Prints were often waxed to smooth their transport in the projector and hopefully increase their useful life and the process may have started very early indeed. There are many recipes for waxes in early and later literature, generally consisting of a wax, often beeswax, or white candle wax [paraffin wax], dissolved in a solvent. Xylene was used as the solvent but this has largely been replaced by 1:1:1 Trichloroethane as being a lesser hazard. The film was waxed either overall by dipping through a wax solution or over a waxed cloth roller, or, more economically, by application to the edges of the film only while still in the whole roll. In both cases, the film was usually then buffed to polish the surfaces applied, and dry the wax.
A waxed print drives through a projector more quietly than an unwaxed print, especially on old worn projectors. Old waxed prints are often extremely dirty - the old wax seems to pick up dirt easily. Wax is easily cleaned off by any of the solvents used for film cleaning.
The Vaccuumate process was introduced by Restoration House Inc. of Canada some 30 or more years ago as an overall treatment for film to improve the film suppleness, its lubrication and to give some protection from fungi and algae. It has been used very extensively especially for cinema prints prior to being sent to the tropics. A secondary use has been to treat films from archives that have already been affected by fungi or bacteria in order to kill the existing organisms and prevent continuing damage.
The process has not been used as widely as it perhaps should have been, since, like Redimension, secrecy over the chemistry has prevented many archives from understanding, and therefore using, the process. Without a full explanation of the components, it is not surprising that archive technicians are not willing to risk their films. This attitude is changing as the laboratories using the process publish the formulations.
The major benefit of the process is that it can take place without unwinding the roll and without passing the film through any liquid. The film rolls are placed in a vacuum chamber and the pressure reduced by a pump to 30 mm Hg. The temperature is controlled to 25C.
In a sequence that takes about 21/2 hrs five separate chemical mixtures are released into the chamber - these vaporise and are taken up by the film emulsion and /or the film base. The following is the description of the purpose of each solution as given by the licenser. The components in brackets are supplied by Paul Read at SoHo Images.
Solution 1 Reduces the excess moisture from processing [the chemical is acetaldehyde].
Solution 2 Conditions the base and emulsion, providing protection
against drying and brittleness [the chemistry includes
turpentine, various natural oils, and Genklene]
Solution 3 Hardens and toughens the film's emulsion [Acetaldehyde, Isopropyl Alcohol, water and oils]
Solution 4 Provides a permanent lubrication, ensuring that the film remains supple throughout its life, during use and storage [Genklene, Paraffin Wax and oils]
Solution 5 Provides an additional external lubrication for release
prints to be projected [much the same as 4 plus a
mineral oil]
Vaccuumate definitely has benefits. It is easy and economical to carry out. The resulting lubrication is excellent, the film base is undoubtedly less stiff, and the fungi are killed [by the acetaldehyde]. However, the process is probably over elaborate and some components are probably unnecessary. There is a general move recently to direct the process to deal with specific problems of film with specific chemistry and, as with Redimension, to publish exactly what is used so that archive technicians can select what they need and feel confident they know the full details of the process.
Permanent coatings generally date from film made after 1975, and generally, no solvent will be effective. The best known is Photoguard from 3M which is a liquid polymer coating cross-linked by ultraviolet irradiation The coat is much tougher than any other lacquer and was used on release prints and sometimes for duplicate negatives to extend the printing life. Some can be removed by very specialised techniques operated by the manufacturer's franchise. If it is considered necessary to remove these coating the manufacturer or their local franchise has to be contacted but removal may not be possible and the coating must then be considered as a permanent feature of this film.