Blue Oil-Based Premium Stamp Refill Ink by BCH for Pre-Inked Rubber Gel Pads & Dot Matrix Ribbons - 20 ml -0.68oz

There are two kinds of stamps: self-inking stamps- which you add ink by yourself. These inks are usually water-based. The second type is pre-inked stamps. These inks are generally oil-based. Again, check with the manufacturer and make sure which type your stamp uses.
General Instruction
The oil-based ink will be absorbed into either rubber or sponges. The process is a lot slower than water-based ink. However, the ink is designed to last a long time in the open air, so be patient. You will either find an absorbent rubber or refill sponge in your equipment. For example, if you work on a typewriter ribbon that doesn't have those, the ink needs to be absorbed by the whole ribbon. If your stamp doesn't have a refill sponge, like in the video below, you can drill a hole and create a cavity to fill the ink and let the ink be absorbed over time.

GREAT VALUE. Replenish these for a fraction of the cost of new ones: foam ink pads, felt pads, pre-inked stamps, oil-based print ribbons.
NON-TOXIC. Oil-based, low odor, skin-safe and environment-friendly.
DURABLE AND PERMANENT CRISP AND CLEAR PRINTS. Waterproof after drying. Outdoor-Grade weatherproof. None-fading. Made of sturdy pigment polymer resin, it doesn't fade under direct sunlight.
EASY APPLICATION. Put few drops of ink on a dried stamp pad. Works with most pre-inked stamps if your stamp is "nonrefillable" Google search Jfp307xBlmA.
MULTI-USE. The ink can also be applied to Dot Matrix Printers. Google "Dot Matrix Ribbon Refill BCH Oil Based"