Place a coffee filter inside a fine-mesh sieve. Pour cooled bacon fat through sieve into a half-pint or larger glass jar that seals with a tight-fitting lid. Close tightly and shake gently to combine.
Let stand at room temperature for 4 to 6 hours, then freeze for 1 to 2 hours or refrigerate overnight, until fat solidifies and rises to the top. Spoon off as much fat as you can.
Pour bourbon through another coffee-filter-lined sieve to remove remaining solids. Transfer to a clean jar and store in the refrigerator or freezer for up to a month.