Many of these bowls are turned from green, that is unseasoned, wood. Such wood is selected because it will distort; how it distorts depends on how the grain is aligned within the bowl.  A bowl turned from seasoned wood will remain round and distort only slightly with seasonal or geographical changes in humidity.

Most of my bowls are made to be used and will look and feel better for it. I use an oil and beeswax finish that provides a good base for a variety of patinas. If any wood salad bowl, plate, platter or chopping board is in daily use, you can hand-wash it in hot water and detergent and set it on a drainer to dry. I've included several photos of bowls and plates that have been used for years.

If you prefer a shiny, more antique, patina you need to polish the wood regularly with a wax polish. The old rule of thumb is every day for a week, then once a month. After a few months your wood glows like a cherished antique. A patina like this cannot be applied from a bottle: it is the result of on-going care. Regularly polishing will enhance any surface.

Pin oak, 510mm diameter, green turned, 2008

Tripod foot on an oak bowl turned green

Casuarina salad bowl, turned green with a rounded base. 2010
 Osage orange, 2009

 Ebonized and limed oak, 400mm diameter, 2007

Tripod base of the bowl at left.
Redgum, claret ash, 2007

Redgum, 2003
Tasmanian blackwood, 200mm diameter, 2001

Charred ash, 200mm diameter, 2008

 Myrtle Bowl 2003: 400mm dia

Nesting Tasmanian Myrtle Bowls, 2009

Salad Bowls

African Blackwood 150mm dia. 1979
Redgum, 400mm dia.

Box Elder

Holly, elm, voamboana, elm burl, 150-230mm diameter;  turned 1978-80 and well used since then.
 Osage orange, stringybark, maple, huon pine, 170-200mm diameter; turned 1983-85 and well used since then.
Ash salad bowl, used since 1978

 Voamboana, 170mm diameter, 1978

 Plum, 160mm diameter, 1979

 Laburnum, 180mm diameter, 1980