How can users properly cover the cup lid when using a 9oz coffee paper cup to avoid leakage?

Before use, you must carefully check the match between the cup lid and the cup mouth. The standard cup mouth diameter of this 9oz coffee paper cup is 8 inches, and you must use a matching cup lid designed specifically for this size. First, take out the cup lid and check whether there is a clear size mark on the edge, such as "8oz/9oz" or "20.3cm". Gently place the cup lid on the cup mouth and observe whether it fits naturally, paying special attention to whether the sealing ring on the inside of the cup lid is intact. If the cup lid is found to be deformed, cracked, or warped at the edge, it should be replaced with a new cup lid immediately, because these defects will seriously affect the sealing performance. It is important to note that the wrong use of a cup lid of a mismatched size such as 10oz, or the reuse of an old cup lid that has lost its elasticity, will lead to a poor seal. Cup lids that are deformed by pressure during transportation are also not recommended.

Controlling the liquid level of coffee is an important prerequisite for preventing leakage. After professional testing, the safe liquid level of this 9oz paper cup should be controlled at 0.5-1 cm from the cup mouth. In actual operation, it is recommended to use a standard measuring cup to accurately pour 240-260ml of coffee. When viewed from the side, the inner wall of the cup mouth should be clearly visible, which means that enough space has been reserved. For drinks with more foam, such as cappuccino, more space needs to be reserved. Hot drinks also need to consider the thermal expansion and contraction effect. It is recommended to reserve at least 1 cm of space. Professional baristas can use a coffee machine with a scale to accurately control the amount of cups, strictly implement the "90% full" standard in take-out orders, and remind customers that full cups are prone to leakage during transportation.

Correct alignment operation is a key step to ensure sealing. This cup lid is usually designed with a precise positioning buckle or guide groove structure. In specific operation, first keep the cup upright and stable, and hold the cup body with both hands. Align the guide mark of the cup lid with a specific position of the cup mouth, usually the seam of the cup or the logo mark. Then tilt the cup lid at an angle of about 30 degrees, let the guide groove first snap into the edge of the cup mouth, and then slowly rotate the cup lid until it completely covers the cup mouth. During this process, pay attention to the touch of snapping into place, usually there is a slight "click" feedback. If you use a cup lid with a silicone seal, make sure the seal fits the edge of the cup mouth completely without folding or twisting.

After completing the initial cover, you need to press and seal it comprehensively. This step requires the use of both hands: hold the cup body with your left hand, press the center of the cup lid with moderate force with your right hand, and then press the 12 o'clock, 3 o'clock, 6 o'clock and 9 o'clock positions in a clockwise direction. Each pressing point should be maintained for 2-3 seconds to ensure that the pressure is fully transmitted. For cup lids with locking mechanisms, after completing the circular pressing, you need to apply additional pressure at the locking position. The pressing force should be moderate. Too light will result in insufficient sealing, and too heavy may cause the cup lid to deform. Professional baristas can teach customers to use the "thumb circle pressing method": use the thumb and index finger to form a ring and apply even pressure from the edge of the cup lid to the center. After you have finished pressing, you can wipe it with a clean paper towel to check for signs of leakage.