Tape stock made with polyester can develop a condition known as "sticky shed syndrome". This condition occurs when the oxidation of the tape sticks to the magnetic heads of the playback machine. The oxidation builds up a dirty residue on the heads as playback continues. This shedding creates distortion to the original sound of the recording often referred to as separation or shed loss resulting in very low volume levels and "fuzzy" sounding inaudible audio. When sticky shed is apparent, baking the tape in a convection oven at varying temperatures and durations, according to the dimensions of that particular tape, can help to get an optimal pass off of the tape for preservation. This technique, however, could permanently damage the original tape and the preservation re-recording pass should be made within a 24 to 48 hour time frame.