What is the necessary condition for the surface before making an exothermic connection to steel?

In order to make an effective exothermic connection to steel, the surface must be cleaned to bare steel and free of any contaminants. This is crucial because contaminants like rust, dirt, grease, or any oxidation layer can inhibit the conductivity required for a successful exothermic reaction. Such connections rely on the electrical conductivity and thermal properties of the raw steel to ensure a strong bond and minimize resistance, which is necessary for both safety and performance.

When the steel is properly cleaned, the exothermic reaction can occur without interruption, leading to a more robust and reliable connection. This condition ensures that the heat generated during the reaction can effectively fuse the materials together, creating a strong and durable connection capable of withstanding the stresses of the environment in which it operates.

Other conditions like being free of grease, dried completely, or painted with a protective coat, while important in their own contexts, do not address the essential requirement of fully exposing the bare steel surface to facilitate an optimal exothermic reaction.