On the recovery of fibres by tape lifts, tape scanning, and manual isolation.

The recovery of fibre traces via tape lifting, tape scanning and manual isolation is investigated. The recovery efficiency of taping was determined using different tapes, donor textiles, and receptor textiles. It was determined that tape lifts generally recover over 90% of extraneous fibres that had been transferred by direct contact with a donor textile. The recovery via tape scanning was evaluated by the preparation of a set of 15 tapes that contained a number of target fibres on a background of other fibres. The tapes presented varying difficulty and were investigated by trained fibre examiners. The examiners were asked to locate the target fibres and to provide their opinion on the difficulty of the search. As expected, the efficiency decreases for more difficult searches. It was determined that the efficiency of the search was influenced by the microscopic illumination modes used by the examiner. A final experiment investigated the recovery by manual isolation of fibres from non-textile items. It was determined that all fibres from tie cables and knives were recovered, except in those cases where the recipient item contained many fibres. In addition, the examiners correctly sampled each of three fibre populations present on a sample of duct tape.