Thanks Freek, interesting to know that they mix it in the shop to make the proper colour. That was not entirely clear from the sikkens leaflet.
In the meantime I bough one can of Beoro Biowood lasure teak : no that perfect : – too watery (one liter covers 20 sq meter .vs. 15 for Cetol thus each layer is too thin ; – the taint is very slightly darker than my original light teak (not a problem), – the taint is not homogeneously mixed with the liquid leaving darker marks along brush directions, those marks have to be brushed over and over in order to rub them out.
I’ll have a try at Cetol mixed to my own colours.