==Misunderstanding== 
 It's possible that a commercial supplier (given as a citation in the article) has used the name of Atramentum, the most prominent meaning of which is an historic varnishing technique,  as a "trade name" for one of his products. The characteristics of this modern product have now supplanted the traditional meaning in the article. I'll try to sort this out in due course, but any clarification from other editors, using non-commercial sources, would be very welcome.