Milky Way soap stamps work in cold-process as well as melt and pour soaps.

For Melt and Pour Soap:

Melt and pour soap base tends to be firmer and more brittle than cold-process soap, and the stamps may consequently require an extra tap or two to register a satisfactory image. If you wish to soften the M&P soap base, add 1-2 ounces water to each pound of base. The stamped images in this softer soap display a smoother, more polished finish. After stamping, age the bars a few days to allow for evaporation of excess water.

For cold process soap:

Depending upon the formulation of your soap, the soap may be ready for stamping as soon as it's unmolded. Softer and/or superfatted soaps may require a few days of aging. The soap should not stick to the stamp; if it does, the soap needs to harden a bit.

Each stamp comes with an instruction sheet.

Dimensions: 1.25 x 1.25" Diameter