Prior to filming, a comprehensive set of bibliographic checks is carried out. This information gathered is presented at the start and throughout the film, providing the user with important details about the collection being filmed. We check for incorrect dates, incorrect pagination, missing pages and issues. It is also important to keep an accurate page count to ensure the run fits neatly onto the reel of film.

To ensure that the best possible image is filmed, a number of processes may be carried out. The most common is the ironing of papers to produce an even and flat surface. Special care must be taken when preparing old or damaged material. We often recommend that tightly bound volumes are dis-bound to provide the best possible image. We have staff who have been trained within the NLS Bindery who can disbind volumes. The NLS can supply archival storage boxes on our behalf.

Where necessary, we also repair and clean material prior to filming. Pencil marks, soot or newsprint stains can be gently removed using special document cleaning pads. Small tears are fixed using archival Document Repair Tape. If the material is badly damaged, we have a close working relationship with Tom Valentine Ltd at the Carronvale Bindery, who can provide expert repair work.

The SNMU has four microfilming cameras. These consist of three purpose built Gratek models for filming large newspapers, and a recently acquired Congress multi-purpose camera ideal for filming smaller newspapers, manuscripts, etc.

In many ways, the darkroom is the engine room of the SNMU. It houses the processing and duplicating equipment.

Processing has a strong influence on the quality of a microfilm. The film passes through a series of chemical solutions and washes, which must be kept constant to avoid fluctuations in the density of images on the processed films.

Resolution can be defined as the clarity of the image on the film. Resolution is checked by filming test charts and examining them through a microscope.

The image on the film must be of the highest quality because as each generation is duplicated clarity is lost. This is increasingly important as we film with scanning to an electronic file in mind.

Like resolution, density has a profound effect on the quality of the microfilm, and a film with poor density will get worse as it is duplicated.

Density checking determines an optimum exposure range for a given camera / processing set-up. A test page is filmed repeatedly with the lamp voltage being increased incrementally for each exposure, and the ideal density reading is selected.

After the film has been processed and before duplicating it has to pass through a vigorous checking procedure. As the film passes through each check, details are recorded on a checking sheet to ensure that our high standards are maintained. Only when we are satisfied that the film is of the highest possible quality is it passed to be duplicated.

Duplicating Film

A Working Negative is made from the Master Negative, from which the Working Positive Copy is then made. This is the microfilm that is sent to our customers. Further copies can be made from the Working Negative, which is stored here at the SNMU. The Master Negative is stored on our behalf at the Causewayside building of the NLS.