Led lights

[deanwork]

Is anyone using LED light source for contact printing on alternative process from OHP negatives?

[disneytoy]

I'm not, but you should research the specific process and make sure you are producing the correct UV frequency.  I've printed large digital negatives 40" wide on Pictorico PHP and they use a series of sodium vapor lights. Produce a lot of full spectrum UV. I think LEDs are far more narrow.

Good luck!

Max

[Ernst Dinkla]

Based on my silkscreen background I can write that Max is correct. The sensitivity of the emulsion has to correspond with the lamp's UV frequency. LED's are used in curing system of UV inks though (fast powering on/of on passing sheets) so it should possible. There however it is not important to have a point source light, to get the sharpest copy in contact printing a point source is recommended and of course a vacuum frame. Of the last the transmittance of the glass counts too. Usual UV lamps in silkscreen screen copying are metal halide 3-5K watt, smaller less pro use high pressure sodium/mercury lamps but I doubt they still can be used due to environmental rules.


Met vriendelijke groet, Ernst

http://www.pigment-print.com/spectralplots/spectrumviz_1.htm
March 2017 update, 750+ inkjet media white spectral plots

[donbga]

Is anyone using LED light source for contact printing on alternative process from OHP negatives?

Yes there are some folks out there using narrow wave length LEDs to print alternative processes.

Take a look at this link for a thorough rigorous discussion about design and using UV emitting LEDS:

LED UV Printer for Alternative Processes

Atlanta Light Bulb is a good local supplier for your if you want to use UV-BL fluorescent tubes with 350-365 nm output which is a good general purpose tube to use for alternative processes especially since it is a 40W tube.

BL-UV GE F40BL

Check the file section on Sandy King's Carbon Printing Yahoo Forum for more info.

Don Bryant

[deanwork]

I was referring to the light weight roll out variety that are available in uv spectrum now. Someone is using them with very short exposure times for platinum and there is a video on how to make a very inexpensive unit. I used to use a big super heavy bank of uv fluorescent tubes and my exposure times were often 20 minutes. His with OHP film are  between 6-11 minutes. No heat, little energy used. You can position them as close as  3 or 4 inches to the film.

The grow light led tubes would certainly work as well just harder to construct a box for. Some of the best alternative process negs from OHP film are quite thin, also helping out the exposure situation.

Great video on how to make the bank cheaply. I have the vacuum frame already.

http://www.largeformatphotography.info/forum/showthread.php?122508-LED-UV-Light-Box-Build-Your-Own-for-Under-150

Lots of people have copied his design and are using them now for all kinds of processes, including silk screen.

john




http://www.largeformatphotography.info/forum/showthread.php?122508-LED-UV-Light-Box-Build-Your-Own-for-Under-150

[donbga]

I was referring to the light weight roll out variety that are available in uv spectrum now. Someone is using them with very short exposure times for platinum and there is a video on how to make a very inexpensive unit. I used to use a big super heavy bank of uv fluorescent tubes and my exposure times were often 20 minutes. His with OHP film are  between 6-11 minutes. No heat, little energy used. You can position them as close as  3 or 4 inches to the film.

The grow light led tubes would certainly work as well just harder to construct a box for. Some of the best alternative process negs from OHP film are quite thin, also helping out the exposure situation.

Great video on how to make the bank cheaply. I have the vacuum frame already.

http://www.largeformatphotography.info/forum/showthread.php?122508-LED-UV-Light-Box-Build-Your-Own-for-Under-150

Lots of people have copied his design and are using them now for all kinds of processes, including silk screen.

john




http://www.largeformatphotography.info/forum/showthread.php?122508-LED-UV-Light-Box-Build-Your-Own-for-Under-150

Did you peruse the entire thread? Sandy King has reported that the LEDs aren't reliable after a short period of use. If you want really short exposures for alt. processes you need power - watts, like those found in the legacy graphic arts equipment used to burn printing plates. Something on the order of 5000 watts like those manufactured by NuArc and others. Also check out Amerigraph plate burners. This used one went for a song:

Used Amerigraph

The ULF-28 is a rocking unit, not inexpensive though:

ULF-28

And the nice thing is they can be used to burn plates for photogravure printing.

Don Bryant
 

[Ernst Dinkla]

Did you peruse the entire thread? Sandy King has reported that the LEDs aren't reliable after a short period of use. If you want really short exposures for alt. processes you need power - watts, like those found in the legacy graphic arts equipment used to burn printing plates. Something on the order of 5000 watts like those manufactured by NuArc and others. Also check out Amerigraph plate burners. This used one went for a song:

Used Amerigraph

The ULF-28 is a rocking unit, not inexpensive though:

ULF-28

And the nice thing is they can be used to burn plates for photogravure printing.

Don Bryant

Well I have an Akticop 5000 that is obsolete now. Needs a new lamp but that will not be expensive.

Another one including a vacuum frame;
http://drukwerkindemarge.org/zeefdruk-belichtingsraam-te-koop/
350 Euros

In short, check the secondhand silkscreen units and preferably the fast power up units, mine is a slow one.


Met vriendelijke groet, Ernst

http://www.pigment-print.com/spectralplots/spectrumviz_1.htm
March 2017 update, 750+ inkjet media white spectral plots

[deanwork]

Thanks Ernst

yea I guess the deal with leds is you have to replace them every couple of years. I'm totally fine with 20 minute exposures and replacing the lights. What worries me is the potential inconsistency in exposure times as the bulbs weaken. I think the led grow lights would be more reliable but then you are using tubes again.
I was primarily attraced to the small footprint of the roll out lights. I'll have to contact that guy to see exactly how "unreliable" they are.

Three is no way in hell I would bring one of these monster silkscreen units into my studio. I'll build another daylight fluorescent tube box before I'd do that.

c
Well I have an Akticop 5000 that is obsolete now. Needs a new lamp but that will not be expensive. C

Another one including a vacuum frame;
http://drukwerkindemarge.org/zeefdruk-belichtingsraam-te-koop/
350 Euros

In short, check the secondhand silkscreen units and preferably the fast power up units, mine is a slow one.


Met vriendelijke groet, Ernst

http://www.pigment-print.com/spectralplots/spectrumviz_1.htm
March 2017 update, 750+ inkjet media white spectral plots

[deanwork]

I'm taking what Sandy said with a grain of salt. First of all she did a test where she mixed the led lights in with traditional fluorescent tubes and later complained that they leds lost some of their power. Well, the heat of the tubes right beside the uv bulbs could have done that alone. Another thing is she is using these boxes regularly for a ton of work. A lot of us are going to be using the lights like once a week at the most. I would be more than happy with a box like this lasting me a couple of years which at that time I could roll in a newer more improved uv led arra y. I'm going ahead with Eric's model and make one for myself. I just don't the downside for the cost of making it and the long term flexibility.

john

Did you peruse the entire thread? Sandy King has reported that the LEDs aren't reliable after a short period of use.

[donbga]

I'm taking what Sandy said with a grain of salt. First of all she did a test where she mixed the led lights in with traditional fluorescent tubes and later complained that they leds lost some of their power. Well, the heat of the tubes right beside the uv bulbs could have done that alone. Another thing is she is using these boxes regularly for a ton of work. A lot of us are going to be using the lights like once a week at the most. I would be more than happy with a box like this lasting me a couple of years which at that time I could roll in a newer more improved uv led arra y. I'm going ahead with Eric's model and make one for myself. I just don't the downside for the cost of making it and the long term flexibility.

john

Did you peruse the entire thread? Sandy King has reported that the LEDs aren't reliable after a short period of use.

FYI,

Sandy is a he not a she. He has written more about the LEDs on his Carbon Printing forum. According to his use they were not always long lived.

Sandy King Photography

Just for the record Sandy is one of the preeminent Alternative Process Printers in the US and is internationally recognized for his research of various aspects related to Alt. Processes including various light sources, integrators, film developers and large format cameras optimized for alt. processes. He is a noted author of many articles on alternative process printing and books specifically about carbon process printing. His photography work has been published in many magazines and has been included in several international exhibits featuring alternative process prints.

He  did extensive work with Mark Nelson helping test and refine Precision Digital Negatives and has helped refine the use of Quad Tone RIP with monochrome inksets for digital negatives.

And he lives just right up I-85 in S.C. so he is occasionally available for one on one workshops in his home near Greenville.

Don

[deanwork]

Cool. I was confusing him with another Sandy who is an alternative process specialist. I'll read more on his opinions of led lights.
 But I just have to say I do believe the train has left the station when it comes to the future of led uv lights. We just came back from a walk in our dark neighborhood. I pulled out my new tiny micro mag light flashlight. Turned it on for the first time and with the power of two little aa batteries it blasted a blinding beam at least equal to my car headlights. Led is here big time and everything else is on the way out.
 


quote author=donbga link=topic=117290.msg971232#msg971232 date=1491696924]
FYI,

Sandy is a he not a she. He has written more about the LEDs on his Carbon Printing forum. According to his use they were not always long lived.

Sandy King Photography

Just for the record Sandy is one of the preeminent Alternative Process Printers in the US and is internationally recognized for his research of various aspects related to Alt. Processes including various light sources, integrators, film developers and large format cameras optimized for alt. processes. He is a noted author of many articles on alternative process printing and books specifically about carbon process printing. His photography work has been published in many magazines and has been included in several international exhibits featuring alternative process prints.

He  did extensive work with Mark Nelson helping test and refine Precision Digital Negatives and has helped refine the use of Quad Tone RIP with monochrome inksets for digital negatives.

And he lives just right up I-85 in S.C. so he is occasionally available for one on one workshops in his home near Greenville.

Don
[/quote]

[stevehayes]

Hi Deanwork! A the moment, I'm trying to build my exposure unit based on UV LEDs. I use non-waterproof 16ft length of "3528 SMD" blacklight LEDs and many other accessories from ukled.co.uk. The main thing I did, I cut the long LED string into shorter strings, soldered wires to them, connected them in parallel, and attached them to an aluminum plate and after this I assembled a cardboard unit. It's not done yet but I hope it will work because I put a lot of time and effort into it.