#1978
Author: Charles A. Bishop, C.A.Bishop Consulting Ltd.
Email: CABishopConsulting@cabuk1.co.uk
Subject:
One of the common tests for curvature is to lay out a long length of web that is under no tension and compare it to a straightedge. We used to do this on the night shift using a corridor in the factory that had a highly polished floor (less friction). We could lay out somewhere around 50yds of the roll and fairly close to the corridor wall. By measuring the distance of the edge of the web at each end to the wall & the edge at the centre to the wall it was possible to tell how much curvature the roll had.
Similarly looking at the web without tension would also give some indication if it was able to lie flat or if it was baggy, contained cockled edges, evidence of stretch, chicken wire, etc.
All films are likely to contain some defects but many are at levels that will not affect the subsequent processing. The magnitude of the defects needs to be measured & now using a digital cameras can be photographed & recorded. What you set as acceptable limits will depend on what you intend to film to be used for & what may have already been agreed with your supplier.
Charles A. Bishop
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