Why is my carving cracking
......what should I do / not do?
Cracking (checking) is completely normal and healthy it is natures way of curing wood. If wood did not crack trapped moisture inside a log would eventually cause rot. Therefore it is healthy to provoke minor cracking in order to preserve long term integrity of a carving. Unlike furniture and lumber which is usually 2" or less thick and kiln dried, carvings 10 plus inches thick do require additional time to dry out. Once dried, your carving will have a significant reduction of weight as core moisture is enabled to escape. Some people find cracks contribute to the rustic character of wood while others may find that it compromises their carvings aesthetic integrity. Cracking is also more apparent with painted carvings as opposed to natural carvings as the natural wood color revealed by a crack is contrasted against the paint color. Regardless of which ideal you subscribe to there are indeed measures which can help control excessive cracking. Immediate temperature changes (especially cold to warm) will almost always cause a carving to crack. If positioning a carving indoors during winter months, it is recommended that it is gradually brought up to temperature over several days. During this process it is recommended to position the carving in a progressively warmer temperature. In addition, make sure the carving is NOT positioned near heat ducts, radiators, fireplaces, or anything else that has constant temperature change. One big mistake many carving purchasers make is to immediately apply a urethane sealer. This inhibits the wood from breathing while also trapping core moisture leading to excessive cracking and rot. A marine grade spar urethane should be applied only after a carving is sufficiently dried. As moisture takes the path of gravity, it is important to keep the carving base slightly off the ground. This can be accomplished with small plywood shims, stones, bricks, etc. and will enable moisture from the carving to escape from the bottom while also preventing ground moisture wicking up into the base.
With the above in mind, the most significant factor which prevents cracking is to order your commissioned carving with sufficient lead time.