PURPOSE: To obtain the titled composition uniformly colored without foaming in strand, having excellent mechanical properties, by adding a specific amount of a metallic oxide in blending polyacetal polymer with carbon black.

CONSTITUTION: 100pts.wt. composition prepared by mixing polyacetal polymer with 1W75wt.% carbon black (e.g. furnace black) is blended with 0.001W2pts.wt. metallic oxide (e.g. oxide of calcium or magnesium) or metallic carbonate (e.g. carbonate of calcium or magnesium).