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1952 Theatre Catalog, 10th Edition, Page 303 (267)

1952 Theatre Catalog, 10th Edition
1952 Theatre Catalog
1952 Theatre Catalog, 10th Edition, Page 303
Page 303

1952 Theatre Catalog, 10th Edition, Page 303

time under equalized pressure. For safety film, about 10 to 15 seconds is recommended. At the end of the bonding time, the pressure may be released and the finished splice rubbed slightly with a cloth (across the film; never in a direction parallel to the length of the film) in order to help seal the cut ends.

A good splice is actually a weld, one section of the film being partly dissolved into the other. It should be emphasized that it is important to bring the tw0 surfaces under pressure as quickly as possible after application of the cement. It is unnecessary, however, to slam the pressure clamp into position since this results in splashing of the cement. If the left clamp of the benchtop splicer is raised slightly when the cement is applied, a cleaner back surface will be obtained, since the cement will be less apt to flow under the film. This will greatly reduce the possibility of distortion in the spliced area when the cement has dried.

Some exchanges use one type of cement for nitrate film and another type for safety film. This practice has proved troublesome on numerous occasions. Cements are now available which will splice both safety and nitrate films equally Well if instructions are followed. It is important to use fresh cement and under no condition should used cement in bench bottles be returned to the supply container at the end of the exchange workday. Bench bottles should be cleaned out regularly and filled with new cement.

In many instances poor splices are attributed to the particular brand of cement being used, or the characteristics of the film. In most cases the failures may be explained by lack of attention to details covered in the above paragraphs. Helpful hints on splicing are given in the condensed- chart shown in Figure

Film Deformation

Motion picture film is in many respects similar to other plastic materials in that it has certain physical limitations. Despite every care taken in manufacture to assure a uniform and high quality product, certain distortions can occur through improper storage, through faulty handling and under very severe projection conditions. The various types of distortion are commonly referred to by exchange inspectors and theatre projectionists alike simply as ftwarping" or fibucklingf In many cases, the exchange is at a loss to understand the problems encountered by the projectionist because the description of the condition of the film has been inadequate. Likewise, conditions correctly described would help the laboratory locate the source of the difficulty. Whether it concerns the manufacturer, laboratory, exchange, or projectionist it seems likely that a uniform terminology pertaining to different types 0f film deformation will be of great assistance in locating the causes of such deformation and in eliminating further trouble. Some of the most common forms of deformation are illustrated in the views in Figure 33.)

Buckle: This type of distortion may be either temporary or permanent. Tem< POrarry buckle results from loss of moisture from the edges of the film when


FIG. 34. Blistering of film caused by severe projection temperatures.

rolls are stored under dry air conditions. Pemmment buckle is caused by loss of solvent from the edges of the film when rolls are stored under moist air conditions.

Edgeane or flute: This type of deformation may also be either temporary or permanent. Temporary edgeu'rwe or flute may occur along both edges as a result of elongation of the edges relative to the center of the strip during early storage under moist conditions. Permanent edgewave or flute may occur along one edge if there is a very slight thickness differential across the width of the film and if the roll is wound under high tension.

Twist: This effect is produced in new prints by loose winding of the film emulsion side in, under dry air conditions. If the film is wound emulsion side out under the same conditions, the undulations do not alternate from one edge to the other as shown in Figure 33, but are directly opposite one another.

Curl: This type of deformation is caused by dimensional differences between the emulsion layer and the support. It results from changes in moisture content of the emulsion layer and support with variation in relative humidity of the atmosphere.

Spoking: This type of distortion is caused by loose winding of film which has a high degree of curl. Permanent spoking is seen as twist when the film is unwound. Temporary spoking disappears when the film is unwound.

Embossing: This is a type of deformation which often occurs when prints are projected with high intensity lamps. The excessive heat causes actual expansion of the picture area, and the frame stands out in relief. This distortion has no

FIG. 33. Mosf common types of film distortion. (AhBUCKLE: Edges are shorter than the confer section. (B) EDGEWAVE OR FLUTE: lust the opposno of buckle. the edges being longer than the center section. (C) TWIST: Actually an exaggerated odgowave condition in which the undulahons extend to the confer of the film and alternate from one edge to the other. (D) CURL: The physiv cal shape of the film whereby one surface is shorter than the other. (Positive) Emulsion side is concava. fhis being the shorter surface. (Negative) Support side is concave. this being the shorter surface. (E) SPOKING: A condition involving winding tension and excessive curl. (F) EMBOSSING: The result of excessive had! on the film. causing raisod section: in such framoecommonly referred to as a "pin cushion" or "biscuit" effect.
1952 Theatre Catalog, 10th Edition, Page 303