"Black Soot" translates as black rust. Comparable to koheln dust - i.e. a greyish black.
With our Milk-Paint it is not necessary to mix an "Extra Bond" (adhesion promoter). However, you should make sure that a primer, such as our Majs Memories "Gesso", is applied before painting. Depending on the size of the project, put the milk paint in a clean container first and only then add the water. TIP: It's better to use a spray bottle so you get a better dosage and don't run the risk of the paint being too thin and having to add more powder. Learning by doing !
Drying time: If possible overnight, because it should be really dry for further processing, e.g. a second colour or other accessories.