In my assortment of barrels 2x 2L, 5L, 15L (maybe closer to 16-17L) I have tried a few things:
2L barrels I used the cheapest port I could find and regretted it, left the port in for 6 months because I didn't get around to distilling enough to fill them until then, and even the 2nd fill of scotch (DWWG + green packet whiskey essence, first fill once had 40% and the other 65%, second & third fills are at 65%) has come out with a ?tartiness (best way to describe it) on the front of the tongue when aged for 3 months. Both are currently on their 3rd refill of the same and I plan on getting rid of them once this batch is done. It was these size barrels I discovered that filling them to the brim caused a leak when putting the bung back in (insert physics mumbo jumbo about air compresses but liquid doesn't when not in a vacuum or something)
5L barrel I already made a post about (
viewtopic.php?f=22&t=10025 ) but the short version is to prepare your barrel with water first to minimise losses and it was filled with a Bourbon (TPW + still spirits american & tennesse whiskey essences) for 6 months, there was about a 50% loss and to me seemed over oaked. I recruited some more taste buds who gave it nothing but praise, maybe they aren't as picky as me? As for refill I put in 4.45L (still some air gap) of single malt (DWWG + still spirits black single malt essence @ 65%) and is due to come out start of april.
15L barrel was filled with the same cheap nasty port for about 4 months, was then swapped for bundaberg rum for about 6 months and finally filled with Scotch (40% TPW + green still spirits whiskey essence) for 12 months. This drop is simply AMAZING! I can't remember exactly how much I filled the barrel with, but I got out of it 18 x 700mL bottles and this has sold me on the idea that bigger barrels @ longer times = much better spirits. Refilled with 15.75L (still had room for maybe another litre?) with Single Malt (DWWG + still spirits black single malt essence @65%) and will be due Australia day next year (you can be sure there will be a sneaky tasting on xmas day this year!).
I hope this helps with people who are looking at both smaller barrels for aging plus aging neutrals with essences added to them. My ambition is to be making all grain single malt whisky by the end of this year. I was nearly going to add this to another current barrel thread but decided it might be taking it off topic a bit.