Bath bombs are one of those things that everyone loves. I never bought them before, but once I started making them I've certainly become hooked!
What are they? Bath bombs are a very simple chemical reaction. At their heart, they are made from very tightly packed baking soda (a base) and citric acid (a weak acid). Those two ingredients are perfectly fine living together while dry, but adding water produces a rather impressive reaction of fizzing and bubbling.
How are they made? First, bath bomb ingredients can vary so much that listing all possible ingredients is beyond the scope of this post. A basic bath recipe might look like this:
1/2 cup baking soda; 1/4 cup citric acid; 1 tsp oil of choice; 2 ml fragrance oil
The typical ratio of baking soda to citric acid is 2:1, but this can vary up to 3:1. The purpose of the oil is to help the mixture stick together and to provide benefits to your skin while in the bath. The amount and type of oils used can vary wildly. Additional ingredients can include cornstarch, bubbling agents, clay, dried flowers, colorants, etc. Exact recipes are usually a closely guarded secret among small businesses, but there are tons of recipes out on the interwebs if you want to see some variations!
Why do some float and some sink? There are at least three ways to get a bath bomb to float:
- Make it small, light, and/or loosely packed
- Use a lot of additives like cornstarch
- Use a clever mold that allows the bomb to behave like a little boat
I'm sure there are more ways, but to be completely honest, it is not something I am passionate about. I like a pretty bath as much as the next person, but my preferences lie towards dense, heavy bath bombs that are loaded with skin-nourishing ingredients (and a lot of fragrance!) and not much more. (read: get off my lawn!)
Will the tub require cleaning afterwards? It depends on your bath bomb. If you look at the recipe above, that will not leave any lasting evidence on your tub. As a recipe scales up with more oils (and butters), eventually it can leave an oil ring around the tub after the bath. Additionally, the tub can become more slippery, so please use caution when standing! In my experience, the oil content should hover somewhere between 6-12%, depending on the oils. Yes, I know that's helpful!
Large amounts of additives such as clays, cornstarch, etc. can leave sediment/residue on the bottom of the tub. Dried flowers or buds will probably stick to the sides and bottom of the tub, but of course a simple wipe-down of the tub can remove this. (I detest cleaning the bathroom, so my personal nightmare bath bomb involves a ton of shea butter, colorant, and tiny plant parts! Additionally, my house was built in 1889 and has the bad drains to prove it.) Remember, I am only expressing my personal preference! The only person who can truly judge the bath bomb is the user.
What do you use in your bath bombs? I must have tried over 50 recipes and then endlessly tweaked them over the years. I am one of those delightful individuals who is never satisfied and always needs to know if another recipe is BETTER. My recipe generally includes a large proportion of baking soda & citric acid for maximum fizzing and bubbling. I use a bit of kaolin clay both for its skin properties as well as the structural integrity it lends to the bath bomb. Occasionally I use a bit of SLSA, which is a naturally derived bubbling agent. I love colorant, but again, I don't want to be scrubbing my tub afterwards! My favorite oils to use include macadamia oil and cocoa butter. Macadamia oil is just all-around awesome for your skin, and cocoa butter is one of only three FDA-approved occulsives. An occlusive forms a protective barrier on your skin, helping to prevent moisture loss. Soaking in a nourishing tub and then coming out with a protective layer of cocoa butter is just full of win, in my opinion! (As an added note, I occasionally switch my recipe according to the season. The product page will always display the actual ingredients used.)
In summary, bath bombs come in all shapes and sizes and with all manners of ingredients. The only way to find out what you like is to try them all! My nightmare bath bomb that I described above may be your holy grail! You might like more or less fragrance, more or less colorant, etc. than I use. In any event, if you've never tried a bath bomb... treat yourself!