Sessional_Paper_1949 — Page 46

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Examination of this consignment, therefore, should yield valuable informa- tion as to the 144 drums in the Wing On godown. We are thus enabled, as it were, to examine the material as it was before the fire. This examination will be two-fold, concerning itself, firstly, with the general properties of this washed film; and, secondly, with its stability, or, conversely, its liability to self-ignition.

(i) General properties.

The film is packed in the form of tight rolls of varying sizes, but normally 8-12" in diameter. These are placed as tightly as possible, in layers within the drum until the whole is full. Normally, a paper sack is first inserted into the drum, so that the film does not touch the metal. In 28 drums out of 30 examined, this sack was present, in two it was absent.

The nett weight of film per drum is about 500 lbs. The drums have a well-fitting lid which is not, however, airtight. Many of the drums bear a label from 20th Century Fox Film Corporation, consigning them to:

Messrs. Strong Cellulose Products Corporation,

OGDENSBURG, N.J., U.S.A.

The internal conditions of the drums is very variable; some are clean and bright, and others heavily rusted. This rusting can usually be traced to seepage of water through the lids at their junction with the drum bodies.

In one drum, pieces of unwashed film were found underneath the paper bag, together with a "Fox film" label. It may reasonably be conjectured that waste film is shipped by 20th Century Fox to the Ogdensburg firm in these drums; it is washed at the latter factory, and then re-packed in the same drums.

The film itself is rather variable in appearance. The greater number of the rolls are yellowed and have coalesced into firm blocks; the film can, however, easily be unwound. Some of the film is grayish in colour; the rolls of this film tend to be looser and less coalesced. In the drums where the film was in contact with rusty iron, the former is much stained and discoloured.

Within the rolls of film are a number of "Splices", or joins made with film cement. These are of two kinds. The first type is small and neat, and is the normal repair made to films broken during projection. The other type of splice is large and rough, and was in some cases supplemented by the use of metal staples. This type of splice was perhaps made in the film-washing plant to obtain continuous lengths of film to go through the machine.

The film was on the whole clear, but contained many smears, spots and black patches, which were found to consist of traces of the emulsion not removed in the washing process.

(ii) Stability and liability to self-ignition.

Having established the variability in condition of this film, it was felt that it should be sampled as extensively as possible, and stability tests performed thereon. Accordingly, Insp. Shaw and I visited Macao, to which place the film had been moved in the meantime, and opened 30 out of the 80 drums, extracting samples of all types of material found.

These were then tested in the laboratory for their stability; that is to say, for their resistance to the decomposition and self-ignition reaction already referred to. As has already been indicated above, the factors producing self-ignition are rather subtle and imperfectly understood; but the best generally practicable test consists in heating the material at 160° Centigrade. Under these conditions, a good and stable celluloid should survive at least one hour without decomposition or "puffing"-the latter word indicating the sudden vaporization of the material, accompanied by flaming, to which we have already referred.