After taking apart a barrel you'll have a pair of heads that aren't used at all in making the chair. There are a number of things you can do with them, and making a serving tray is the simplest (it's also the starting point for everything else you'd do with a head). To do this build, you'll need a couple hours and the following materials and tools:
- Barrel head
- Wood glue
- Sander with various grits of paper
- Clamps, preferably including one large enough to fit the whole head.
- Prying implement (if the head pieces are stubbornly stuck together).
Glue the head togetherThe basic idea here is what you'd expect. Most barrel heads will easily fall apart if you pull at them, and that's no good if you want to build anything out of it. (Some are held together pretty rigidly, if you have one that doesn't want to come apart you'll need to go a different route for strengthening it, such as putting a board underneath it). So you'll want to glue it together. There are plenty of good write-ups online for doing this (here's the one I used), so I'll just add a few tips.
Before starting, check out your heads with a long straight-edge. Check across the pieces individually and also across all of them. Some heads just won't be very flat. You can fix it somewhat if the pieces want to fold in on themselves, but if the pieces themselves aren't flat there's obviously not a lot you can do, unless you own a belt-sander or similar. If you're trying to make a table or something else where flatness is pretty important, use the flatter one for that. The serving tray doesn't need to be very flat, and mine isn't.
After you've taken apart the head, check the interior joints for leftover wheat paste. It's what they use to help maintain a seal, but it'll interfere with the wood glue. I used a knife and a screwdriver to fish it all out of the various nooks and crannies before gluing my barrel heads.
When gluing the pieces together I found it easiest to glue them one at a time, starting from the middle and working my way out. I also clamped each piece lightly to a 2x4 before clamping the pieces together, to help keep things flat. I found that if you just naively clamped the pieces together they wanted to bend pretty badly, but this will likely depend on the head. Once the pieces are clamped set a timer for half an hour (or whatever your glue's drying time is) and come back to do the other pieces later.
Sand and finishOnce everything is all glued up, you'll want to sand it smooth. Do a first pass to clean up the gunk (now including glue) with a higher grit, making sure to hit all the edges so they're not sharp. Afterward keep sanding it with finer grits until it's adequately smooth. For the serving tray I went up to 200-grit, for a table I stopped at around 150.
Now you'll just want to finish it. For the tray I used some Boos mineral oil that we already had on hand, since it's food-safe cutting board oil, which seemed ideal. The various other types of food-grade waxes and oils would work as well. For a table (or other piece of furniture) you'd want to use the appropriate finish for the location, I used the Penofin for my outdoor table and a Danish oil on the indoor table.