, I was wondering because I always heard that pt and Na2 shouldn't be used together. Out of interest, I just measured my UV box; the tubes sit about 2 1/2" above the frame.

nmp · Oct 4, 2018

Mainecoonmaniac said:
What type of light source are you using?

18 of these (https://www.amazon.com/Satco-S7277-...ements=p_n_feature_four_browse-bin:6105694011) on 12x16 area. I keep about 6" distance which could be shortened probably. I was worried about the heat it generates which I have alleviated somewhat by installing an exhaust fan recently.

Mainecoonmaniac · Oct 4, 2018

I think Minas, the OP is also using black light which I'm guessing requires long exposure times. To shorten the time, you may have to switch to a light source other than black light. I mentioned earlier that actinic tubes for aquariums may shorten your exposure time.

nmp · Oct 4, 2018

Mainecoonmaniac said:
I think Minas, the OP is also using black light which I'm guessing requires long exposure times. To shorten the time, you may have to switch to a light source other than black light. I mentioned earlier that actinic tubes for aquariums may shorten your exposure time.

May be next go around I'll use those. Looks like your tubes are 48" long. Is that how big your box is?

Minas Stratigos · Oct 4, 2018

Mainecoonmaniac said:
I think Minas, the OP is also using black light which I'm guessing requires long exposure times. To shorten the time, you may have to switch to a light source other than black light. I mentioned earlier that actinic tubes for aquariums may shorten your exposure time.

I need to see if they come in 18inches

Mainecoonmaniac · Oct 4, 2018

nmp said:
May be next go around I'll use those. Looks like your tubes are 48" long. Is that how big your box is?

My tubes are 24" long and my box is 20"x25. I have 7 tubes. They get a bit warm in the summer. I'm going to install a fan it to keep it cool.

nmp · Oct 5, 2018

Mainecoonmaniac said:
My tubes are 24" long and my box is 20"x25. I have 7 tubes. They get a bit warm in the summer. I'm going to install a fan it to keep it cool.

Thanks.

Minas Stratigos · Oct 7, 2018

Unfor

TheFlyingCamera said:
bring the tubes closer to your frame - make it about 1.5-2 inches off the glass and you'll halve the time.

I lifted the contact frame to a distance of approx 2 inches from the tubes. Still my exposure is between 24-30 minutes.

TheFlyingCamera · Oct 9, 2018

Minas Stratigos said:
Unfor

I lifted the contact frame to a distance of approx 2 inches from the tubes. Still my exposure is between 24-30 minutes.

Try getting them 1 inch from the tubes. Also, how far apart are your tubes?

Minas Stratigos · Oct 9, 2018

TheFlyingCamera said:
Try getting them 1 inch from the tubes. Also, how far apart are your tubes?

tubes are half inch apart so i do not think i can go closer than that. I ordered a different ballast to test and make sure that this does not cause troubles (although i purchased before the suggested ballast from the seller)

Vaughn · Oct 10, 2018

Alan9940 said:
Ah, OK, I was wondering because I always heard that pt and Na2 shouldn't be used together. ...

You are correct -- using Na2 with Pt is a waste of Na2. It does not act as a contrast agent when used with Pt.

Do not be too surprised if moving the contact printing frame closer to the bulbs does result in significantly faster exposure time. The "square of the distance" rule does not apply here (diffuse light source).

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