History for KWZ El Dorado

KWZ El Dorado comes in 60 ml bottles, produced in Poland. The ink has a smell of vanilla, but is not labelled as scented. The scent evaporates quickly from the paper.
El Dorado is a yellow ink which deepens to orange, even reddish orange in big drops. It has a good amount of shading, and is well-lubricated. There can be some nib-crud on a pen if it is left alone for too many days, which is easily wiped off.