Metric weights used for weighing ingredients using a Class A balance should be handled with?

When using a Class A balance to weigh ingredients, it is critical to maintain the integrity and precision of the metric weights to ensure accurate measurements. Handling these weights with forceps is the appropriate method because it minimizes the risk of contamination from skin oils and moisture that can affect the weight.

Using forceps allows for a controlled and careful handling of the weights, ensuring that they remain clean, dry, and free from outside influences that may alter their mass. Additionally, this approach prevents any direct contact that could lead to wear or damage to the weights, further preserving their calibration and reliability for accurate measurements in a laboratory or pharmacy setting.

Other methods like using water or oil could introduce additional mass or residue that would weigh on the balance, thus skewing results. Using fingers can transfer oils and moisture, which could also affect the weights. Therefore, forceps are specifically designed for this task, making them the suitable choice for handling metric weights in precision applications.