Decanting

Decanting is the method in which a player combines partially full potions of the same kind to produce one full potion and one partially empty potion. For example, decanting a potion containing 3 doses and another containing 2 doses yields one full potion (4 doses) and one partially full potion (1 dose). Potions can be decanted by Bob Barter who is found at the Grand Exchange. He can be right-clicked to speed up the process. This process will also make potion sales easier because most players tend to buy full potions more. Also, if you want to save room, you can buy an even amount of potions (2,4,6,8,10,e.t.c.) and make 2 [2] potions turn into 1 [4] potion.

Decanting is also easier for players that make potions, so instead of using a potion on another to fill one up, they can just go to Bob Barter and save a few clicks. Also at the Grand Exchange as of the 24th Novemebr 2010 update, Bob will also decant noted potions.

Zahur in Nardah will turn four dose potions into three dose potions for fifty gold pieces per inventory.

Due to an update, the money-making potential of decanting has subsided, but there are ways of making money; one way is to buy strength potion (3)s at median price, decant them into strength potion (4)s, and then sell the strength potion (4)s at maximum price on the GE. This method only works when strength potion (4)s are selling at (or close to) max price, which they often are. Now it is highly rare to find a good potion to decant to make a profit.

Some potions, such as a strength potions, will lose you money if you are not careful, although super attack potions are capable of bringing in a sizeable profit.