Care and preservation treatment proccess
There is not any one product or any single thing that can be done to a chainsaw carving that will keep it from deteriorating, (drying out, cracking, etc.) but there are any number of things applied together that will significantly delay this deterioration and preserve chainsaw carvings for generations to come.
First and foremost is to keep chainsaw carvings out of the sun, the reason a chainsaw carving cracks is because it dries out too fast, the outer rings of the wood dry and shrink faster than the inside and a crack forms,these are almost unpredictable in where they appear, however there are any number of wood preservation products that can be used to inhibit if not halt the drying proccess altogether, the most effective of which in my experience and belief is to be the oils, tongue oil, danish oil, teak oil, mineral oil, and near the last but not the least, boiled linseed oil, it is also one of the most difficult in the proccess, there are log oils for log cabins, and a product called Cetol by Sikkens.
For the past 3 years I have been using Boiled linseed oil, thinned with mineral spirits, brushed or sprayed on.
Whichever oil is used, please understand for it to be effective, multiple applications are required, thinning with mineral spirits or turpentine helps the oils to soak in.Applications of twice a day for at least a week have shown to stabilize chainsaw carvings.
Sanding Sealers should be used after the oils have had a chance to soak in and dry, at least 1 week but several months might be possible for a very intense treatment proccess, 2 coats.
Finish: Any number of finishes might work, however, the most readily available in my area is Helmsman Spar Urethane by Minwax, it is suitable for indoors or outdoors and is very durable, it however cannot come in contact with moisture before it cures,(at least 24 hrs, up to 48 hrs in cooler conditions) 2 or 3 coats, with a fresh coat once a year for optimum preservation and possibly twice a year in high exposure area,full sun, rain, snow, sleet.
Indoor pieces might not need reapplication for several years and can be dusted and waxed just as furniture, however with the drier indoor air in the winter there is a higher risk of cracking,reportedly humidifiers reduce the risk.