I think that is a nice piece of work there. It gets the point across and clearly explains what needs to be done.
Obviously, the amount of information included will depend on the level of knowledge the reader has. In this case, as you stated, you assumed the reader knows a fair bit. Including more info, makes the description usable by a wider number of readers. At some point though (as you expand your audience), this turns into a book about screenprinting (if you have to start at zero).
Another very important tidbit. . . The reader and writer have to be on the same page with regards to the vocabulary. Definitions might have to be brought up if there is any uncertainty or possibility of not knowing/misunderstanding. Ability to communicate effectively is predicated on having the same vocabulary and same meaning for the same words! Any new terminology or concepts have to be explained with the preexisting, already clear, vocabulary and concepts.
pierre