If you read the colour card by Tonna, he says there are no shades of Plum, and is just one colour. I doubt this due to time and air quality over 150 years +.
Peter Fowler

I would like to see your scans of rose red to dark rose red. I have special scanner software where I can quantify the colour in a series of numbers.
Never seen bronze or copper in 50 years of collecting 1d Reds.
Regards
Peter Fowler
pfowler999@talktalk.net

That is a good question. Just joined ,so late with any reply. What was the original gum?
Potato starch? Gelatine if pure is clear in solution. Becomes light yellow with slight impurities. It would only be guess work what effect it had on the colour of the gum and the face of the stamp.

Hi Phil, Thanks for your interest in colour measurement of 1d Reds, mainly C7-C13. I have a very good scanner ,a Epson Perfection 4490. I use SilverFast software to look at and analyse the colours. You can calibrate the scanner using a multi coloured target, before you scan the stamps. It is very co...

As an ex colour matcher in the plastics industry for 11 years I've always been interested in the shades of the perforated 1d Reds. I am working on a method to quantify the colour, rather than ,orange red, give it colour coordinates. Anyone else interested in this subject. What were the colours like ...