Ok guys, and the final answer is:
" <font color="green"> Yes. All Bourbon (including ours) is made using the sour mash process.
Our Rain vodka is made using a sweet mash process and it maybe that we refer to our bourbon making process as sweet mash until the point where we add sour mash.
Hope that clears the mystery up.
I guess that makes sense to call it such until the time the backset is added, but it made for a confusing read on different websites haha.