For each of four burnt flints from different levels of a Palaeolithic cave site, assessment of the equivalent dose was attempted using normalization of 1st glow peak height by a 2nd glow monitor measurement on each slice. All artificial doses were administered using a ⁶⁰Co gamma-ray source. For any group of slices, all apparently having received the same dose (i.e., archeological, or archaeological plus gamma-ray), the ratio of 1st-to-2nd glow thermoluminescence was not constant but varied by as much as 30%. Investigations into the cause of this non-normalization together with the results of an experiment attempting to simulate the effect are described. -- AATA