No, we do not use the term 'wood stain' in Bulgaria. We say ''байц за дърво"

(The crystals I use are sold in hardware stores and the solution is used to stain wood)
I mean, what I use as tools and materials is not specially designed for calligraphy. Few people here are familiar with Western calligraphy and there are no calligraphy supplies.
I would like to ask all of you what kind of gouache you use to write light letters on dark (or black paper). I tried the best brands on Bulgarian market of art supplies (
http://www.trinity4arts.co.uk/pages/gouache.htm) but still the problem is that either the paint is too thick to flow or too thin to leave a visible mark on black paper. Should I use acrylic paints instead?