Fluorescent Grow Light Bulbs for alternative printing.

[gary892]

I have a light fixture for alternative printing and I am wondering if these Fluorescent tube are of the correct wavelength?

8-Pack AgroMax 4 Foot (45.75") Pure PAR Veg T5 Fluorescent Grow Light Bulbs - (8) F54T5HO Bulbs
by HTGSupply

These are from Amazon.

My light fixture is designed for the T5 size of Fluorescent tubes.

Thanks in advance.

Gary

[Vaughn]

Google the company that make the lamps -- they usually will have the wave lengths graphed out.

PS. Most units I have worked with use the BL tubes...cheaper and as effective (if not more) than the BLB.

Edited to add. I wish Agromax would have included the spectrum output of their lights on their site. I am hesitant to recommend the AgroMax Pure UV T5 Bulb – 4 Foot tube. Besides UVA (320-400), it is designed to emit UVB (280-320), which alt processes in general are sensitive to, but 1) it is damaging to skin and eyes and 2) if you are using a contact printing frame with glass, most of that UVB will be blocked by the glass*....so one might be exposing oneself to damaging rays that aren't helping much.

The AgroMax Pure PAR Veg T5 Fluorescent Grow Light Bulbs seem to be a better choice of the two, depending what its output really is. BL tubes peak at 350.

* 95% as per Sandy King...https://sandykingphotography.com/resources/technical-writing/uv-light-sources-for-printing

[NHE]

I can’t speak to that specific bulb as to wether it will work or not, but looking at the spectrum it seems the wavelengths may be too long as there isn’t much output below 400nm. I also use a grow light as my exposure unit. There are two bulbs that’s I know work, at least for cyanotype and pt/pd. They are:

1. AgroMax Pure UV T5 Bulb – 4 Foot
These have an emission peak at around 365nm with a pretty narrow spectrum. They work well if you are using in camera negatives, however they tend to produce long exposure times (30mins for a cyanotype) when using digital negatives printed on pictorico as it blocks a significant portion of the up output.

2. Eye Hortilux Power VEG 420
These have an emission peak around 420nm. These work well for both in camera and digital negatives on pictorico and gives very fast exposure times, in the 2-4 minute range for pt/pd and 6-8 for cyanotype from a distance of around 6 inches. The pt/pd exposure times are probably too fast and I am considering moving the light further as I think I loose shadow contrast with an exposure that short.

I hope this helps.

Nick

[gary892]

I can’t speak to that specific bulb as to wether it will work or not, but looking at the spectrum it seems the wavelengths may be too long as there isn’t much output below 400nm. I also use a grow light as my exposure unit. There are two bulbs that’s I know work, at least for cyanotype and pt/pd. They are:

1. AgroMax Pure UV T5 Bulb – 4 Foot
These have an emission peak at around 365nm with a pretty narrow spectrum. They work well if you are using in camera negatives, however they tend to produce long exposure times (30mins for a cyanotype) when using digital negatives printed on pictorico as it blocks a significant portion of the up output.

2. Eye Hortilux Power VEG 420
These have an emission peak around 420nm. These work well for both in camera and digital negatives on pictorico and gives very fast exposure times, in the 2-4 minute range for pt/pd and 6-8 for cyanotype from a distance of around 6 inches. The pt/pd exposure times are probably too fast and I am considering moving the light further as I think I loose shadow contrast with an exposure that short.

I hope this helps.

Nick

Nick, thank you for the very informed response.

I was researching the AgroMax Pure UV T5 Bulb – 4 Foot and that is what prompted my question.

Thanks again
Gary

[gary892]

Thank you Vaughn and Nick for your responses.

Gary

[NHE]

After some time printing I feel I should update my opinion of these bulbs and that I can not really recommend either of these bulbs. The 420nm bulb tends to fog with even slight over exposure, you can work around it with digital negatives but even so the results can be inconsistent. The pure UV bulb works much better however the UV output is mostly in a region which is not useful and it tends to produce a large amount of ozone during exposure which in my small darkroom is not a good thing.
I have since moved on to LEDs which produce light in the 365-370nm wavelength with good results.

[Jim Noel]

I'm with VAughn - BL bulbs seem to work best for the various alt processes I utilize.

[Lisa K]

NHE - can you please be specific as to what LED bulbs you have moved on to using that you feel have given you the results you are looking for, how many, and at what distance from your support you have placed them? Also, what exposure time have you been using? I have four fluorescent fixtures holding 2 bulbs each of F-40T12BL 40 Watt - T12 tubes (they are 48 inches). I have them about 5 inches away from the support. I make a digital negative with either Pictorico or Fixxons film and expose the cyanotype for 30 minutes. I am hoping to find a better "LED" bulb that makes my exposure go quicker.

[William Whitaker]

NHE - can you please be specific as to what LED bulbs you have moved on to using that you feel have given you the results you are looking for, how many, and at what distance from your support you have placed them? Also, what exposure time have you been using? I have four fluorescent fixtures holding 2 bulbs each of F-40T12BL 40 Watt - T12 tubes (they are 48 inches). I have them about 5 inches away from the support. I make a digital negative with either Pictorico or Fixxons film and expose the cyanotype for 30 minutes. I am hoping to find a better "LED" bulb that makes my exposure go quicker.

+1, please.

[martiansea]

NHE - can you please be specific as to what LED bulbs you have moved on to using that you feel have given you the results you are looking for, how many, and at what distance from your support you have placed them? Also, what exposure time have you been using? I have four fluorescent fixtures holding 2 bulbs each of F-40T12BL 40 Watt - T12 tubes (they are 48 inches). I have them about 5 inches away from the support. I make a digital negative with either Pictorico or Fixxons film and expose the cyanotype for 30 minutes. I am hoping to find a better "LED" bulb that makes my exposure go quicker.
I use a 20W UV LED with a wavelength in the ~390nm range (I don't remember which it was exactly, like not under 380 and definitely not over 395, in any case 400nm should be considered a hard cutoff, absolutely nothing over that). It can expose an 8x10 cyanotype on an average of around 10-12 minutes at a distance of approximately 12", most other processes are much faster, well under 10 minutes for Argyrotype, about 5-6 minutes for gum prints. Did a platinum last night in 5 minutes...

The LED is mounted to a large heatsink and it is powered by a 20w LED driver module that runs directly from AC mains. I control it with a standard GraLab darkroom timer. It has been very reliable for me for about 3 years now. No one should be using fluorescents in this day and age.

[NHE]

NHE - can you please be specific as to what LED bulbs you have moved on to using that you feel have given you the results you are looking for, how many, and at what distance from your support you have placed them? Also, what exposure time have you been using? I have four fluorescent fixtures holding 2 bulbs each of F-40T12BL 40 Watt - T12 tubes (they are 48 inches). I have them about 5 inches away from the support. I make a digital negative with either Pictorico or Fixxons film and expose the cyanotype for 30 minutes. I am hoping to find a better "LED" bulb that makes my exposure go quicker.


+1, please.

I use this led strip: https://store.waveformlighting.com/products/real-uv-led-strip-lights?variant=12527605252198

I cut and soldered a 5m strip (of the 365nm) so the exposure area would cover my 11x14 printing frame. The strips come with adhesive so I just stuck them to a plywood board I had, in retrospect an aluminum sheet would have been better as they didn’t stick all that well. The LEDs get warm but not hot enough that they need a heat sink.

Exposure distance is approximately 2in as that was the closest distance where the beam spread appeared even. As to exposure time, a palladium print will get to maximum density in around 2min through an unexposed area of film and around 5min through a blank area of pictorico. I don’t typically print cyanotypes but if I remember correctly the exposure time would be in the 10-15 minute range.

I have focused more on using film lately, but my longest exposure has been around 60min. That was to get detail in an area of snow with a density of log 2.8-3.0. The LEDs are expensive so it was a tough decision, but it has been worth it when printing negatives with very dense highlights.

[martiansea]

I use this led strip: https://store.waveformlighting.com/products/real-uv-led-strip-lights?variant=12527605252198

I cut and soldered a 5m strip (of the 365nm) so the exposure area would cover my 11x14 printing frame. The strips come with adhesive so I just stuck them to a plywood board I had, in retrospect an aluminum sheet would have been better as they didn’t stick all that well. The LEDs get warm but not hot enough that they need a heat sink.

Exposure distance is approximately 2in as that was the closest distance where the beam spread appeared even. As to exposure time, a palladium print will get to maximum density in around 2min through an unexposed area of film and around 5min through a blank area of pictorico. I don’t typically print cyanotypes but if I remember correctly the exposure time would be in the 10-15 minute range.

I have focused more on using film lately, but my longest exposure has been around 60min. That was to get detail in an area of snow with a density of log 2.8-3.0. The LEDs are expensive so it was a tough decision, but it has been worth it when printing negatives with very dense highlights.

The 20W LED I use cost 1/10 this price and gets the same printing time at a distance of 12 inches. (I'm saying just the LED without the other equipment)

[martiansea]

I've gone back and found the details about my LED. I bought it from Taobao in 2018 (I was in China at the time) for 62RMB; less than $9. After getting back to the US, I ordered a Chanzon 20w 600mA constant current LED driver from Amazon for $8.81 and a cheap heatsink from Amazon for $14.99 (I wouldn't buy this particular heatsink again, the quality wasn't good. Better to order one from HeatsinkUSA, still inexpensive). A suitable AC power cord can be gotten for less than $5. All told, this package was put together for well under $40, and nothing else is necessary to use it for printing apart from figuring out a means to hang it above your work surface. At the moment, I have mine in my oven. It sits on the top rack and the work I'm printing sits on the bottom rack. If I need to get them closer together for some reason, I need only change the position of the rack. This sounds maybe crazy, but it works like a charm and the oven door does an excellent job of blocking the UV light. Of course I have to be careful not to forget it in there if I'm going to make a pizza! :eek:

The Taobao listing for my LED said it is in the 380-385nm wavelength range. I'm getting very good printing results with this range; I printed all the pieces you see here with this LED: https://entropyandchaos.com/?portfolio=surrogate-activities
You can get an equivalent 385nm 20W LED from Amazon for $22.99, more than twice the price as from Taobao, but it's still dirt cheap compared to all the prefab UV printing units I see out there. One of these 20w LEDs is plenty coverage for an 8x10, and it can do 11x14 too with a little bit more distance and maybe a couple more minutes printing time. I haven't tried to do larger than 11x14 with it yet.