A page on my Australian Glass blog discusses Rob Knottenbelt's production ware from the period after he left the Jam Factory in late 1977 and before he set up his studio Britannia Creek Glass at Wesburn, Vic, in 1984. These items are identified by some characteristic shared features and by the maker's mark on the base in the form of a small scratched arrow pointing radially out.
http://australianglass.blogspot.com/2015/09/robert-knottenbelts-early-production.htmlRob Knottenbelt has featured in several other entries on Glass Messages, including some earlier works from his Jam Factory days
here and
here, while a much later BCG production ware item is shown
here.
Trevor