Troubleshooting bath bombs

[Nanda]

After my previous thread I got some icing colors and they do work really well! I made vanilla & raspberries and cotton candy bath bombs previously and they turned out great. But then I attempted to do a batch of lavender and another one of magnolia and unfortunately the bath bombs turned out like this:



The lavender color turned blotchy and uneven, with a dark purple ring around the middle and lighter on the top and bottom. I find the color and effect quite pretty but unfortunately they all started cracking.

The magnolia ones developed these weird white dots after they dried, and they have cracked as well, a little more then the lavender.

This is the recipe:

1 cup sodium bicarb
½ cup citric acid
½ cup corn starch
½ cup epsom salts
1 tablespoon kaolin clay
3ml fragrance
icing colorants
95% alcohol to spray with (after previous failed batches with witch hazel)

Why does this happen? The only thing I can think of that I did different from the first batch is that I reused some of the leftovers from the previous bath bombs that were in the bowl. I sifted them every time to remove any clumps.

Also, do you know if it's possible to recycle bath boms? If I have one that crumbles, is it possible to spritz it and mold it again?

Thanks everyone!

 

[lsg]

You might try adding a little melted cocoa butter with the mix. That will make a very hard bath bomb when it dries. Try mixing the colorant and fragrance with the melted cocoa butter first and then mixing that blend with your dry ingredients. You will get a much more even distribution. As for the colors morphing, you will probably have to go with lavender and raspberry colorants that do not morph. Rose clay will give you a subtle rose tint, but not a vibrant color.

 

[Nanda]

Thanks for the advice. I've tried oils previously but I didn't like the ring they left around the tub, but maybe a little cocoa butter won't have this effect.
I can't really pack the bombs too hard due to my molds, otherwise they won't release, so unfortunately they are quite brittle and I'm scared they will crumble during shipping. Will def try the cocoa butter trick, thanks!