John
Did you see the packaging? Are we sure that the mortar used on site and claimed to be supplied by a proprietary patching compound manufacturer was indeed manufactured by said proprietary patching compound manufacturer?
Maybe, in the best (?) traditions of subcontracting, an alternative no-name brand label material was substituted in the interests of subsidising the post-prandial consumption of liquid or gaseous addictive compounds by staff and workers alike.
Stirring the mortar mix down under.
david