Australian Stamp Gutter Strips, Blocks & Pairs
Marginal markings on stamp sheet selvedges were originally used to aid the printer by showing the colours used in the printing of the stamps. These markings in the pre-decimal era were normally guillotined off. With the changes in printing techniques including the greater range of colours and and double pane printing marginal markings were increasingly left in place.
Later there is probably some doubt the markings had any longer any practical use in aiding printing and were mainly used to deface stamp size gutters in order to stop them being used fraudently.
Gutter are now used as decorative friezes to enhance stamp issues and to add to the number of philatelic items in an issue and special gutter sheets are printed for this purpose! Nonetheless, they can be attractive additions, especially to a thematic collection, and are very collectable.
Used by an electronic device to position the web of paper in each printing unit to ensure that the colours are printed in the correct position. These are usually found etched in the top selvedge for horizontal stamps and on the left for vertical stamps. Bars were also included in the gutters between the stamps themselves in order to "deface" the space that could potentially be used fraudulently. Autotron bars were mainly in issues of the 1960s and 1970s.
Autotron bars are usually collected in blocks of 4, showing the gutter and bars in the left or top margin depending on the format of the stamps.
In 1975 tonal wedges were introduced as a new type of defacement. The wedges are blocks of colour showing decreasing density of the dot pattern, in most cases the colours used for printing.
Tonal wedges are usually collected in strips with 10 stamps either side of the margin showing the complete wedge.
Offset litho stamps carry two main types of marginal markings, colour control circles and Heidelberg strips. Neither had any practical purpose beyond defacement but do provide useful information on the colours used in the printing.
Early colour control circles, from the Leigh-Mardon printings, are usually 5.7mm diameter cicles in the gutter showing each colour used in the printing probably in the order in which they were printed, ending in black. They are usually opposite each pair of stamps and repeated five times.
In the 1988 Living Together series the circles were 4.25mm for the Leigh-Mardon printings and 5mm for the CPE printings. Apart from this issue CPE Australia usually used Heidelberg gutter strips (see below) but colour control circles were also used by SNP Cambec, usually at 5mm diameter.
Colour control circles can be collected in gutter strips or pairs
Heidelberg Gutter Strips are a series of coloured bars and notations arranged in in a specific sequence along the length of the sheet. These look very technical and can be interpreted but again it is likely they had no practical use.
As the strip extended the length of the sheet and the sheets were guillotined into three "Post Office" sheets before being sold there are three variations of strips to be found (Sheets A, B and C) for each issue.
Colour targets are boxed "target" style markings in each printing colour, which are of the type normally removed before issue. Only one issue has these markings, the "First Australian" Bicentennial stamps of 1984, as gutter defacements and there use was never repeated.
From 1995 issues began to appear showing decorative or pictorial symbols and friezes in the margins. These symbols are on the theme of the stamps and add a decorative element to a collection. A number of issues have blank margins particularly the Note Printing issues and the Bicentennial issues from 1986 to 1988.