Which hair straightening technique involves using a thermal pressing comb twice on each side of the hair shaft to remove all curl?

The technique that involves using a thermal pressing comb twice on each side of the hair shaft to remove all curl is indeed known as a hard press. This method is designed for hair that has a significant amount of curl or wave, ensuring that the hair is completely straightened to achieve a sleek, smooth finish.

A hard press uses higher heat and stronger pressure than other pressing techniques, making it effective for very textured or curly hair types. This technique is ideal for clients looking for a long-lasting straight look that eliminates almost all curl, often necessary for styling purposes or for specific hair designs.

Other options represent different levels of straightening with varying amounts of curl left in the hair. For instance, a medium press typically involves one pass with the comb on each side, which leaves some texture in the hair, while a soft press may only involve minimal heat and pressure, preserving more of the curl. The smooth press, on the other hand, is not a standard term in the context of professional hair pressing techniques.