AIR TRACK SPARK PAPER ROLL WHITE 180mx20mm WIDE
Spare large roll of white paper used on Air Tracks for spark recording. 20mm wide x180m long.
This white paper is wider than the 'Recording Timer' parper and it lies over the spark paper. As a spark is shot through poth papers to earth, a black dot is erupted to the underside of this white paper, thus forming a set of black dots that relate to velocity.