Chemical preservation of robinia is required only where the surface is exposed as a decorative feature, where the wood is in contact with the ground or with water, or where sapwood is present. Poplar for exterior use should always be impregnated; false heartwood can be impregnated within 32 hours; vacuum impregnation is possible. Turkey oak is regarded as non-durable but can be used in building away from (or just touching) the ground, exposed to the weather, after simple preservative treatments. With proper preservation these species can be substituted for softwood in many applications. -- AATA