I love the concept of solid bath products. I just don’t love adding SLS to my bath. It’s not because I believe SLS causes cancer. In fact, I don’t believe that. It’s only that SLS can be a drying agent and dry skin means wrinkled skin and wrinkled skin means that I look older than I want to look. So, I try to avoid SLS based bath products for fear of old wrinkly skin. I am a woman. I am vain.
I thought about bath fizzies. I thought about non-SLS lathering agents. Presto Changeo! Let’s combine the two!
I made a typical bath bomb:
2 parts baking soda
1 part citric acid
fragrance, color, witch hazel for moisture
(click here for more instructions on making bath fizzies)
I made the bath fizzy mixture and filled the molds 3/4 full. I popped the fizzies out and filled the bottom of the same fizzy mold with 1/4″ of melt and pour. I dropped the bath bomb into the melted soap and gasped as the fizzy started to fizz. 
I poured the remaining melt and pour over the exposed fizzy and looked on, horrified as the fizzy kept on fizzing.
After 2 minutes, the fizzy stopped making bubbles and turned into a poofy, strange, hard mass of … bathtime delight?
The hybrid fizzy didn’t work as well as I hoped. It expended its energy in about 21 seconds. 
But, it bubbled like crazy! Sadly the bubbles lasted for only a few minutes but really, how long does the attention span of most children last?It left a bit of detritus – bits of melt and pour, oils and sludge. I suspect that a better mix might be 15% melt and pour and 85% bath fizzy mixture.
Sigh. One more failed experiment. But every failure leads me closer to the perfect recipe.
D’oh! I didn’t even think about the water content in the M&P. I do know that if I add melted cocoa butter when it’s too hot that it will set off the reaction too.
I’ve never had a problem working with SLeS, but I’ve always had a dust mask handy and send everyone else out of the room when I’m working with it.
I suspect it was the moisture content in the MP that made the fizz start, rather than the heat but I definitely might be wrong.
SLeS is difficult to work with as well as the SLS but you are right, it does have a much better reputation than straight SLS.
The SL sulfoacetate is hard to work with even wearing a mask….inhaling it is BRUTAL! Great product, just hell on the lungs…..
AM, good for you for trying. I am just writing a post that talks about formulating flops. I don’t share the photos. They were too awful…. 🙁
Have you tried using Sodium Lauryl Sulfoacetate instead of Sodium Lauryl Sulfate? I find that it’s much kinder on the skin since the molocules are too big to break the skin barrier.
If not, maybe going with a liquid soap base instead of M&P? The heat of the melted M&P might be what is setting off the fizz.
Thanks for the sympathy!
Oh boy……
I did this same experiment about a year ago! I know your disapointment when the fizzing starts.