Which type of curl is secured off its base to add length and volume?

The type of curl that is secured off its base to add length and volume is the full stem curl. This technique involves placing the hair strand away from the scalp, which allows for maximum movement and volume at the roots. It creates a longer stretch from the scalp, leading to a softer, more dynamic curl that can provide a substantial amount of body and volume.

Full stem curls are particularly effective for styles that require lift and texture, making them a popular choice in various hair designs. When the hair is wrapped further from the base, it results in a curl that has a more voluminous appearance, as the root area remains more relaxed compared to tighter curl techniques.

Other options involve either placing curls at or closer to the scalp (like the base curl and half stem curl), which results in different curl characteristics and volume. Rollers can also create various types of curls depending on their placement and the way they are secured, but the defining feature of a full stem curl is that it is distinctly off the base to maximize volume and length.