Technology Monroe Fluid Semisynthetic Cutting & Grinding Fluid for CNC Milling, Drilling, Tapping, and Turning, Astro-Cut B 5 Gallon Pail. Around 20% mineral oil makes up the semi-synthetic general purpose metalworking coolant ASTRO-CUT B. This substance, when diluted with water, creates a translucent amber emulsion that provides great cooling, high lubricity, and excellent workpiece visibility. Except for magnesium, almost all metals may be machined and ground using ASTRO-CUT B, which was created without the use of chlorine, phenols, nitrites, or DCHA. All metalworking processes, including CNC milling, turning, drilling, tapping, and grinding, are compatible with ASTRO-CUT B.