Film-Tech Forum ARCHIVE: Intermissions, planning and longevity of carbons

This is topic Intermissions, planning and longevity of carbons in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Robert Harris (Member # 1712) on 08-11-2003, 08:43 PM:

I was about to post to HTF in a thread regarding intermissions and thier necessity.

I'm certain that someone (or several) here can tell me how long the average carbon lasts for arc projection, ie., how often do the rods needs to be replaced?

RAH

Posted by Gordon McLeod (Member # 33) on 08-11-2003, 09:16 PM:

It is very dependent on the lamp type carbon trim and current
A superex trim say 7mm neg and 8mm postive will burn 40 min at 65amps before the but needs to be moved forward in say a magnarc to get one more reel but at 60 amps it will do 1hour
A futura with joinable carbons acan typically do 61-65min on a trim at 135amps

Posted by Steve Kraus (Member # 476) on 08-11-2003, 09:36 PM:

I remember running hour reels on Futuras with no problem. In fact IIRC the positives (uncoated, rotated and moved forward by knurled rollers, current entering the rod close to the business end via water cooled silver contacts) could probably have gone 2 hrs. The negative (copper coated) was long enough as well but the negative mechanism which was a screw feed only had a bit over an hour of travel at whatever current we were running at. You clamped a new negative near the middle and after an hour reel cranked the mechanism back down and clamped it at the end for another one hour run. An adventurous machinist could have created modified components for a 2 hour Futura.

Posted by John Pytlak (Member # 331) on 08-11-2003, 10:50 PM:

The National Carbon Bulletins (December 1957, Issue 3) published burn rates for various trims:

http://www.film-tech.com/manuals/CARBONBULLETINS.pdf

Posted by William Hooper (Member # 71) on 08-12-2003, 12:40 AM:

About two reels is a very gross, general, sight unseen mental measure.

Posted by Tim Reed (Member # 137) on 08-12-2003, 07:26 AM:

Joinable carbons are no longer available.

Posted by Scott Norwood (Member # 30) on 08-12-2003, 07:44 AM:

I'm pretty sure that we could do 60 minutes with Enarc lamps and 7mm x 9" and 8mm x 14" carbons. For a full 20-minute reel, we burn about 4 1/2" of positive and 1 1/2" of negative, so the carbons are long enough. I don't remember offhand how long the "carriage" (or whatever the proper term is) is for the positive, though, so it might not be possible without stopping and re-setting the positive carbon. I haven't run Peerless lamps lately, but I think that the situation is pretty much the same.

On the other hand, I've seen some Ashcraft lamps which won't burn more than about 30 minutes per trim.

I guess that the answer, then, is "it depends."

Posted by Mitchell Dvoskin (Member # 751) on 08-12-2003, 08:08 AM:

My experience has been 40 minutes in most theatres I worked in that ran carbons back in the 1970's. You could get another 20 minutes out of a set of carbons, but you needed to stop and re-seat them in the jaws after 2 reels. There were some theatres that were exceptions to this, but in general, 2 reels uninterupted was maximum.

Before my time, but it is my understanding that when 3D was introduced (Polarized duel projector), the power to the lamphouse was reduced to allow for the 60 minute burn time. The lower light output was compensated for by the fact that you had 2 projectors (and 2 lamp houses) lighting the screen.

Other than 3D where both projectors were being used at the same time, I do not believe carbon burn time had anything to do with intermissions. Theatres projected directly from of 20 minute reels, switching between the 2 projectors. In non 3D films, the only reason there would be an intermission was so that people could go to the bathroom and buy more popcorn. There was no technological reason for it.

/Mitchell

Posted by Gordon McLeod (Member # 33) on 08-12-2003, 11:31 AM:

Morganite used to make 16 inch versions of the superex carbons and their lamphouse the autoarc would run 69min on a full trim at max amperage with the longer carbons
Also some of the Kalee lamphouses allowed the full 14" stick to burn in one pass

Posted by John Spooner (Member # 1565) on 08-12-2003, 11:44 AM:

With this fellow here, we get 65 mins maximum from a full trim of 7x9 negative and 8x14 positive carbons.
Currently using the Indian Schutz carbons.

Posted by Stephen Furley (Member # 1277) on 08-12-2003, 03:00 PM:

President arc, mech looks like a 20 or 21. Nice condition, but it looks a bit odd without the spoolboxes. It looks like new, and it must be at least forty five years old now. I take it those are 6000 foot spools you are running there. Kalee did make 6000 foot spool boxes, they weren't common, but a pair of machines installed in the National Film Theatre at one time had them, for running two strip 3-D, as did the Kalee Vistavision projectors, of which I believe four were built.

Do you only have one machine? There obviously isn't one behind the port in the foreground, is there another one behind the camera?

If you only have one, how are you managing with a 65 minute run time? Is it an application where you only need to run shorts?

What do think of the Schutz carbons? I've heard varying reports of them.

Posted by Leo Enticknap (Member # 534) on 08-12-2003, 03:25 PM:

Those spools look like the Cinemeccanica plastic ones. They'll hold 75 minutes of polyester easily.

Posted by Scott Norwood (Member # 30) on 08-14-2003, 07:44 AM:

I took a closer look at the Enarcs last night; it looks like the positive feed mechanism can only feed about 10" without stopping and re-setting the carbons, so for us that would be about 45 minutes' worth of continuous running time.

Posted by Robert Harris (Member # 1712) on 08-14-2003, 09:13 AM:

How did I know that this group would have the answsers?

Thank you to all.

RAH

Posted by Frank Aston (Member # 478) on 08-14-2003, 05:00 PM:

Hi Robert,

Given the fantastic resoration work with which you've been involved, can I ask what precipitated the question?

Kind regards,

Frank.

Posted by John Spooner (Member # 1565) on 08-15-2003, 02:19 PM:

Dear Stephen and Leo.
The projector is a 21,runs very well. The other projector is not in the picture, this one is our left hand side projector, the other one being identical. They are installed in one of our theatres where we retained carbon arcs.
The Schutz carbons while certainly nowhere the quality or consistency of Double Eagle are nevertheless quite adequate for the job. They have a slightly lower colour temperature, burn well and are cheap. Every now and then we encounter a negative with a faulty core causing the flame to rise up and the light drops, by keeping the gap small when this occurs the flame descends back to its proper position.
The spools are Cinemacannica as Leo observed, we often put 75 -80 mins of film onto them in the xenon theatres, at this theatre we can only get 65 mins max onto a spool as a full trim will run no more than this time.
Apart from the spool arms they are as original except the round motor switch has been replaced with a toggle switch and a timer circuit replaces the original start/run resistance which gives a controlled start for the large spools.
John Spooner.

Posted by Robert Harris (Member # 1712) on 08-15-2003, 09:41 PM:

The question was precipitated by a discussion on HTF re: intermissions as a part of roadshow performances and the concept by some that they were not designed in as part of the script, but rather, a bladder break.

I was wondering if their might have been some additional technical rationale, ie, possibly allowing a lampt o cool (in olden days) to allow the replacement of carbons.

Historically, I've noted that there have been more (additional) intermission breaks or "intervals" in the UK in titles like Navarone, then we have here in the Colonies.

RAH

Posted by Steve Kraus (Member # 476) on 08-16-2003, 01:30 AM:

Nowadays in the single projector era many longer films are shown overseas with an intermission though they had none in their domestic USA release because while here the platter is pretty much universal when it comes to single strand film handling in other countries the giant reel film transport is common and many of these are of limited capacity. These intermissions are sanctioned by the distributor who direct where they go and generally will supply an apppropriate film strip.

Posted by Warren Smyth (Member # 1838) on 08-18-2003, 04:14 AM:

Many thanks to Robert who has raised a subject that takes me back at least a year or two. In my part of the world we always had intermissions. The first half would include a news reel or two, a short and maybe a cartoon. The first half would start with the queen trailer and finish with a trailer for the next attraction. With the roadshows which became common in the sixties, the intermission was often printed in, examples being My Fair Lady and Chitty Chitty Bang Bang which had a repeat of the action at the start of the second half. In these instances, the intermission breaks were definitely planned. Several films had overtures and entr'ctes at the start of the second halfs. There were however, some, such as West Side Story where we had to force the break. In those instances, we would search through for a fade out or scene change when we made up the print. Alternatively, the film distributor or previous projectionist sometimes suggested a suitable place. The distributor sometimes would splice in an intermission title which contained a friendly request to patrons that they be seated promptly for the start of the second half. The second half would be preceeded by a title which said "Part Two Begins".

Carbon consumption and heat from arcs were not factors in the determination of the intermission. In those days, there were no platters and large reels. Reels were run separately on two projectors. In New Zealand in fact it used to be illegal to have more than 2,000 feet of film on a reel because of the fire hazard of nitrate. Special dispensation, was made for wide screen systems such as three strip Cinerama.

It wasn't untill the seventies that I started using 6,000 ft reels. I was able to get one hour and eight minutes out of one trim. This was possible using 9mm and 10mm carbons, the latter being 18inches long. The longer model of the Cinemeccanica lamphouse provided full travel for the 18inch rod. We burnt at about 110 amps. One had to keep an eye on the meter though, with a full reel, as a slight increase in line voltage which tended to happen when the shops closed at night, could leave you running out of carbon.

By the way, just as an increase in current can shove up the burning rate so the opposte is true. I have basicly the same plant as John shows in his photo, Kalee with President arcs. On a tower with 10,000 foot reels I can get 2 hours without a break. How? by under running the carbons. I use 6mm and 7mm positives and burn about 40 amps. Less than that, and the arc becomes unstable. I do however have to "Slip" the negative. This is the practice of loosening the crutch while the arc is running and slipping it back while holding the carbon stationary with insulated pliers. This gives a few more inches of travel. The secret is to loosen by just the right amount so as to maintain electrical contact and avoid arcing between the crutch and carbon. This is not recommended unless you know what you are doing. "But what a terrible light!" you may say. Well I don't need much. The screen is only 11 feet wide on scope in my basement theatrette.

Well that's about enough for a first attempt. Thanks Robert, for the memory of intermissions, overtures, entr'actes curtains, presentation and 70mm.

Posted by William H. Ward (Member # 1797) on 08-20-2003, 10:45 AM:

In the golden years of carbon-arcs, most Suprex lamps I've worked with using 20min reels, was the 7 and 8mm trim at 65/70 amps. We then installed BIG reels (old 3d 5000 footers) and began burning 8 and 9mm trim at 60/65 amps. Got the full reel and some to spare. Arc was stable from a generator and light was decent on the screen.

Posted by Frank Aston (Member # 478) on 08-22-2003, 05:17 PM:

Sorry to harp back to this topic but I find the whole subject of PROPER intermissions fascinating. Not the ones inserted willy-nilly by greedy cinema operators merely to sell more popcorn but a natural break in the proceedings, usually at a suitably dramatic moment planned by the film-makers.

The effect was often thrilling. It enabled the audience to take stock of events so far, look forward to the continuation of the story and, or course, get a drink or let one out!

Two of my favorites were BEN-HUR which comes 135 minutes in and finds Judah Ben Hur striding off through a swirling night wind and blowing leaves, with a grim resolve to gain revenge on those who seemingly have been responsible for the death of his mother and sister. (Actually, they're in a leper colony). Miklos Rozsa's music swells and a glorious INTERMISSION title appears in gold.

Coincidentally, the other movie features Charlton Heston and music by Rozsa.

This one is EL CID when the exiled Rodrigo has been reunited with his beloved wife and resolved to settle down to a quiet life together. Unfortunately hundreds of followers have different ideas. They beg him to lead an army against the Moors and, leaving Sophia Loren in a convent, he marches out at its head. Cue wonderful slow fade and INTERMISSION.

LAWRENCE OF ARABIA, SPARTACUS and MY FAIR LADY all majestically restored by Robert Harris and his associates had equally thrilling and appropiate intervals and I would be intrigued to know if these presented any particular challenges, either visually or audibly, to the recreation of the origional experience.

Kind regards,

Frank.

Posted by Robert Harris (Member # 1712) on 08-22-2003, 07:50 PM:

Frank Ashton wrote:

"LAWRENCE OF ARABIA, SPARTACUS and MY FAIR LADY all majestically restored by Robert Harris and his associates had equally thrilling and appropiate intervals and I would be intrigued to know if these presented any particular challenges, either visually or audibly, to the recreation of the origional experience."

Frank,

I'm not certain precisely what you're asking... ie, a general query re: restoration or Intermission titles and tracks in general. If you'd care to be a bit more explicit, I'd be happy to offer what I can.

RAH

Posted by Paul Cassidy (Member # 951) on 08-23-2003, 12:07 PM:

As I remember when a young fellow ,we always had the News Reels and then the Cartoons ,Serials then Intermission , Feature starting after that , the exception being the movies advertised with "Feature Occupies Entire Program" the Inermission being close to the middle of the film , the public in the end got tired of the lengthy programs and began to come only for the start of the movie proper ,always enquiring when buying tickets what the start time would be , then going off for a bite or drink and returning for the start of the feature , Kerridge Odeon dropped the Intermission all together but their opposition Almagmated Cinemas stuck with them for awhile ,until the value of more sessions per day swayed them , until then there were normally only 4 sessions per day 11am ,2pm ,5pm and 8pm .

Posted by Martin Brooks (Member # 1269) on 08-23-2003, 06:05 PM:

quote:
There were however, some, such as West Side Story where we had to force the break. In those instances, we would search through for a fade out or scene change when we made up the print.

I'm surprised because "West Side Story" definitely had a planned intermission in its original roadshow release in the States. I remember seeing the film at the Rivoli in New York and the intermission came after the Quintet and before the Rumble. I don't remember if there was entrance music before the second half as there was at the beginning. I haven't seen the newly remastered DVD so I don't know if they included an intermission on there.

Posted by Warren Smyth (Member # 1838) on 08-24-2003, 06:00 PM:

quote:
West Side Story definitely had a planned intermission in it's original Road Show release in the states.

The 35mm prints which came down here certainly had no provision for intermission. The break mentioned, would have come quite late into the film which would have made a long first half. This may have been deemed too late and the decision taken to close up the break at this point for foreign release. The transition before the rumble was seamless in our prints so there may have been two versions.

United Artists sometimes spliced in a standard intermission title so this could have been inserted at a latter point. I know that I broke it after the 'Tonight' duet and Tony walks down the street into the distance. Part two then opens with Marie in the dress shop and sings 'I feel pretty'.

West Side Story had no entr'act in our prints but had the overture with a graphic design which changed colour and brilliantly disolved into the first shot, an aerial of New York.

It had no playout but a long end credit sequence, again brilliantly done. I haven't bought the dvd set yet so it will be interesting to see if we missed out on any components. West Side Story is still one of my favourites and remains timeless.