The pads will be installed inside the pad cups and the keys will be mounted onto the instrument. Afterwards the entire instrument will be exposed to high humidity and heat, typically in an oven, with a heat-gun or in a sauna-like room with all keys pressed down onto the instrument. The pad will remold itself to the shape of the tone hole.
This method will leave a big impression on the pad. A large surface will touch the tone hole, at first giving the impression of a good seal. Press padding is typically done in mass production at cost-concerned workshops. It is usually applied to fish skin, bladder or synthetic pads.
The tone hole shaped impression will touch the body on a large surface. Dirt and humidity getting on the pad will prevent the pad from properly closing. An irritating sticky noise is often noticeable. The seal doesnt last very long and the fish skin gets stretched, which also reduces the life expectancy of the pad. The result is a low-quality seal.
The result is often mediocre or at times even bad. The seat in the pad does not last very long. Additionally, fish skin pads can get overstretched, break easily, and are prone to sticking.