Melt the soap (I'm melting about 16 oz. here) in your measuring cup. However, once it's melted, you need to let it cool to about 120 degrees. If you pour it onto the chunks while it's still very hot, you will cause the chunks to melt some and bleed color into the white overpour. (Not an entirely undesirable effect - but not the one I wanted for these bars.)
Here, I'm cooling the soap base in a water bath in the sink.
