If you have a true log cabin, you might want to preserve the rustic character of the interior of the log walls. You could leave them to darken naturally over time or apply a stain or clear finish to enhance the color and texture of the logs. Another option would be to whitewash the walls. You'll need to understand the qualities of whitewash, however, before using it inside any home.
Whitewash, also called calcimine or lime paint, is a low-cost paint made from lime and chalk. Thinned with water, it forms a thick, white coating that hardens as it reacts to carbon dioxide in the atmosphere. Whitewash is appreciated for more than its low cost. It forms a durable coating that breaths, allowing water vapor to exit a structure. The finish is chalky and rubs off when touched.
Famous for its use in Tom Sawyer's fence painting adventure, whitewash has been around for centuries. It's useful not only for fencing, but also for exterior wood and masonry surfaces. Because its chalky surface rubs off on clothing, it was not typically used inside when other finishes were available. In poor households, however, it was often the only affordable option for interior painting.
Flat latex paint is an alternative if the chalkiness of whitewash turns you off. Some homeowners thin the paint to create a nearly transparent quality. Latex paint that uses chalk to simulate the dry, chalky appearance of whitewash is often available at paint stores and from mail-order suppliers.
The interior logs of log houses are often left to darken naturally over time. Popular, too, is the use of a clear finish to impart a glossy or dull sheen to the timbers. A penetrating wood preservative prevents oxidation and preserves the color of new logs.