Hi, Soapchick ... I've tried loads of different ways to do this ...
1 Grated M&P opaque and whipped it without melting it (the heat of the beaters melted it for me!). Result took so long to dry that I nearly lost the will to live;
2 Next I melted opaque M&P in the microwave then whipped it ... OK, but cooled down too fast and went claggy;
3 Melted opaque M&P (microwave) and added some hot water (about 4 or 5 tablespoons to about 150grams of soap). Result was the same as 2;
4 Melted M&P over a saucepan of very hot water, added a few tabelspoons of hot water and about half a teaspoon of glycerine to the melted stuff and whipped it without taking it off the heat. Result was OK, to begin with, but it shrank dreadfully and went sort of 'rubbery';
5 Hallelujah!! Melted M&P over the saucepan of v hot water. Once it was melted, chucked a bit of cold water into the saucepan (not the soap!!) to cool the water down a bit, then whipped the soap until it looked like cream, without adding any water. (Add FO before you melt it). Have your piping bag ready to fill, and work fast!
Nice thing about this method (5) is that if it sets in the piping bag or nozzle, just throw it back in the bowl and whip it again until it behaves. You might need to add a tiny bit of water to free it up if you're 'rewhipping'. This is the only method I use now; it behaves beautifully and dries incredibly quickly to a lovely firm surface. I've made a Christmas cake soap with a deep layer of this whipped soap on top, and it cuts perfectly. It's firm enough to be able to wrap the slices in cling film without the topping smearing, as well.
File comment: Slice of cake in cling fim!
Christmas Cake 4.jpg [ 17.44 KiB | Viewed 30307 times ]
Hope this helps! I have to admit I've never tried adding oil, but reckon that now I've found a simple solution I'll stick to it. For the cake in the picture I just smeared the whipped topping all over it, and spread it with a knife dipped in hot water ... keeping the whipped mixture hot seems to be the secret.