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Topic: Dangers of Thorium in Carbon Arc gear?

Henry Titchen
Film Handler

Posts: 31
From: Singleton, NSW, Australia
Registered: May 2005

posted 05-04-2005 03:25 AM

Has anyone any knowledge on the dangers of Thorium in carbon arc rods? Is it possible to buy arc rods free of Thorium?

Thanks From,
Henry.

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John Pytlak
Film God

Posts: 9987
From: Rochester, NY 14650-1922
Registered: Jan 2000

posted 05-04-2005 08:04 AM

The National Projector Carbon Bulletins called them "rare-earth compounds that provide the special qualities of the light". Do you know for certain they included thorium salts? [uhoh]

I certainly would wear protective gear when cleaning the ash, to avoid ingesting or breathing in any particulates. Treat it the same as you would asbestos particles. And don't heat open containers of food in the lamphouse. [Eek!]

Thorium salts:

http://physchem.ox.ac.uk/MSDS/TH/thorium_nitrate.html

quote:
Toxic in contact with skin and if swallowed or inhaled as dust. This material should be treated as a potential mutagen and carcinogen....Safety glasses, protective gloves and good ventilation. In the U.K. users must give at least 28 days notice to the Health and Safety Executive before working for the first time with more than 0.6g.

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Frank Angel
Film God

Posts: 5305
From: Brooklyn NY USA
Registered: Dec 1999

posted 05-04-2005 08:30 AM

Does this thorium decompose in the arc plazma? You would think anything subjected to that kind of heat would be turned into a lump of inert stuff. Geez, and to think I used to heat my food all the time....and light my ciggies on the rods just after I extinguished the arc (wisely I stopped smoking when I was still in my 20s). But I never took any particular precautions when vacuuming the stack or the lamphouse itself of soot/ash. I guess I should consider myself lucky.

Mutagen, huh?! Hmmmm, maybe that is what's cause that third eye to grow in the middle of my forehead. [Eek!]

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John Pytlak
Film God

Posts: 9987
From: Rochester, NY 14650-1922
Registered: Jan 2000

posted 05-04-2005 08:40 AM

quote: Frank Angel
Does this thorium decompose in the arc plazma?

If elemental Thorium is the issue, it would remain in the ash.

It's been over 35 years since I regularly (mis)handled carbon ash, and still no adverse health effects. I also (mis)handled asbestos furnace cement and "Transite", heated molten lead to make fishing sinkers, used carbon tetrachloride to clean bicycle parts, and played with mercury in those environmentally unenlightened days. [Eek!]

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Martin Brooks
Jedi Master Film Handler

Posts: 900
From: Forest Hills, NY, USA
Registered: May 2002

posted 05-04-2005 12:47 PM

quote: Frank Angel
Mutagen, huh?! Hmmmm, maybe that is what's cause that third eye to grow in the middle of my forehead.

Yeah, Frank....you really ought to do something about that eye. How do you watch 3D with that thing?

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Stephen Furley
Film God

Posts: 3059
From: Coulsdon, Croydon, England
Registered: May 2002

posted 05-04-2005 01:20 PM

Morgan used to make carbons for various purposes, and there were several different core types, giving different spectral properties. Low intensity, uncoated types, used in things like sun lamps and printing down frames used to have coloured paint on the end of them to identify the core type, but I've not seen this on projector carbons. I've certainly seen ones which used cerium salts in the core, but I can't remember whether they were projection ones, or for some other purpose.

I've got a box of strange carbons somewhere; they're Morgan LCT (Low Colour Temperature?) They give a light which seems to be somewhere between a tungsten lamp, and a SON (high pressure sudium). They're difficult to strike, difficult to keep the arc stable, and produce much worse fumes than the normal ones.

I saw 'The Great Dictator' at the Loew's Jersey on Sunday afternoon; I wonder if this will be the last film that I'll ever see, at a public cinema, projected by carbon arc. I think it's quite likely.

How many people here are still burning carbons, and do you have plans to convert?

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Monte L Fullmer
Film God

Posts: 8367
From: Nampa, Idaho, USA
Registered: Nov 2004

posted 05-04-2005 01:52 PM

Brother! .. and how many times that I've swept out many-a-lamphouses of carbon ash, got on my hands, whiffed the dust, and cleaning out exhaust housings loaded with that stuff..

..and degreased many-a-items with Carbon Tet...

Now, I'm glad I started to play with xenon bulbs over 20 yrs ago..

-Monte

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William Hooper
Phenomenal Film Handler

Posts: 1879
From: Mobile, AL USA
Registered: Jun 99

posted 05-05-2005 12:21 AM

quote: Stephen Furley
How many people here are still burning carbons

I think Scott Norwood does someplace, & I do occasionallly.
The last one was a couple of months ago, when I ran a movie for Elvis.

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Scott Norwood
Film God

Posts: 8146
From: Boston, MA. USA (1774.21 miles northeast of Dallas)
Registered: Jun 99

posted 05-05-2005 07:33 AM

I can think of a few places that still run carbon. I have been known to work at the Avon Cinema in Providence, RI from time to time. They are still running 8mm and 7mm carbons in Enarc lamphouses on a daily basis.

In the past, I have worked at the Cape Cinema (Dennis, MA.), which is open seasonally. I am told that they still run carbon (6mm and 7mm in Peerless lamps).

Other carbon houses that I can think of offhand: IOKA (Portsmouth, NH), Cinestudio (Hartford, CT.), Wellfleet DI (Wellfleet, MA.), and maybe a few others.

There are other uses for carbon arc lighting besides film projection, too. I recently had an interesting conversation with someone who was operating a WWII-vintage searchlight, which burned very thick carbons (non copper-coated) and is one of the brightest man-made light sources available. They were originally built for detecting enemy aircraft (in the pre-RADAR days), and are now used for advertising car dealerships and movie premieres. Carbons are also used in older followspots and I believe that they also have some application in offset printing (exposing plates, I think). Arc lamps (Mole Brute Arcs) are sometimes used in film prodution as well.

Possible health risks aside, I love the look of carbon arc light and I think that there is something worthwhile about keeping alive the earliest practical form of electric illumination.

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Stephen Furley
Film God

Posts: 3059
From: Coulsdon, Croydon, England
Registered: May 2002

posted 05-05-2005 08:36 AM

quote: Scott Norwood
I can think of a few places that still run carbon. I have been known to work at the Avon Cinema in Providence, RI from time to time. They are still running 8mm and 7mm carbons in Enarc lamphouses on a daily basis.

In the past, I have worked at the Cape Cinema (Dennis, MA.), which is open seasonally. I am told that they still run carbon (6mm and 7mm in Peerless lamps).

Other carbon houses that I can think of offhand: IOKA (Portsmouth, NH), Cinestudio (Hartford, CT.), Wellfleet DI (Wellfleet, MA.), and maybe a few others.

I think there's only one left in Britain now, and I've never been there; it's the other end of the Country. The last I heard, The Dome, Worthing, still had one of their old projectors, and could still runn the odd reel on it.

quote: Scott Norwood
There are other uses for carbon arc lighting besides film projection, too. I recently had an interesting conversation with someone who was operating a WWII-vintage searchlight, which burned very thick carbons (non copper-coated) and is one of the brightest man-made light sources available. They were originally built for detecting enemy aircraft (in the pre-RADAR days), and are now used for advertising car dealerships and movie premieres.

You should see the price of those carbons now!

quote: Scott Norwood
Carbons are also used in older followspots and I believe that they also have some application in offset printing (exposing plates, I think). Arc lamps (Mole Brute Arcs) are sometimes used in film prodution as well.

The last place I saw running carbon spots here was about six or seven years ago. The London Palladium still had them not so very long ago, but I suspect that they've gone now. Very few, if any platemakers are still using them now, though it's not that many years ago that they were still quite common.

The last brutes I saw being used on location were at London's St. Pancras Station, quite a few years ago now; I don't know what the production was. Everything seems to be HMIs now.

They were also used in sun (health)lamps, and 'fadeometers', and an arc struck between a carbon electrode and the specemin was used in spectrometers.

Also used in the lab for producing BuckminsterFullerine (C60).

I'll be sad to see the last one go, but I don't think it can be long now. I would guess maybe 2-5 years until the last cinema converts, or closes.

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Leo Enticknap
Film God

Posts: 7474
From: Loma Linda, CA
Registered: Jul 2000

posted 05-05-2005 08:48 AM

quote: Stephen Furley
I think there's only one left in Britain now, and I've never been there; it's the other end of the Country.

If you mean the Tyneside Cinema in Newcastle, then they still burn carbons. Or at least they did in screen 2 when I last saw a film there, just over a month ago.

The Tyneside might be at the other end of the country, but at least it's on this side of the Atlantic! That having been said, it's certainly less stressful getting from here to the USA than it usaually is trying to get from York to London.

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Robert Throop
Master Film Handler

Posts: 412
From: Vernon, NY USA
Registered: Jun 99

posted 05-05-2005 08:58 AM

The Capitol in Rome, NY still runs 11mm carbons in Core Lites pretty regularly as does the Stanley in Utica and the Landmark in Syracuse.
Bob

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Tim Reed
Better Projection Pays

Posts: 5246
From: Northampton, PA
Registered: Sep 1999

posted 05-05-2005 11:09 AM

SSSSSNIIIFFF!! Aaaahh! I love the smell of carbon ash in the morning!

Pretty good on sandwiches, too! [Razz]

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Kenneth Wuepper
Phenomenal Film Handler

Posts: 1026
From: Saginaw, MI, USA
Registered: Feb 2002

posted 05-05-2005 12:45 PM

The Temple Theatre here in Saginaw Michigan still runs 35/70 with Ashcraft lamps and 13.6mm Positives and 7/16in. Negatives at 160 Amperes. We will continue to use Carbon as long as the rods remain available and with any quality. Our last batch of Nationals came from a closed Cinerama Theatre.

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Henry Titchen
Film Handler

Posts: 31
From: Singleton, NSW, Australia
Registered: May 2005

posted 05-05-2005 04:12 PM

I have carried out some more "Google" research into potential carbon arc issues. I have absolutely NO medical background.

This web page details some interesting information on "potential" issues with rare earths...news to me!

Effects on projectionists using carbon arcs

The following web page has a very interesting report as well. To quote "a relation between the observed interstitial lung fibrosis and occupational exposure to RE is highly probable."
RE means "Rare Earths"

Further study analysing projectionists lungs

Henry

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