Metal Halide lamps for printing

lucille · Aug 10, 2011

Hi, right now I just use the sun to print stuff like cyanotypes and such, but I was wanting to start doing more printing, and different methods.. like carbon prints mainly. So I was considering using a metal halide lamp from a hydroponics store.

My question is are the ones with horizontal bulbs suitable? Because they have complete units with a reflector and holding the bulb horizontal and ballast. Or is it better to have a reflector that holds the light perpendicular to the print?

The bulb I was considering was the 400W 'blue' one by eye hortilux (MT400D/HOR/HTL - BLUE). The blue seemed to have more light in the UV-blue range.

Is a 400 watt enough since I mostly contact print 4x5-5x7 negatives?
Does anyone know if this bulb is a good choice?

Thanks!

Robert Hall · Aug 11, 2011

It looks as if you have enough in the UV spectrum but I can't say anything about intensity as I've never used one. One think you really want, however, is a nice even light. It might be worth a try.

I have an 1800 watt setup and my print times are around 6 minutes for an 8x10.

I hope that helps.

polyglot · Aug 11, 2011

The discharge produces crazy amounts of UV, but they carefully put a glass tube around it to cut as much UV as possible, for safety reasons. A bare HID lamp with no UV barrier will give you sunburn, conjunctivitis and all sorts of other issues in just a few minutes. The big "mogul base" glass tubes are (I think) fairly effective UV absorbers, plus the large outer tube acts as an insulating layer so you don't want to just smash it off because the inner envelope probably won't be able to get up to temperature any more.

You might be better off looking for a bare bulb that is designed to be installed in a larger enclosure where the enclosure is responsible for UV blocking. The drawback there though is that the larger enclosure is also responsible for containing explosions, which is how about 5% (more for the cheap chinese ones) of HID bulbs end their life. You really don't want to have one go off in your darkroom without some protection around it; there will be shards of molten quartz and metal raining down with more than enough energy to set anything papery (or human) alight that it lands on.

You may be able to get a bulb with an all-quartz safety shield, which would have significant UV output.

lucille · Aug 11, 2011

Wow, your description of the hazards makes it not seem worth it, uh, I had heard that metal halide was a good option, but maybe I should just stick to fluorescent tubes.

polyglot · Aug 11, 2011

HID is an excellent option, you just need to have them in a proper enclosure or get one with a quartz envelope. I have some MH floodlights (250W) with what I think are ED28 bases (like a screw-in lightbulb but huge); the bulbs themselves have a thin glass envelope for safety and that blocks most but not all of the UV - they can still cause itchy eyes at close range.

If you bought a high quality T6 globe with quartz envelope (Dead Link Removed), that would give you massive quantities of UV. Just be sure you replace it as soon as it shows any sign of cycling instead of staying on solidly; that's the end-of-life indication. With a good quality (Phillips or GE) globe that you replace as soon as it starts cycling, your chances of an explosion are probably not worth worrying about, even if they say T6 is for use in "enclosed fixtures only".

The other thing to consider if you're going to the expense of having a HID ballast etc, is that Mercury Vapour lamps produce more UV than Metal Halide, which are generally designed for a whitish light. In fact, it seems you can buy low pressure Hg lamps designed to produce 185nm and 253nm UV for the purpose of germicide and exposing litho plates, so they ought to be pretty perfect for carbon printing; example. You probably want the non-ozone-generating versions since ozone is a very strong oxidiser. And you want good (probably acrylic) shielding of your exposure box, or you will get skin and eye damage in short order.

jp498 · Aug 11, 2011

I've got a metal halide indoor light (pictured in the link) for lighting a gym or warehouse, and it has a 400w bulb and does a great job with alt process stuff.

Dead Link Removed

phritz phantom · Aug 11, 2011

i came across this today: http://www.conrad.at/ce/de/product/590867/UV-LEUCHTMITTEL-R7S-250-W;jsessionid=82EFB87738E521381C31297164A9AEF6.ASTPCCP1

a r7s-socket uv-lamp, which should fit into a cheap flood light (not closing the glass cover it came with, to not add any uv-filtering, i guess). it costs about $20 and i'll pick one up soon and see how it prints.
there's a data sheet available (in english too), but there isn't much info apart from "emits strong uv-light in close proximity. take care".
http://www.produktinfo.conrad.com/datenblaetter/575000-599999/590867-an-01-ml-UV_Leuchtmittel_R_7_s_250W_de_en_fr_es.pdf

lucille · Aug 11, 2011

The bulb I had been originally considering had an outer envelope of borosilicate glass (inner quartz), which cuts off below 330nm, is the radiation above 330nm not enough to adequately expose a print? Because that seems a good mix of some UV, as well as safety from the shorter UV radiation.

polyglot · Aug 11, 2011

phritz phantom said:
i came across this today: http://www.conrad.at/ce/de/product/590867/UV-LEUCHTMITTEL-R7S-250-W;jsessionid=82EFB87738E521381C31297164A9AEF6.ASTPCCP1

a r7s-socket uv-lamp, which should fit into a cheap flood light (not closing the glass cover it came with, to not add any uv-filtering, i guess). it costs about $20 and i'll pick one up soon and see how it prints.
there's a data sheet available (in english too), but there isn't much info apart from "emits strong uv-light in close proximity. take care".
http://www.produktinfo.conrad.com/datenblaetter/575000-599999/590867-an-01-ml-UV_Leuchtmittel_R_7_s_250W_de_en_fr_es.pdf

That would work excellently. It's also hazardous of course, but we *are* trying to generate UV here. Clear acrylic (aka lexan or perspex) will block all the dangerous stuff.

Only drawback is the rated life is 500 hours.

DPVisions · Aug 12, 2011

Any light the emits in the UV-A, 315nm - 400nm, range should work very well for alternative processes. Moving into the UV-B range may give you additional benefit with shorter exposures but is not worth the risk associated with UV-B and/ or UV-C spectrums. UV-A specturm is not something to fear if respected and and you do not look directly into the light for extended periods of time.

A metal halide @ 400W and with a Kelvin temperature above 6500K should be sufficient for contact printing, the hight the wattage the further the lightsource can be away from the print.

For those that are interested in reading more details on suitable light sources for contact/alt processing printing I definately recommend taking a look at Sandy Kings excellent article at the Unblinking Eye - http://unblinkingeye.com/Articles/Light/light.html

Cheers,
David

Herzeleid · Aug 12, 2011

I would not want to hijack this thread in my favor but I am curious about one thing. I was planning to build a light source for alternative processes, but I just happen to have a metal halide with the casing sitting around.
The bulb and the ballast is 150watts. It is a philips MHN-TD, the bulb has a quartz casing. I checked the spectrum it shows it produces some UV in usable range. Do you think that is feasible to use after removing the glass from the casing or should I not bother myself and go build a device.

Loris Medici · Aug 12, 2011

Serdar, that lamp's spectral power distribution chart look useless (for alt-processes) to me. You need something that puts most of the energy around 350 - 370nm... What process do you have in mind? Why not using UVBL tubes? (Istanbul'da var, fiyatlar uygun...)

EDIT: See Philips lamps with "/10" suffix in their codes. The codes with "R" indicates each lamp has it's own reflector, you'll get higher efficiency with those... See Dead Link Removed (Actinic BL bulbs) in the Philips catalogue. (online, Turkish...)

See that particular lamp's spectral power distribution chart below:

Herzeleid · Aug 12, 2011

Loris Medici said:
Serdar, that lamp's spectral power distribution chart look useless (for alt-processes) to me. You need something that puts most of the energy around 350 - 370nm... What process do you have in mind? Why not using UVBL tubes? (Istanbul'da var, fiyatlar uygun...)

Well for starters cyanotype, may be van dyke. I planned to build something with uv bulbs but I haven't had the chance yet. Because I had no experience with the processes yet, I thought may be if that MH bulb would work, I can use it to start some experimenting. (uygun olursa birşeyler danışmak isterim)

ian t · Sep 29, 2018

Hi,
Would this 1000 watt metal halide bulb be good for alt process printing? I'm embarking on Salt and Carbon prints - https://www.amazon.ca/Philips-32150...51730&sr=8-20&keywords=1000+watt+metal+halide

Many thanks,

Ian

Vaughn · Sep 30, 2018

This is close to what I use: https://eyelighting.com/hid-lamps/mercury

The 750W self-ballasted mercury vapor lamps at the bottom of the document. What I use, they do not have...the closest is the very last two in the list. Mine are for regular 120V line voltage. The advantage is no need to buy and set up a ballast for the lamp.

Below is the box, lamp, and the set-up I use. The lamp is suspended from the wood -- I use chairs, etc to hold it up. The contact frame is on the floor (about a foot to 16" up to the bulb) with a fan blowing across the glass of the contact frame to keep it cool. I have three of these for workshops (very portable).

Vaughn · Sep 30, 2018

ian t said:
Hi,
Would this 1000 watt metal halide bulb be good for alt process printing? I'm embarking on Salt and Carbon prints - https://www.amazon.ca/Philips-32150...51730&sr=8-20&keywords=1000+watt+metal+halideIan

This type of lamp usually requires a ballast, but I could not see where it mentioned which type.

BJ68 · Oct 1, 2018

For cyanotype workshops (with children) I use a UV cluster made of 5 Osram Ultra-Vitalux lamps
https://www.osram.com/pia/ecat/ULTR...PS01_1028569/PP_EUROPE_Europe_eCat/ZMP_60829/
which are installed at a "Lochblech" (perforated metal plate) with porcelain E27 lamp holders.

Exposure times are 5 min (safe side) or less and it seems that the UV makes no sunburn at the skin, because a few kids and I (as the first one) made a print of our hand as test.

Two disadvantages:

a) The lamps have to be always on, even it the device is not used...
b) It consumes 1.5 kWh for every hour.

Plus the floor is heated to about 30°C if the device is installed about 60 cm above the ground.

Bj68

AgX · Oct 1, 2018

BJ68 said:
a) The lamps have to be always on, even if the device is not used...

What do you mean by that?

BJ68 said:
....it seems that the UV makes no sunburn at the skin, because a few kids and I (as the first one) made a print of our hand as test.

"In case of improper use, UV radiation may lead to sunburn and conjunctivitis. Not approved for use on persons according to the new edition of EN 60335-2-27"
I then wonder why they are proposed by the manufacturer as to be used in a terrarium.

Vaughn · Oct 1, 2018

Interesting bulbs! Five 300W bulbs for 1500W total -- the 5 minute exposure times and the heat generated is not surprizing! A smaller version of what I use (I use a single 750W bulb). I would still take precautions with UV exposure to unprotected eyes.

AgX -- they are self-ballasted lamps. If turned off, some time is needed before it will turn on again. Plus there is a long warm-up time. Without a UV meter, the lamps must be left on in order for timed exposures to be consistant.

AgX · Oct 1, 2018

Those are hybrid lamps, they seemingly include a plain lighting filament as current limiter, thus there is no need for a special power supply.

Vaughn · Oct 1, 2018

AgX -- you might be right. They seem similar to what I use, but the lifespans are very different. The merc vapor self ballasted lamps are rated to 12000hrs, and the Osram is rated to only 1000 hours.

AgX · Oct 1, 2018

1000h = typical longevity of an incandescant lamp

With such lamp one has to weigh the low economics for our use against the otherwise (power source) upcoming initial costs.

DonF · Oct 1, 2018

I use one of these for salt prints and sunning silver nitrate for wet plate:

https://www.amazon.com/gp/product/B018C71QHI/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1

The lamp will fully expose a salt print in 3 minutes or less at 24 inches. It runs cool and is safer than short wave UV bulbs.

Don

Vaughn · Oct 1, 2018

Nice little units, Don. With a wavelength range of 395nm to 400nm, it should be useful, though narrow.

mgatrn · Jun 19, 2019

Do you get nice deep blues and crisp detail with that setup?
Also, do you know what wavelength the lamp luminates at?
I believe 365nm is the sweet spot for sunlight (which I find is excellent for cyanotypes).

I bought a BL fluoro tube lightbox thinking it would produce perfect blue prints...
… boy was I wrong.

No where near enough power

BJ68 said:
For cyanotype workshops (with children) I use a UV cluster made of 5 Osram Ultra-Vitalux lamps
https://www.osram.com/pia/ecat/ULTRA-VITALUX-Ultraviolet lamps-Specialty lamps/com/en/GPS01_1028569/PP_EUROPE_Europe_eCat/ZMP_60829/
which are installed at a "Lochblech" (perforated metal plate) with porcelain E27 lamp holders.

Exposure times are 5 min (safe side) or less and it seems that the UV makes no sunburn at the skin, because a few kids and I (as the first one) made a print of our hand as test.

Two disadvantages:

a) The lamps have to be always on, even it the device is not used...
b) It consumes 1.5 kWh for every hour.

Plus the floor is heated to about 30°C if the device is installed about 60 cm above the ground.

Bj68

Metal Halide lamps for printing

lucille

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