Assemble all of your ingredients, materials, and equipment (including your notebook) before you start. Make sure that your knife, measuring cup, and cutting board are clean and free of any dirt. The soap will pick it up and it will be hard to get out.
Prepare the soap mold by lightly coating the inside surfaces with vegetable oil or petroleum jelly, so that the soap will release easily when cooled.
Place the glass measuring cup onto the scale and zero out the weight. Cut the soap base into small chunks and place them into the measuring cup until you have the amount of soap that your mold will hold (a few tenths of an ounce under or over will not matter).
Cover the measuring cup with plastic wrap and heat the soap in the microwave for 30 seconds on High. Remove the soap and stir. It will be a thin liquid with chunks in it. Heat the soap base again, checking it every 10 seconds. After several 10 sec. melting intervals, remove the soap and stir gently to completely melt any remaining pieces of soap. Be careful! Most soap bases will be about 150-160 degrees when completely melted.
While the soap is heating, measure your fragrance out. A good starting place is .25 oz (or 1 1/2 teaspoons) of fragrance oil per pound of soap. You can go up or down from there for a stronger or weaker scent (maximum amount of fragrance being 1 Tablespoon per pound of soap). Once you have measured your fragrance and removed the soap form the microwave, slowly add the fragrance to the melted soap base and gently stir to completely incorporate the fragrance.
If you want to add some color to your soap, (that’s purely personal preference) you can use soap-safe colorants, micas, or natural colorants. Place a little bit of colorant into the soap and gently stir to completely blend the color; remember you can always add more, but you cannot take away. Don’t stir too hard or you’ll get bubbles in the soap. (NOTE: When colorants are placed in a white soap base the end result will be more pastel in color.) If your soap has started to solidify at this time, you can gently reheat it to re-melt it.
Slowly pour the soap into the mold. Try not to splash the soap or get too many bubbles. If bubbles do appear, lightly spray the tops of the bars with rubbing alcohol. You’re done for now! Carefully move the molds to a safe place (or leave them where they are) and start cleaning up. The soap should be hard enough to un-mold in approximately 2 hours (or longer if the mold is larger). You can hurry this process along by putting the mold in the refrigerator, but don’t put it into the freezer! It will take several hours on the counter or approximately an hour in the refrigerator for the soap to completely cool and harden.
While you’re waiting for the soap to harden, write your results in your notebook. How much soap base did you melt? How many drops of color did you use? How much fragrance did you use? Did you have any soap base left over? Did the fragrance seem strong enough? What fragrance did you use? Etcetera. These are notes that will help you duplicate the results next time or remember not to repeat mistakes you made this time.
When the soap is completely hardened, you should be able to pop the bars out of the mold. Some molds will release easily; some will be more difficult. Tapping the mold firmly with the palm of your hand or a large spoon sometimes helps. For a really persistent bar, you can turn the mold over and run hot water over the back of it. The soap should fall easily out of the mold. You can rub off or trim any imperfections with a cloth or a small knife. Since the melt ‘n’ pour soap base is already cured, there’s no waiting. You can use it right away! If it is not going to be used right away or given as a gift, it should be wrapped in plastic wrap so that it won’t lose its moisture.