This stone is from before 1980 and is glued with Colofonium. See last picture under the stamp.
Between 1980 and 1986 there have been no Coticules produced.
From 1986 to 1998, Burton Rox's did glue non-natural combos with Araldite. It was the intention to get a thin bond line. The coticules were glued to Rouge du Salm. This stone is much redder than the BBW.
After 1998 "Ardennes Coticule" glued non-natural combos with epoxy which has been thickened with a filler.
Henk