Hi Azsweets,
I just signed up on this site and noticed your post. If you use a microwave the ivory soap will expand becuase hte soap had many air pockets. I used the double broiler method and it worked great:
Get a double broiler or a large pot and fill with enough water so that a small pot can float and fit with the lid of the bigger pot on (avoids the need to put something in the bottom to prevent the smaller pot from touching the bottom).
While the water is boiling, grate 1 lb of soap finely and add 1tbsp of milk or spray with a little water. You won't need to much liquid because water condenses on the lid and drips into the soap.
When the water has boiled, add the soap and cover, lower the heat to low. It should take about 10 min to turn to mash potato consistency. Check about every 5 min and stir.
This worked perfectly for me!
Hope this helps.
Q
Double boiler soap melting
Q