Hollow form is a term typically applied to turned objects that narrow toward the top and that are hollowed out inside to a uniform wall thickness. Hollow forms allow the wood turner to explore and create a greater range of freeform shapes that can exhibit the grain and detail of particular areas and orientations within the tree.
There are two "nerve racking" periods in creating a hollow form. The first occurs during the initial phase of turning the external surface, during which there is an ongoing decision about the ultimate shape of the hollow form, and whether cutting a bit deeper will better display the unique character of a particular piece of wood (remembering always that once a layer of wood has been removed, it can't be put back). The second challenge presents in the hollowing phase. How thin to make the walls? If the wall is thin enough, the wood can flex during the differential shrinking that is an aspect of the drying process. The flexing will usually prevent the wood from cracking and may subtly alter the shape, as if allowing Nature to have a hand in its creation. A woodturner takes pride in the skill of turning the walls very thin, and in hollow forms it is even more difficult to create thin walls. But, trying to turn thin walls presents a risk. A mere fraction of a second of distraction, and the cutting tool can pierce the wall, or even shatter the object.The more beautiful and carefully crafted the outside was, the more regrettable and embarrassing is such a slip-up.
Click on the images to see them in detail (including species of wood and dimensions of the piece).
Ash Hollow Form - Diameter: 6 3/4 inches, Height: 11 1/8 inches (A46)
Plum Hollow Form - Diameter: 4 1/4 inches, Height: 4 1/4 inches (F86)
Plum Hollow Form - Diameter: 3 1/2 inches, Height: 7 1/2 inches (F147)
Pine Hollow Form - Diameter: 8 inches, Height: 11 inches (G22)
Birch Hollow Form - Diameter: 6 7/8 inches, Height: 7 1/4 inches (J40)
Pine Hollow Form - Diameter: 12 5/8 inches, Height: 10 inches (G25)
Plum Hollow Form - Diameter: 6 5/8 inches, Height: 10 inches (B38)
Douglas Fir Hollow Form - Diameter: 5 1/2 inches, Height: 10 1/4 inches (D2
Plum Natural Edge Hollow Form - Diameter: 7 1/2 inches, Height: 4 1/2 inches (F85)
Douglas Fir Hollow Form - Diameter: 5 3/4 inches, Height: 8 1/2 inches (D4)
Cryptomeria Japonica Hollow Form - Diameter: 3 7/8 inches, Height: 4 3/4 inches Weight: 1 oz (28 gm) (F33)
Elm Hollow Form - Diameter: 3 1/8 inches, Height: 7 1/8 inches (C46)
Elm Hollow Form - Diameter: 4 3/8 inches, Height: 8 3/4 inches (C47)
Elm Hollow Form - Diameter: 6 1/4 inches, Height: 9 3/4 inches (C49)
Birch Hollow Form - Diameter: 5 inches, Height: 4 1/2 inches (J43)
Elm Hollow Form - Diameter: 7 1/8 Height: 8 3/4 (C51)
Elm Hollow Form - Diameter: 9 inches, Height: 7 inches (C52)
Willow Hollow Form - Diameter: 5 1/16 inches, Height: 6 3/4 inches (C71)
Willow Hollow Form - Diameter: 7 1/2 inches, Height: 6 1/8 inches (C73)
Willow Hollow Form - Diameter: 6 inches, H: 12 1/4 inches (C77)
Willow Hollow Form - Diameter: 8 3/8 inches, Height: 12 7/8 inches (C78)
Willow Hollow Form - Diameter: 6 inches, Height: 14 1/4 inches (C79)
Willow Hollow Form - Diameter: 6 inches, Height: 14 1/4 inches (C79)
Cryptomeria Japonica Hollow Form - Diameter: 4 1/8 inches, Height: 8 1/4 inches (F7)
Maple Hollow Form - Diameter: 7 1/2 inches, Height: 3 3/4 inches (B6)
Sycamore Hollow Form - Diameter: 9 inches, Height: 7 1/8 inches (F15)
Plum Hollow Form - Diameter: 4 1/4 inches, Height: 10 1/8 inches (F25)
Pine Hollow Form - Diameter: 8 1/2 inches, Height: 9 1/8 inches (G19)
Maple Hollow Form - Diameter: 5 3/8 inches, Height: 7 3/8 inches (F31)
Maple Hollow Form - Diameter: 7 1/4 inches, Height: 15 1/4 inches (B7)
Maple Hollow Form - Diameter: 6 1/4 inches, Height: 15 11/16 inches (B8)
Birch Hollow Form - Diameter: 6 3/4 inches, Height: 8 1/2 inches (J37)
Maple Hollow Form - Diameter: 7 inches, Height: 15 3/8 inches (B9)
Maple Hollow Form - Diameter: 6 3/8 inches, Height: 11 3/4 inches (B10)
Maple Hollow Form - Diameter: 9 1/2 inches, Height: 5 7/8 inches (D13)
Pussy Willow Hollow Form - Diameter: 6 1/2 inches, Height: 2 1/2 inches (B25)
Pussy Willow Hollow Form - Diameter: 4 1/8 inches, Height: 9 1/2 inches (B27)
Cherry Hollow Form - Diameter: 5 3/8 inches, Height: 4 1/8 inches (A77)
Iron Bark Eucalyptus Natural Edge Hollow Form - Diameter: 5 3/4 inches, Height: 4 3/4 inches (A92)
Cryptomeria Japonica Hollow Form with Walnut Finial - Diameter: 7 5/8 inches, Height: 5 1/2 inches (F35)
Black Locust Hollow Form - Diameter: 4 3/3 inches, Height: 6 1/4 inches (B51)
Black Locust Hollow Form - Diameter: 4 inches, Height: 7 inches (B50)
Diameter: 8 3/4 inches, Height: 8 5/8 inches (B59)
Black Locust Hollow Form - Diameter: 3 3/4 inches, Height: 10 1/4 inches (B89)
Birch Hollow Form - Diameter: 14 1/2 inches, Height: 8 1/2 inches (J44)
Maple Hollow Form - Diameter: 4 3/4 inches, Height: 14 1/8 inches (D32)
Black Locust Hollow Form - Diameter: 5 1/4 inches, Height: 8 5/8 inches (K51)
Black Locust Hollow Form - Diameter: 4 7/8 inches, Height: 12 1/8 inches (K53)
Pine Hollow Form - Diameter: 6 1/4 inches, Height: 9 inches (G43)
Pine Hollow Form - Diameter: 8 1/8 inches, Height: 14 7/8 inches (G45)
Madrone Natural Edge Hollow Form - Diameter: 2 1/4 inches, Height: 4 inches (C138)
Maple Hollow Form - Diameter: 5 7/8 inches, Height: 12 1/4 inches (D59)
Black Locust Hollow Form - Diameter: 4 5/8 inches, Height: 6 inches (D94)
Laburnum Hollow Form - Diameter: 4 1/4 inches, Height: 3 inches (B97)
Black Locust Hollow Form - Diameter: 6 1/8 inches, Height: 8 3/4 inches (D100)
Black Locust Hollow Form -Diameter: 3 5/8 inches, Height: 7 3/4 inches (D101)
Black Locust Nartural Edge Hollow Form - Diameter: 5 7/8 inches, Height: 3 5/8 inches (D103)
Diameter: 4 3/8 inches, Height: 8 inches (D121)
Plum Hollow Form - Diameter: 2 1/4 inches, Height: 7 inches (D124)
Birch Hollow Form - Diameter: 8 inches, Height: 15 1/8 inches (J32)
Birch Hollow Form - Diameter: 7 1/8 inches, Height: 10 1/8 inches (J33)
