I'm writing a piano piece where r.h. is meant to play staccato for a large section. Instead of adding staccato dots to all the notes, it seems simpler to me to state "All staccato" above the staff. But then there's a section where r.h. should revert to play normally, i.e. non-staccato. Is there a specific term I could use, or will stating "non-staccato" do?
If you want to stick to the traditional Italian:
- then you should use sempre stacc. (sempre staccato) for the staccato section. (Some prefer the words in the other order i.e. staccato sempre)
- and then either norm. (normale), or nat. (naturale), or ord. (ordinario) for the non staccato section. It would also probably be fine to just use non stacc. (non staccato).
It's simpler, and clearer, to write the dots. Doesn't matter if it goes on for 20 pages, write the dots. They're part of the notes. You want 100 notes, write 100 notes. They're all staccato, write 100 dots.
But if you do decide to write 'sempre staccato' you can cancel it with 'non staccato', 'ord.' or 'norm.'. Not 'legato'. That's different to just 'not staccato'.
You have a section where the r.h. plays staccato throughout, followed by a section where the r.h. doesn't play staccato. In this case, unless your so-called "section" is extremely short compared to the usual Western music (Pop/rock/jazz/classical/etc.), usually musicians strive for maximal contrast between sections and will play legato, as long as you notate some slurs/phrase marks. Also, because of this, it's natural to have legato for your second section in question, instead of some kind of in-between articulation like mezzo-staccato.
So in my opinion, in the non-staccato section, it would be best to notate the phrases with slurs (a common practice), provided no notes in that part are to played staccato, and notate any extra articulations you want (e.g. tenuto, accents, marcato). If there are a few notes in the non-staccato section you want to be played staccato, mark them staccato, with no slur going over those notes.
Another thing to consider is that legato is often inferred from style or context, not explicitly written. A slur on the violin part simply means the notes have to played in the same bow, and in the absence of any other articulation markings, it would be legato, but not necessarily so when there's e.g. staccato dots as well. On the other hand, distinct slurs following one another need not have audible breaks between them, as is testified by the various classical repertoire and their respective common performance practice.
Essentially what I'm saying is that if you just tell the pianist to not play staccato in the second section, they will most naturally play legato, even though technically you didn't tell them play legato and they could've played mezzo staccato instead for example.