Abstract: Wood which is relatively poorer in connection with its ability to resist weathering, rotting, insect attack, etc., is made more resistant to such factors by a two-step process. The first step is to impregnate the poorer quality wood with an aqueous solution of tannin extract taken from a plant species which has superior weathering and other resistance properties. The wood treated with the tannin extract is then further treated with an aqueous solution of a fixative to prevent leaching of the extract during use of the wood, e.g., in exterior applications. The process of the present invention not only results in preservation of the wood, but can also be used for purposes of coloring the initial wood product. Abundant and relatively cheap woods can then be converted into wood products having qualities more closely like those of more expensive woods. In addition to the above-noted advantages, the present invention also uses treating substances which are non-hazardous and which are not damaging to the environment.