Hi, Philippe

Generally everybody use chemical colorant for dyeing a clear canopy ( but I have had no experience).
How to use of the dyes for resin and so on is as follows.

1 Dilute the dyes with water to 5%.
2 Warm the aqueous solution until 60c degree to 80c degree.
3 Dip a canopy to the warmed aqueous solution.
4 Wash away the canopy with neutral detergent.

http://www.osaka-kaseihin.co.jp/syohin.htm

Best regards