A laboratory method for evaluating wood preservatives should provide in a comparatively short time an integrated measure of the relative permanence and fungus-inhibiting capacity of a product. There is as yet no generally acceptable laboratory method of this type. Systematic service records serve to bolster the reputation of established preservatives. Accelerated field tests provide a basis for recognizing new preservatives. However, if it were not for basic technical information, supplied through laboratory experiments, changes in specifications which might further improve such preservatives are delayed. Furthermore, the development of new and promising preservative materials is retarded if evaluation must depend entirely on years of service. Such retardation complicates the consumer's problem of procuring suitable substitute preservatives when material shortages arise during emergencies. The object of this paper is to evaluate the agar-block and soil-block methods for testing treated blocks, both before and after weathering of the test specimens, with particular emphasis on oil-type preservatives. The presentation and discussion will show the modifications in technique developed by other published and unpublished work on the soil-block method carried on either simultaneously or since the tests in question were completed. Lines along which current and future work are developing to resolve controversial problems will be indicated.