Dry cooperage is also employed to construct cylinder shapes such as columns that are not intended to contain anything at all. White cooperage using white woods such as basswood, beech and poplar made tighter barrels than the dry cooper but much lighter duty than the wet cooper. White coopers made butter churns, sugar buckets, washing tubs and other household and farmstead containers. Cooperage refers to the joining of boards with angles on their edges to form a cylinder, usually with a top and bottom, called heads, held together with bands of wood or metal. These containers can be in an indefinite number of shapes from large hogsheads or pipes capable of containing hundreds of gallons of liquid to small, coopered personal canteens of a couple of gills. A straight cylinder is relatively easy to make, with 8 pieces cut with 22 ½° on both long edges, this will fit together to form a circle or cylinder with joints that butt together. If you have 9 pieces the angle will be 20°, 10 pieces will be 18°. Each stave or board needs to have a bevel cut on its edge equal to the total number of staves times two divided into 360°. Angle=360°/2x#staves. Columns are usually coopered together and glued to form a more stable and stronger construction rather than being made of solid wood. Barrels are cylinders that taper in at each end. A tub is wider at the top than the bottom and a firkin is a tub with a larger bottom and a smaller top.
Cooperage measurements of the period:
Gill 1/4 pint
Pint 4 gills
Quart 2 pints
Gallon 4 quarts
Firkin 6 ½ to 9 gallons
Rundlet 18 gallons
Keg 30 gallons
Hogshead 52-63 gallons
2 hogsheads 1 Pipe
2 pipes 1 Tun
1 Tun 252 gallons
1 Butt cask from 108-140 gallons
Peck 2 gallons
Bushel 8 gallons - 4 peck
36 Bushels 1 Cauldron
4 Firkins 1 Barrel - 26 to 36 gallons
Kilderkin ½ barrel or Cask
I will describe the method of making a wet coopered barrel in white oak and the techniques are the same for dry cooperage, but the materials and tolerances are different. Splits of sufficient length to make the barrel are selected. Because the material is going to be bent, splits are preferred to saw cut staves as the grain runs from end to end. Using a shaving horse to secure the split, the wood is hollowed out on the inside of the stave with a scorp, inshave or jigger to make the concave inner surface of the stave. The grain selection is for the wood in the barrel to be oriented the same way as it grows in nature with the outside out. This also begins the shape that the stave will eventually have. It is reversed and the outside is made convex using a drawknife to taper the edges. The ends are tapered more to form the staves closer to the shape they will have after they have been bent. The hollow on the inside and the roundness on the outside bring a uniform thickness to each stave, which makes bending easier and produces a better barrel. This is only rough out work, smoothing will be done after the tapers and bevels are cut. The taper is done with a coopers carving axe. This small offset broadax head with a short handle is used to taper the staves as well as rough out the heads. A block or stock knife can also be used for this purpose.
With the tapers formed the stave is taken to the joiner where the edges are smoothed up and the proper bevel added to both sides of each stave. An experienced cooper will produce a good stave almost every time. Remember these staves have curved sides with a slight bow and the bevel must match the next and every other stave and this must be calculated so that after the staves are bent, everything fits. The inside of the stave is more finished than the outside. The outside is finished after the barrel is hooped up and it is more difficult to finish the inside but tools are made for that purpose. The cooper uses many tools that are familiar to the average woodworker but these tools have a twist or curve.
The coopers joiner plane is the largest hand plane. From three to 4 feet long with a 4-inch or wider blade these tools were used inverted, many with legs on the front to form an inclined workbench with a blade. Some without legs were rested on small benches and the cooper would pass the staves over the blade to form the bevel on the edge. Patterns for various sizes of barrels were common in many cooperages but a veteran cooper seldom needed to use a pattern except for the initial sizing. The shape of the pattern determined the bulge of the barrel. The reason that barrels are doubled tapered is that they have much greater strength than if they had straight sides. The tension and compression that the barrels are under also increases their strength and the pressures can be exerted from outside and within and the barrels will take the stress.
Once enough staves have been made it is time for assembly and this is when an extra person with two more hands can come in handy. Trying to get all of those staves to stand on end can be a real busy time. Many coopers use a short, somewhat larger tub or partial barrel in which to stack all of the staves to help hold them in their approximate position. Stout assembly hoops, usually made of riveted hickory are used to gather and hold all of the staves into position. A hoop driver is used to force the hoop down on the barrel; a mallet will also work on the larger assembly hoops. Once one end is secured with a hoop or two, and cooperages would have many assembly hoops of different sizes for different barrel sizes as well as groups of hoops each slightly smaller than the next to drive all of the staves together at various locations on the bulging barrel, the barrel is inverted. With all of the staves at the loose end splayed out from each other, the trick here is to bring them all together. This is accomplished with a ratcheted windlass for larger barrels or a Dutch Hand for smaller work.
These tools use ropes to encircle the splayed staves and as the windlass is tightened it pulls the staves together allowing an assembly hoop to be driven over the gathered staves. The Dutch hand is a stick with offset holes through which a rope is looped. By pressing down on the end of the Dutch hand the rope is tightened around the barrel and a hoop is driven on. Most barrel staves require heat and steam to facilitate bending the strong white oak staves. A fire is built in a small metal framework called a cresset and the inside of the barrel is soaked with water. This will be converted to steam by the fire and helps prevent the barrel from catching on fire. Some barrels are intentionally charred on the inside but this is done after it has been completed. The barrel is placed over the fire in the cresset and the inside of the barrel is heated. Water is applied with a rag on a stick as necessary to keep the barrel from charring. As the staves heat up they become softer and capable of being bent with the windlass or Dutch hand. They are then secured with assembly hoops and placed aside to dry and set.
As the barrel is drying the heads can be made for the ends of the barrel. Heads are butt joined boards held with dowels. The strength is added when it is in the barrel and as the wood swells this simple joint works just fine. It was indeed a poor cooper that had to flag his heads. This was a practice of inserting cat tail leaves or flags in the butt joint, they would swell up when wet making a leaking head tight, was considered rough work, a properly joined head of white oak would be tight and not leak. The joints were said to pinch a hair. Rectangular boards of different sizes are selected for the heads, just enough wood to make a circle. Some coopers join the edges and then drill for dowels the head is then shaped either by rough sawing or chopping the head to a circle after it is inscribed with a compass. The heads are made after the barrels and the compass is set to the proper diameter and the additional size for the fit into the head is added to insure a tight fit. To determine the size of the head a compass is used to inscribe 6 equal steps around the inside of the croze. With the compass set to inscribe 6 equal distances it will be the proper radius to describe a circle that will fit the barrel perfectly. A compass plane with an arched body with the sole on the concave side of the arc rides around the rough head forming a circle. The grain changes directions and is worked from both sides from the side grain towards the end grain. A flat plane is used to make a chamfered edge on both the inside and outside of the head and to flatten both sides of the head at the joints and bringing it to a uniform thickness. The chamfered edge is like a raised panel in a framed rail and style door. This feathered chamfer will fit into a dado around the inside of the barrel at each end an inch or two from the ends with a croze and the dado is called a croze. Back to the barrel.
Once the barrel has dried and set it can be prepared to receive the heads after several steps. First the staves are brought to uniform length by planing the end grain with a sun plane. Like a compass plane the sun plane has an arched body but the sole is flat. This curved sole rides on the circular top of the barrel and planes the ends flat. The inside is also smoothed at the joints with a buzz, a handled scraper with a convex base and scraper blade secured with a wedge. The insides have been previously shaped and the buzz just smoothes out the joints. A specialty tool called a howel is used to form a concave depression around the head of the barrel down a couple of inches from the top. Made of wood it is a fenced hand plane that rides on the end of the barrel and extends down into the inside of the barrel. The convex blade cuts as the fence keeps it uniform from the end. The howel is re-adjusted and the top chamfer can also be cut with this tool. Some coopers use a chamfer knife, a slightly convex spokeshave or a jigger to cut this chamfer. See Drawknives, Scorps, Jiggers and Inshaves. At the bottom of the howel, a saw kerf the width of the end of the chamfer is cut using a tool called a croze. The teeth are sharpened to cross cut and set to cut just the proper depth and a fence keeps it tracking at the bottom of the howel to produce a dado to accept the head.
Attention can now be turned to the outside of the barrel and then the heads can be set. Some of the assembly hoops are removed, but not all, the barrel is under tension and the outside of the barrel is finished with a spokeshave or flat bottomed buzz to scrape the barrels smooth. The hoops are moved around to work on all areas on the outside of the barrel, working from the bulge towards the ends. When the outside is finished the final permanent metal or wood hoops are fitted to the barrel. A tool called a traveler, a wooden or metal wheel in a handle with a known outside diameter is rolled around the outside of the barrel at the hoop location and the measurement is transferred to the metal hoop which is cut, bent and riveted to the final shape. Wooden hoops overlap and are secured with notches on their edges that interlock with corresponding notches on the other end. Saplings are sometimes used, split in half with the bark on or removed and the flat side of the split is placed against the barrel. The hoop closest to the bulge is called the bung hoop and the hoop closest the head is the head hoop or headband. The number of hoops is determined by the size and strength requirements. Some bands are held with L shaped hoop nails, most are held with friction. Some bands are heated and driven on the barrels and the slight tapered is formed as it is driven on. If any scorching happens the bands are removed and the char scraped and the bands or hoops driven back into position. Hoop drivers some all metal some with wooden handles have flat faces that can drive the thin hoops down on the barrels.
The headbands are removed and the ends spring out slightly, just enough to allow the head to be slipped into the end of the barrel. The chamfer helps as does the howel and the head is worked until it is in position. Coopers usually have a few special tools with flat blades or hooks to help position the head into position. Barrels usually have one wide stave into which the bunghole is drilled at the apex of the bulge. The grain of the wood of the top head of the barrel is lined up with the bunghole on the barrel. The bottom head is placed in the bottom with the grain running at 90° to the top head. Once the heads are in place the head hoops are driven back into position. Rosin is rubbed on the inside of the bands before they are driven on to the barrel for the final time. Another bunghole is drilled in the centerboard of the head near the bottom end of the head. The hole is drilled and then tapered to accept the bung or cork. Many coopers would brand or stamp their work and mark the capacity.
Dry cooperage is much like wet cooperage except the materials like basswood are much easier to work and fire is not necessary for bending while some soak the barrels before bending the staves. Wire was sometimes used for hoops and saplings like witch hazel, willow, river birch and hickory or splits of ash, oak and hickory were also used for both wet and dry cooperage. Some dry barrels have just a croze for the head and forgo the howel and some heads are thin enough not to require chamfering on their edges. Barrels for gunpowder were always made without metal hoops to prevent an accidental spark from igniting the contents producing an unpleasantness.
Barrels have much greater strength than other containers and heavy ones could be rolled by one man, unlike a large chest or crate that had to be lifted and carried by several. Most early commodities were packaged and shipped in barrels. Barrels could also be re-used for other purposes and many were taken apart the metal and wood reused and many staves staved off the cold in a warm fire. Barrel bands show up as hardware in early pioneer and settlement furniture especially in the West. Native Americans turned them into arrowheads, hide scrapers and other tools of everyday life. Much of the early commerce in this country was conducted on barrelheads, convenient flat places to do business. It was cash on the barrelhead. So early entrepreneurs always had their customers over a barrel. Remember always keep your heads up.
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