How To Make Beautiful Bath Bombs
Becoming a Bath Bomber: What Are Bath Bombs, Anyway? And What's the Point?
Recently, one of my farmers' market customers asked me jokingly, "So you're a soaper?" (You can be forgiven if you don't get the joke here--and I'm not sure I did either--but I think she was kind of amused by the idiom.)
I replied, "Yes! And I'm also a bath bomber!"
A bath bomb is basically a giant Alka-Seltzer for your tub. But in addition to fizzing explosively, it also scents and colors the bath water and may contain other ingredients, such as emollient oils or butters, botanicals, glitters, purifying clays, exotic salts, or Epsom Salts for soothing away aches and pains and tired muscles.
Bath bombs are the perfect scented complement to an indulgent "girl night" of mud masks, facial treatments, hair treatments, manicures, pedicures, and a long soak in a scented candle-lit bath--maybe with a glass or three of wine.
I used ornate ball-shaped silicone molds--instead of the plain globular bath-bomb molds used by most people--for the bath bombs pictured. They are easy to use and make especially beautiful creations..
When using silicone molds like these, with small openings relative to the diameter of the finished bath bomb, it's a good idea to make about four slits in the opening to make the bath bombs easier to remove from the molds.
Choosing Bath Bomb Colorants
Probably the most important thing to know about making bath bombs is which colorants are FDA approved for this purpose. Since bath water comes in contact with mucus surfaces, colorants used in bath bombs must be approved for use in products that contact mucus surfaces. Colorants that are considered lip-safe can be used to color bath bombs.
Micas are approved for use in bath bombs, provided they do not contain chromium oxide green or ultramarine blue. A straight color additive, such as a dye or Aluminum Lake are allowed but must be Batch Certified. https://www.madmicas.com/blogs/news/fda-regulations-what-colors-are-allowed-in-bath-bombs
Luckily, there is an easy way to be sure you are selecting FDA-approved colorants for your bath bombs. Most suppliers now offer a selection of colorants that are specifically for use in bath bombs.
Polysorbate 80 in Bath Bombs
One thing that bath bombs should include, if you are using oil-soluble micas or oils/butters, is polysorbate 80. Polysorbate 80 is an emulsifier. It's purpose to dissolve oils in water and it is used in many oil-and-water mixtures, including foods. Bath bombs made without polysorbate 80 will not dissolve in the bath water but will instead created a colored scum on the surface of the water and leave a mess in the tub and on the skin.
Some bath-bomb makers do not include Polysorbate 80 in their creations. Maybe you can get by without it, if your bath bomb recipe includes little or nothing in the way of oils or colorants.
My Simple Bath Bomb Recipe
For my bath bomb recipe, I have kept it simple. I use color, fragrance, and a little argan oil for making skin feel moisturized.
This recipe makes rock-hard bath bombs that unmold easily.
For this recipe, I've chosen a rose-scented fragrance oil and a pink mica colorant, but the choice of color and fragrance is yours.
I have specified using a DEEP mixing bowl, because mixing the powdered ingredients with an electric mixer tends to make the powders fly all over the place and a deep mixing bowl (partially) solves this problem.
- 2 cups Baking Soda, sifted
- 1 cup Citric Acid, sifted
- 14 grams Argan Oil
- 9 grams Polysorbate 80
- 14 grams Essential Oil or Fragrance Oil
- 1 tsp. Pink Mica
- 91% Isopropyl Alcohol, in a spray bottle
Deep mixing bowl
Electric hand mixer
Spoons for mixing
Step 1: Measure Baking Soda into a Strainer Over Your Bowl
Baking soda can be lumpy, so you will need to place a strainer over your mixing bowl and measure two cups of baking soda into the strainer and sift it into the bowl.
If you don't run the baking soda through a strainer, your finished bath bombs will have white spots.
Step 2: Adding the Mica Colorant
Measure one teaspoon of mica colorant into the bowl of baking soda. If you would like a stronger color, you can add more.
The color of the mixture will darken a little after the liquid ingredients are added.
Step 3: Mix the Mica Colorant with the Baking Soda
Use an electric mixer to mix the mica colorant with the baking soda. Be sure to mix thoroughly. It's a good idea to use a rubber scraper to do some of the mixing and to be sure there is no uncolored baking soda at the bottom of the bowl.
Stir now and then to check for spots and streaks and mix until the color is evenly blended.
Step 4: Weigh the Liquid Ingredients and Add to the Baking Soda Mixture
Weigh the fragrance, argan oil, and polysorbate 80 into a small bowl and stir them together.
Add these liquid ingredients to the baking soda mixture and mix well with your electric mixer until everything is well blended.
Step 5: Straining the Citric Acid into the Mixture
The citric acid, like the baking soda, needs to be run through a strainer to prevent white spots in the finished bath bombs from uneven coloring.
Thoroughly mix in the citric acid.
Once the citric acid has been added, you now have a mixture of an acid and a base, and these will react with each other when they come in contact with water.
While this does not mean that you need to work quickly after adding the citric acid, it does mean that this is not a good stopping point for a lengthy interruption that would allow the mixture to absorb water from the air.
Step 6: Spraying the Mixture with 91% Isopropyl Alcohol
The bath bomb mixture needs to be moistened to about the texture of wet sand.
You will know when enough moisture has been added when you can pick up a handful of the mixture and squeeze it together, and it retains its shape without cracking or shattering when you drop it back into the bowl.
Use a spray bottle filled with 91% isopropyl alcohol (IPA) to spray the mixture, stirring as you go.
I am told that the amount of IPA you need is highly variable, depending on the humidity of the air. For example, your box of baking soda may have absorbed moisture during storage. (Lumps in the baking soda are a sign of this.) Or maybe it didn't. Citric acid should always be stored in an airtight container, because contact with moisture in the air will cause it to deteriorate and lose its acidity--at which point it won't work for making bath bombs.
For me, it usually takes 48 squirts with a spray bottle to effectively moisten the mixture--and sometimes more, if I'm using a very dry, freshly opened box of baking soda. The number of times you will need to spray the mixture will also depend on your spray bottle, and how much one squirt will deliver. It's a good idea to keep count of how many squirts you used, so you will have a future guideline.
If the mixture is too dry, your finished bath bombs will crumble. If the mixture is too wet, your bath bombs will swell up in the molds and crack.
So the idea is to give the mixture a few sprays of IPA and check to see if a handful of the squeezed mixture will hold it's shape when dropped into the bowl. The idea is to spray the mixture with IPA until it has just reached to point where it will hold together when dropped--and no more.
The mixture should feel like wet (or wet-ish) sand at this point.
You shouldn't be discouraged if you don't get it just right the first time. (Few people do.) Bath bombs that crumble, or swell and crack, can be crushed up and used as a fizzing bath powder, so they'll still be fun to use.
Be sure to mix the IPA thoroughly into the mixture using an electric mixer. It is important that the mixture be evenly moisturized.
Step 7:Filling the Molds
Now you are ready to press the mixture into the molds.
With silicone molds, it seems to be best to stuff the molds quite tightly, pressing the mixture against the bottom, sides, and top edge, and then adding more to the center till the mold is full. Then add a bit more mixture to the top.
Step 8: Pressing the Mixture into the Mold
Since we want a nice, smooth surface for the bottom of our bath bombs, we need to use something smooth to press the mixture into the mold. I've used a glass bottle that happens to be a near-perfect fit for the mold's opening. A jar lid with a flat top would probably also work well.
Step 9: Now We Wait
Once you've filled all your molds and used up all the mixture, set the molds aside, uncovered, for at least six hours. Overnight is probably better.
Step 10: Unmold and Shrink Wrap
After the molds have rested, uncovered, for at least six hours (though 8-12 hours is safer), you can unmold the finished bath bombs.
Bath bombs unmold easily from silicone molds.
When using silicone molds with a small opening, I make slits in the opening before I use them. In the case of these molds, I made four slits. This allows you to remove the bath bomb from the mold without damaging it.
After you remove the bath bombs from the molds, dust off any crumbs from the bottom. If there are crumbs stuck in the intricate design, you can brush them with a small, stiff makeup brush.
Bath bombs should be shrink-wrapped, or wrapped in plastic, very soon after unmolding so that they don't absorb moisture from the air and deteriorate. But let them sit for about an hour before shrink wrapping to let the alcohol smell dissipate.
Using Brambleberry's LaBomb Bath Bomb Colorants
You can use the above recipe to make bath bombs using Brambleberry's LaBomb colorants. Just substitute 10-30 drops of one of these liquid colorants for the mica colorant in the recipe and proceed in the exact same way--well ALMOST the exact same way.
One of the chief complaints about Brambleberry's LaBomb colorants is that they are hard to mix. The first time I used one of these colorants, I cussed all through the mixing process--swearing to myself that I would never buy this stuff again. I mixed and mixed, and even ran the baking soda and colorant mixture through a flour sifter about a dozen times, trying to get the spots out.
After I unmolded the bath bombs and saw the color, I was converted! I was willing to use these colorants, no matter how much extra work was involved.
But there is an easy way to do this.
Measure out about 1/4-1/2 cup of baking soda in a small bowl and add 10-30 drops of the LaBomb colorant to this and mix until the color is evenly distributed and there are no spots or streaks. Then add this mixture to the rest of the two cups of baking soda and proceed as per the above directions.
This method is much faster and works really well.
The bath bombs pictured are made using the Teal LaBomb colorant. The first (darker) one was made using 30 drops. The lighter one was made using 10 drops.