The weakness of British semi-chrome leathers may result partly from faults in the curing or vegetable tannage done elsewhere and partly from the re-tanning processes themselves. Important are: a) the amount of vegetable tan retained after stripping; b) the amount of chromium fixed by the leather; c) the basicity of the chrome tannage; and d) the type of fat-liquoring oil used. Leathers involving all 16 possible combinations were produced and tested for thickness, area, tensile strength, elongation at break, buckle-tear strength, compressibility modulus, water penetration pressure, shrinkage temperature, and grease content of the grain layer and of the middle split. Only changes in chrome content gave appreciable changes of strength. The higher amount of chrome reduced the strength. It also increased water repellency in samples tanned in basic liquor, in those which were lightly stripped, and in those fat-liquored with oil containing relatively little of the sulphated component. Shrinkage temperature was raised in leathers that contained more chrome, by basic tannage, and by relatively thorough stripping of the vegetable tan.