We are seeing more and more tapes effected by mould. Mould growth is encouraged by warm damp conditions. The spores eat in to the oxide coating on the tape and in really bad cases cause the tape to stick to itself. Whilst we do endevour to clean and transfer mouldy tapes it is not always possible. Extreme tapes and tapes where the tape is sticking to itself may be unrepairable. Also note that even if we do make a transfer the picture quality is often degraded.