Repairing a cement splice
The first step in re-cementing splices that have broken apart is to gently scrape away the dried cement. To accurately realign the two sections of film it might be possible to use a commercial splicer, depending on the degree of shrinkage. If the shrinkage is too great then a splice can be made entirely by hand using the following method.
- Clean up the broken sections of film by gently scraping away any dried cement with a scalpel. Take care not to scrape too deeply as this will weaken the film base. If the base is scraped too far the splice will not form a good loop and will will be unstable during transport. It will also tear more easily.
- Tape one section of the film by its edges to the workbench, carefully align the second section using a straight edge as a guide and another piece of film to ensure the perforation pitch is correct, Fig 11.1 ii.
- When the film is correctly positioned tape one edge down so that the film can be lifted, Fig 11.1 iii.
- Lift the free edge of the film and apply the cement from the centre out along the splice edge, Fig 11.1 iv. Don’t apply to much as the cement may bleed out of the repair and mark the surrounding film leaving a blemish. Press down gently for a few moments. Repeat on the other side, again making sure no cement spills from the repair area.
A small piece of folded paper that goes under the fixed section of film and over the other section of film will absorb any excess cement and prevent finger marks on the film.
Sometimes if the splice has been poorly made originally, or poorly repaired at some stage, the base will be very thin caused by too much scraping. A cement splice would require the loss of a frame as there may be too little film left to effectively splice too. To prevent the loss of a frame splicing tape can be used, however tape does raise a few concerns on the preservation of the film.
- Tape splicers are designed for release prints and have long pitch and cutting teeth that match the KS perforation shape. If the film is at all shrunken then this is an unsuitable technique as the cutters will cut away sections of the film around the perforations making the film less stable during machine transport.
- Not all tapes are suitable for use with photographic materials, any tape used must be tested for compatability with a Photographic Activity Test (PAT).
- Over time, even with tapes that have passed the PAT, the adhesive may spread or 'creep’. This can cause the film to attract dust or stick together. In either case the adhesive residue will need to cleaned off
To tape by hand carefully align each section of film (as in the previous technique) and apply tape to the base only. Trim the excess away using a metal straight edge and sharp scalpel. Cut the tape away from the perforations using a pointed scalpel blade.
Alternatively, a butt splice can be made. Clean up the broken edges of the film, align the two parts, emulsion down, so that the pitch of the perforations match. Tape the films down with a small section of masking tape so that the tape does not cover the splice area. From a piece of scrap film cut a small section to be used for reinforcing shaped as in Fig 11.2.
Scrape all the emulsion off the reinforcing section and align it across the splice. If you wish you can tape one edge of the section to hold it steady while you apply the cement. Working from the centre of the repair piece out, apply the film cement. Do not used to much cement otherwise the splice will be weaker. Hold the repair piece in place for a few seconds. Then working from the centre again, cement the other side.
When removing emulsion to make any repair it is important to make sure that all the emulsion is removed from the area where you wish to apply film cement. If you don’t then the splice will not be strong and will probably break when the film is used.
It is also important not to scrape to much away. If too much film base is scraped away, then the chances are that the cement will cause the repair to buckle.
Finally you could remove one or two of the frames and make a new splice. This may not be desirable for a number of reasons. If frames are removed then any sound components, such as sound negatives, will fall out of sync. Again if there is a sound component on the film then sound will be lost from the scene twenty frames ahead.
If you decide that the only successful way of repairing the film is to make a new splice then the following technique will allow a hand built splice that maintains the shrinkage.
- Trim the film as shown in Fig 11.4 i and ii. Scrape all the emulsion away from the frameline on the film with the edge flaps. Lightly scrape the base side, this is just to ensure that the cement has some 'fresh’ base to bond to.
- Use the perforations to align the film sections, Fig 11.4 iii, emulsion down. It may be helpful to tape one of the pieces of film down. Apply film cement along the scraped section and press the films together. The perforations that were used to guide the position of the films ensures that the exact shrinkage of the film has been matched during the repair.
Sometimes splices will be found that have buckled with age. These were probably due to a poor attempt at repair at some stage in the film’s life. These splices will cause the image to jump during transport and so should be repaired. With care it is possible to pull an old splice apart. The trick lies in deciding which option to use for the repair.