PSLC - The Macroplex Cinema

Polymers in Film Production
Director: That's a wrap!
So now that we're done shooting we have to edit all this. It might seem simpler than it is though. Editing is a long process and there are an awful lot of polymers involved. One of the first things that needs to be done is printing the film and the sound transfer. The negative that we ran through the camera is processed and then printed. rolls of workprint This "work print" is printed sort of the way photographs are printed from negative onto paper. Instead, these thousands of frames are printed into a new piece of film as positive images. These films are all - of course - cellulose acetate.

The sound is tranferred from the quarter inch audio tape into MAG STOCK. It is polyester film stock that instead of picture emullsion is coated with metal oxides just like tape. The reason we put sound on mag stock is so that we can use the perforations - which are just like those on film, to synchronize the sound and picture exactly in the editing stage. The sound runs at exactly twenty-four frames per second like the film. And like the film mag stock is pretty sturdy, due to the fact that it must be run through the editing machine over and over.

Steenbeck flarbed editor When everything is printed and transferred and back from the lab, then we have to synchonize it all. The best way is to look at the film and mark each frame where the slate claps, and then mark the sound track at the exact point where the clapboard hits. This is easily done on a flatbed editor like this Steenbeck machine, which itself has a few polymer features, like all the polyethylene spindles and those little nylon rollers and the diffuse Plexiglass screens where the images are projected through a prism and a mirror.

Then we go to the sync block and use Mylar leader, which is made of a polyester film, to add to the picture reel to make it match up with the sound (The sound track is always longer becasue we start running tape first on the set). This Mylar leader is crosslinked to make it extra strong and resistant to heat and cold, and leader comes in a variety of pretty colors as well as single and double perforated. Despite its beauty, leader is also very functional. We can put it in place of damaged frames of the work print... It happens... those machines get hungry sometimes. plastic leader We can also put it in place of shots that need to be redone or have't been shot yet, just to get the timing ot a scene right. We also use it to fill the gaps in the multiple soundtracks that we will be using. And you just thought this leader stuff went at the beginning of all those cheesy old films that you watched in elementary school... Wait, you may not be that old, but some of us remember it.

a splicer and both types of tape So how do we get it all to stick together? Well, at this point nothing is permanent. All editing decisions can be changed, so we use a lot of SPLICING TAPE. We use clear for picture, and the thicker white for sound. Fortunately both types of "film" can be cut and spliced with the same splicer, but constantly switching out the tape can make life rough for the editor.

And now something you might have noticed everywhere - these little yellow cores. They are also made of hard polystyrene, and they are very important in the editing process. The further we get into the edit, plastic cores for 16 and 35 mm film the more of these things we need as we break down scenes and separate different soundtracks, like the dialogue track and the sound effects and the music. Each reel needs its own core. It is not unusual to use 50 to 100 cores when editing a short film. It may seem a precarious way to store film, and it is. Bigger reels must be handled with care so that the core doesn't slip out of the center, but cores make the film easier to load onto different types of editing machines and projectors. There are special "split reels" with removable flanges that can be put onto a projector or a bench editor and then removed from the core when the work is done.
Once the work print and all the soundtracks (There can be as many as twelve or twenty-four - or more - on major motion pictures) are the way we want them, we LOCK the tracks, which is a filmy way of saying we declare the thing finished. hot splicer and cement This is important because once we mix the soundtracks there's no going back. So while the soundtracks are at the sound engineer being mixed onto a single track of mag stock, some very precise person has to match the camera negative to the work print. It takes a long time to go back through all the original rolls of film and find just the little pieces that you used in the final edit, but it can be done with a system of edge numbers which are the same on workprint and negative.

Then the negative is carefully spliced together in a VERY CLEAN ROOM. You can't get any dust or junk on it at all. You also can't use tape to put it together, so splcing cement and a heat splicer are used. The cement is essnetially made of the solvent acetone, which partially dissolves the
acetate base material of the film. Cross section of a negative splice The edges of the film are brushed with cement and then set in perfect alignment in the heat splicer. The low heat on the splicing block mainly speeds up the drying process which fuses the film together once the solvent has all evaporated. So a good film splice should act as if it is a single unbroken piece of film.

And this is probably more than you wanted to know, but the ends of the shots cannot be spliced together on the negative becasue cement splices must always be base to base. If we spliced negative base to base, every other shot would have to be backwards. There also must be time for the printing machine at the lab to adjust itself to the proper color settings for the next shot in the sequence.
An A/B roll pattern used in splicing together film negative
So we make two reels and alternate the shots with acetate leader coated with black emulsion. The acetate base of the leader will - of course - splice to the negative. On the "A" roll are odd numbered shots, and on the "B" roll are even numbered shots in a sort of chekerboard pattern. This way of splicing keeps all the shots facing the right direction and also allows for seamless printing of one shot after another on the release print.

These days new digital media has caused a lot of changes in the film production process. Amateur filmmakers are turning to digital video, mostly for the sake of convenience and availability of consumer level computer based editing. However, after dubbing and editing suite time are figured in, broadcast qulaity professional video comes out costing almost as much as film. Digital editing of film has taken some of the steps out of the process, including workprint, mag sound track and actual cutting of the film. But nothing invented to date has been able to match the light sensitivity and resolution of film, so the negative, the release print, and good old-fashioned film shoots are bound to be around for a good long time. In fact some editors still prefer to work all the old fashioned way. There is something in the time it allows one to think about what one is doing, as well as the feel of actually working with the film itself, that makes the editing process valuable.


Polymer Science Learning Center
Special thanks to the University of Southern Mississippi Department of Radio, Television, and Film for the opportunity to get all the pictures on these pages and to Gregory Brust for aiding in the idetification of all these polymers.