Use at 5% to 8% of total volume.
Use caution with this product.
Add it to your eliquid carefully and follow the directions. There is a big difference between drinking a Coke or a can of Red Bull and adding e-caffeine to your e-liquid. Different delivery mechanisms to the blood stream means different volumes allowed.
The best approach is to count drops.
Because only tiny amounts will be used, trying to measure in a pipette or other device is not accurate enough. Drops, on the other hand, are consistent and easily controlled.
Calculate your drops as follows: 25 drops per ML
10 ML Bottle Size = 250 Total Drops
5% of 250 amounts to 12.5 drops. If you have a full bottle of eliquid, add 12 or 13 drops of e-caffeine to end up with roughly 5% of total volume.
30ML Bottle Size = 750 Total Drops
5% of 750 amounts to 37.5 drops. If you have a full bottle of eliquid, add 37 or 38 drops of e-caffeine to end up with roughly 5% of total volume.
It seems like a lot of counting, but in reality it only takes a minute. If you are careful to squeeze the bottle very gently you'll find the drops dispense in an even and controllable fashion.