Some bath bomb questions

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Alyssa McF

New Member
May 13, 2018
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I took a class on making bath bombs and have a recipe, but have a few random questions:

1. If it's easier to get my hands on "regular" epsom salts instead of the "fine" kind, can I just buzz the epsom salts in a food processor to make them fine grained?

2. If it's true that it is better to use glycerin based dyes instead of water based dyes as a colorant for bath bombs (so they don't fizz while due is being added), can I make my own by mixing food coloring or other dyes with glycerin, and what ratio of glycerin to dye would you use?

3. How long would you keep your bath bomb in the mold before taking it out? In class we only kept them in the mold long enough to press them together, then since we needed to same mold to make another, we had to take them out right away. This worked ok, except some of my bath bombs separated into two parts (it was a two part round steel mold). Then I read somewhere else you have to leave them in for hours. What's the general consensus on this (if there is one?)

Thank you!
Hello and welcome.

I can’t help you with the epsom salt but I do know that grinding salt can make sharp edges. It may not make a difference in. Bath bombs as the salts should dissolve.

I use micas or powdered dyes for bath bombs. I’ve never used nor would I use food coloring.

I only leave mine in the molds for a little while to dry a bit then remove.
Thanks for your reply.
I use micas or powdered dyes for bath bombs. I’ve never used nor would I use food coloring.
Do you find that the micas or powdered dyes leave a ring in the tub? Or do you use something like Polysorbate 80 to prevent that?
I don’t use any Epsom salts in mine (I’m in FL and they never harden) and I also only use mica (yes mix with poly 80)
I used to make a lot of bath bombs, have not made them lately, but here is my opinion.

Q1: Personally I do not put Epson salt in my recipe. I have used the coarse one as a decoration on the top of one, when I color them. I don't see why not you can you found to fine the one you have. I still will watch out not to put too much in the BB. Generally the BB are not made with Epson salts. Can you tell me what is your recipe?

Q2: NO NO NO! I would NOT, as in never use glycerin based color. Only use water base soap colors (even the ones at the craft stores that are water based, or lakes I would use. The first time I made a BB, I used a glycerin base color, and I spent 3 days cleaning the tub. It was horrible. Even regular micas can stick unless you add poly80. My recommendation is to only use water based color, or micas that dissolve in water.

Q3: You can press them at put them aside to dry or cure as soon as you mold. But that is easy to achieve only with stainless steel molds IMO. If you use the plastic ones, I would leave them in the mold for 2+ days (depending on the weather, or where you live). Then take them aside, and leave them undisturbed for at least a week, so they can harden. I see people using them tight away. Nothing wrong with that. But if you want the ones like they sell at the stores, they do take time to harden. What kind of mold are you using?
Recipe is
2 cups baking soda
1 cup citric acid
1 cup corn starch
1 cup epsom salts
(combine all dry ingredients)
6 T. almond oil
3 T. water
1 tsp. fragrance
(combine wet ingredients, then add to dry ingredients)
Then add:
1 tsp. SLSA
1 T. Polysorbate 80
add micas, lakes, la bomb colorants, to preference

This worked well for me when I did it in the class and the bombs worked well in the tub.

I'm in Seattle, WA so it's a dryer climate actually.