Discussion - Member to Member Sales - Research Center
Discussion - Member to Member Sales - Research Center
Seemingly, only copies supplied by the Crown Agents to dealers in the UK escaped this deterioration. Perhaps others that were quickly exported to a low humidity climate also fared better.
The seller of this block provided an explanation of the reason for gum tropicalisation as part of his description. Here is is, with a few tweaks to aid readability:
Left side marginal block of 4 from the left pane, R7/1 - 2, R8/1 - 2, with R8/1 G clipped at right and broken. Superb gum for the issue; this stamp normally has dark streaky gum, and a comparison block is shown in the scans. This block obviously was supplied by the crown agents to a U/K dealer and thus was not subjected to the climatic extremes of the colony, hence its cream, very lightly streaked gum as supplied by the printers.
The change in colour of the gum in early issues when subjected to extreme climatic conditions was due to the addition of a small quantity of glucose to the gum to make it more flexible. As gum arabic on its own flaked off when dry, the glucose had the effect of making the gum "wetter" and hygroscopic (able to hold a tiny percentage of water, thus preventing it drying out totally). So the sheets, after being gummed, were dried under hot air blowers which caused the glucose to caramalise. Once in tropical conditions, this process continued and the "cooking process" continued unabated, resulting in the dark streaky gum normally associated with tropical Colonies.
Do the statements shown in blue 'hold water',
in your view? 
Login to Like
this post
Some time ago I looked at a Hong Kong KGVI $10 block of four, listed on eBay. This was an 'exceptional' block. Exceptional in the true sense of the word; the block did not exhibit the usual badly toned (tropicalised) gum associated with the 1938 issued definitives that were sold and kept in the colony.
Seemingly, only copies supplied by the Crown Agents to dealers in the UK escaped this deterioration. Perhaps others that were quickly exported to a low humidity climate also fared better.
The seller of this block provided an explanation of the reason for gum tropicalisation as part of his description. Here is is, with a few tweaks to aid readability:
Left side marginal block of 4 from the left pane, R7/1 - 2, R8/1 - 2, with R8/1 G clipped at right and broken. Superb gum for the issue; this stamp normally has dark streaky gum, and a comparison block is shown in the scans. This block obviously was supplied by the crown agents to a U/K dealer and thus was not subjected to the climatic extremes of the colony, hence its cream, very lightly streaked gum as supplied by the printers.
The change in colour of the gum in early issues when subjected to extreme climatic conditions was due to the addition of a small quantity of glucose to the gum to make it more flexible. As gum arabic on its own flaked off when dry, the glucose had the effect of making the gum "wetter" and hygroscopic (able to hold a tiny percentage of water, thus preventing it drying out totally). So the sheets, after being gummed, were dried under hot air blowers which caused the glucose to caramalise. Once in tropical conditions, this process continued and the "cooking process" continued unabated, resulting in the dark streaky gum normally associated with tropical Colonies.
Do the statements shown in blue 'hold water', in your view?
Login to Like
this post