I got inspired by a YouTube video where the person rebatched or handmilled their soap.  I thought I'd try again.  I shredded up a bunch of old soaps and used my slow cooker.  I shredded up 2 lb 4 oz of soap which was all at least a couple of months old.  I think throughout the cook I added 5/8 cup of water. 

I wonder if the slow cooker dries out the soap too much.  I think it was cooking for 3 hours before most of the chunks were melted.  As soon as I started to glop into the mold it was hardening up.  I even preheated the mold so that the soap wouldn't be hitting a cold mold.  But still I had to really glop and push into the mold.  This batch I kept to fruity smelling soaps and I added satsuma FO to it. 

I still have more soaps that I could rebatch, I have some more with bakery type scents that I could melt together.  Maybe I'll try using more water next time.  I just don't want to add too much water, then it will take longer to dry out.  Got to find that balance. 

So upon thinking about what might have gone wrong with the soap cake and what to change for next time I make a soap cake…

1. The soap cake patties popped out of the silicone mold and were smooth as glass.  Actually really pretty, but probably too slick for this purpose.  The surface was too slick for the frosting to stick well.
1a. Next time, rough up the surface: scratch it up with a fork or something.  Like in pottery, scoring the edges before sticking them together. 

2. Gelling, I didn't make any particular effort to gel the soap cake. 
2a.  Warm the oven up to do CPOP.  Gelling will allow the old soap patties to heat up and hopefully meld better to the new soap. 

3. The soap cake is really HUGE, well at least to me.  5lb of oils/butters or 7lbs total weight.  I had a hard time deciding on color and fragrance for such a large amount of soap.
3a. Maybe next time I'll just use a log mold that holds one or two pounds, cut the soap log down the center laterally to make two thinner rectangular patties and make, not a round cake, but a rectangular cake.  I could still frost it, but it would be a smaller cake and the slices would be rectangular/square rather than wedges which seems more of a challenge to use in the shower. 

So in the end I had put the cake in the oven mostly unsliced.  The next day I pulled it out and sliced it all up.  The layers were still separating, probably because the cake as a whole didn't heat up enough. 

I then put the cut up slices back into the oven at 170 for 2-3 hours again.  This time the layers seem to be better stuck.

I think that the cake layers will darken more.  But we shall see. 

These are really large slices! They are each over 6 oz.