I've been thinking about the following pattern for some time:
Linseed oil... soaks into the (visible and microscopic) pores
When I was a kid, this wasn't the way I was taught to use parentheses: they go after an idea, and explain it further. Yet it makes perfect sense--"visible and microscopic" is an aside, explaining details.
Is this the right punctuation? Is it informal, or only acceptable in technical writing? My gut says brackets might be more correct, but I can't justify it:
Linseed oil... soaks into the [visible and microscopic] pores