One of the drawbacks of using a separating funnel is emulsions can form easily, and can take a long time to separate once formed. They are often formed while liquids are being mixed in the separating funnel. This can occur when small droplets are suspended in an aqueous solution. If an emulsion is formed, one technique used to separate the liquids is to slowly swirl the solution in the separating funnel. If the emulsion is not separated by this process, a small amount of saturated saline solution is added ("salting out").
Research is being done on alternative, more efficient techniques, mostly utilizing stir bars (stirrer bars) to decrease or even eliminate the chance of emulsification, thus decreasing the amount of waiting time.