A few thoughts: Why does everyone think it’s so hard to melt sodium cocoyl isethionate (SCI)? If you pick the right version and couple it with the right surfactant – disodium laureth sulfosuccinate, cocamidopropyl betaine, cocamidopropyl hydroxysultaine (more about that one soon…), sodium methyl cocoyl or oleoyl taurate, sodium cocoyl glutamate (more on that soon, or read about it now in my new e-zine) and others, which you can read about in the link for SCI.
Make up a double boiler – I use a fondue pot, but you can use a pot on the stove – and get the water boiling. Use as much water as you can without having it spill over the sides when you add the SCI container.
Reduce the heat so it’s not splashing into the container, add your SCI and other surfactant ONLY in a glass container, and heat until melted. If you’re using prills, it should only take 5 to 10 minutes at the most. If you’re using noodles, it might take longer. If you’re using powder, it isn’t necessary to heat it at all!
What you see in this picture is the powdered SCI we used to make shampoo bars at Windy Point Soap in Calgary last weekend. We made these without heat as they dissolve nicely in room temperature surfactants. This version was done with C14-16 olefin sulfonate (Bioterge AS-40) and SLSa, and they turned out pretty wonderfully!
I’ve made shampoo and bubble bath bars with this powdered SCI on my own, in classes in Calgary, and with youth at our groups, and every time they turned out awesome!
When they are solid and have a day to cure, I can drop them from waist height!
What can you do if you don’t have the powdered kind and have to heat it?
Make a powdered version by putting your SCI in a coffee grinder.
Ensure you’re using a surfactant that helps it melt well. See the list above and in the linked post about SCI above.
Use loads of hot water in your double boiler. The higher up the sides you can get it, the better, as the part that isn’t touching water will end up cooling down to the ambient temperature. You don’t want the water to be roiling so it gets into your container, but you can have it quite hot. I generally have mine on 300˚F setting on my electric fondue pot’s control dial.
Have fun formulating!