The skewing may be due to the scanned newspapers being part of a bound volume. As newspaper issues were intended to be printed and consumed quickly rather than kept and revisited, publishing volumes offered readers a more expensive, lasting edition of the articles. Sometimes, the new volumes would include illustrations. Many digitisers rely on bound volumes of many newspaper issues, as the volume format better preserves them. For the British Library collections, in some cases volumes that were tightly bound have had to be partially disbound and then shrink-wrapped and returned to the shelves in a partially bound condition for microfilming. The physical items are bound in volumes, so there is not a one-to-one relationship between the physical object, containing many issues, and the digital object. For Trove, some state libraries have used formerly bound copies of newspapers, in order to get the best quality for digitisation. The State Library of South Australia disbinds its copies when microfilming, as does the Library of Victoria, or they loosen the bindings during the microfilming process in order to deal with margins and so on. Other digitisers indicate that they do not usually disbind, as it is not usually possible to rebind them, and this threatens the physical object. In those cases, the pages can be harder to read as the binding interferes with the scanning process.