I recently came across this YouTube video: "How to equip home made PCBs with a professional looking stopping agent (solder resist layer)" <
http://www.youtube.com/watch?v=VNYIVZgbi9M>.
What is this film that he's using, and where can I get some?
(There is a link in the comments section of the video, but the site it points to is in German, and for some reason further comments have been disabled.)