How to handle Ink consumption part of which evaporates during process

We have a scenario where a particular type of ink is used during manufacturing (we have EBS Process Manufacturing 12.2 implemented). Around 20% of the ink issued to a batch is evaporated. As per the Audit request we are asked to track the wastage due to evaporation. Right now we have set that up as a by product and wastage is booked there during production completion. It also helps in batch balancing in terms of inputs + Wastage = Output (in Kg)

The issue is that this leads to on hand stock of the ink which is not there physically.

Any idea on how to handle this scenario..