Sealed stainless heat treating bags (.003 thick) with one open end are used to prevent decarburization of the connecting rods during the heat treating process. When the correct time & temperature is reached the entire bag is placed in the hardening oil. Holes are immediately put in the stainless bag to allow the hardening oil to touch the rods. Hardening oil must touch the rods for hardening of the material to take place! After rods reach the temperature of the hardening oil they should be tempered.
