How hard capsules are made and not suitable for liquids.

Soft v's Hard Capsules Soft v's Hard Capsules

The Melbourne Food Depot sells one type of capsule in two varieties and many sizes.
The capsule of choice is the hard style capsule. These are the only ones customers can fill and seal themselves. For ease of explanation I will describe the gelatin manufacturing process. It is exactly the same for vegetable capsules just substitute HPMC for gelatin.

The Manufacture of hard gelatin capsules consists of the dipping of stainless steel pins (dyes) into a gelatin solution, drying, stripping from the pins into a collate, trimming of the caps and bodies, and joining together for shipment. The strength, flexibility and movability of the gelatin allow the manufacture of various sizes, colors and designs for assuring a snap closure after filling. The hard gelatin capsules are not suitable for filling with liquid. No consumer level capsules are designed to be filled with liquids. The reason why is contained below.

Soft Gelatin Capsules are not available for sale from the Food Depot because this style of capsule is required to be formed, filled and sealed in one continuous motion. This hermetically sealing process is not possible in a domestic setting. The gelatin in this style of capsule is plasticized with propylene glycol, sorbitol or glycerin. The soft gelatin encapsulation process begins with the formation of two ribbons from a molten gelatin, each of which is passed over a die of the desired capsule size and shape. At the point where the two rotating dies meet, the capsule is formed and filled with the active ingredient.