I want to be able to access some wav files in a folder outside of pd, so I am using the declare object in order to make my patch able to see that folder [declare -path absolute-path]. Then I want to access directly the recordings with a message like [open rec-1.wav(, but it doesn't work. What am I missing here?

@Kosmas I think that unfortunately [readsf~] only looks in either a relative path to the canvas or an absolute path. The way to do this is to create the appropriate absolute path from your relative path.
The easiest way to do this in vanilla is probably with $1 in a message box:

[symbol rec-1.wav(
|
[open /my/absolute/path/$1(
|

edit: it seems like [declare] should work for [readsf~] but doesn't; might be a bug..
edit2: https://github.com/pure-data/pure-data/issues/234