Some insights into making Bath Bombs

Though they come in a rainbow of colors, shapes, and sizes, all bath bombs share the same base elements.  A combination of acids and bases provide the fizzing action, while powdered ingredients, such as milk powder, salt, or starch, provide filler.  Finally, a binding agent works to keep everything packed tightly together.  Aromatics, colorants, and other additives are often included as well, but really, you could create a basic bomb from just three ingredients: Baking Soda, Citric Acid, and water.  

While plenty fizzy, such a simple bath bomb would be a little lack luster, especially compared to the amazingly creative bombs being made by artisans and crafters nowadays.  By tweaking each component of a bath bomb, you can create truly unique recipes.  We'll go into detail on each element to show you how.

Acid & Base Combo

Theoretically, you could use any skin safe acid and base combination to create the fizzy bubbles that bath bombs are known for, but the classic pairing of Baking Soda and Citric Acid is tried and true.  Start with a ratio of two parts Baking Soda to one part Citric Acid, and you are guaranteed to pack your bomb with fizzy action.  The acid and base combo should make up between 60% and 90% of your total bath bomb recipe.

Powdered Ingredients

While not strictly necessary, powdered ingredients help to improve the benefits and texture of bath bombs. so I highly recommend including them in your recipe.  Almost any skin safe powder can be used to amp up a bath bomb, but the most commonly used are Milk Powders, Salts, Starches, Clays, Honey Powder, Grain Powders, and Herb Powders.  Choose your ingredients according to your imagination.  Powdered ingredients can fill up to 40% of your total bath bomb recipe.

Colorants

Bath bombs are quite versatile when it comes to color.  You can use both water based and oil dispersible colorants, but they must be used in different ways.  Water Based Dyes, which are usually liquid, can be added to water based binding agents, or they can be added to the powdered ingredients using salt.  Dye the binding agents or salts before adding them to the recipe.  Liquid or powdered, oil dispersible colorants, such as Oxides, Micas, or Oil Dispersible  Dyes can be added to oil based binding agents, or they can be mixed in with almost any powdered ingredients.  The amount of colorant that you add to the recipe can be adjusted to yield different shades of color.  Just remember that using too much colorant could dye skin and bath fixtures.  When in doubt, use less.

Something to keep in mind when choosing your colorants is the nature of each type of colorant.  D&C  Dyes (Colors especially for the Drugs & Cosmetics industry)
provide bright, bold color, but they can fade and bleed over time.  Micas and Oxides are less likely to bleed.

You can also incorporate color into your bath bombs by working with naturally colored powdered ingredients.  Many Clays and Herbs yield beautiful colors when included in bath bomb recipes. 

Aromatics

Scenting bath bombs is equally versatile.  The ingredients most commonly used to scent bath bombs are Fragrance Oils and Essential Oils, but bath bombs can also be scented with Absolutes, Attars, or CO2 Extracts.  Light scents can even be added by using an aromatic binding agent such as Hydrosol or Floral Water.  Finally, aromatic oils and butters can also help lend natural scents.  Ingredients like Cocoa Butter or Organic Virgin Coconut Cream Oil can add a subtle touch of scent to bath bombs.  

When scenting your bath bombs, keep skin safety in mind.  You should never use more Essential Oil or Fragrance Oil than is safe for one bath.  Try to keep your aromatics at a ratio of 1 - 5% of your total recipe.

Additives

Visual elements,  such as flower petals, sugar decorations,  or whole herbs should be included with the powdered ingredients when calculating your formula.  These ingredients can be added in with the other powders, or they can be embedded during shaping or molding.

Binding Agents

Pulling this all together are your binding agents.  There are two types of binding agents commonly used in bath bombs, oil and water. Whichever agent is used, it should make up between 10% and 20% of your total recipe.

Oil Based Binding Agents

Hard Butters and Oils, such as Cocoa Butter, Shea Butter, or Coconut Oil, can be used to bind bath bomb ingredients without setting off their chemical reaction.  They also add moisturising benefits to the bombs.  Because these kinds of bombs will only harden when the oils cool and set, they are best molded individually.  With a little practice, these types of bath bombs can be shaped with ballers or scoops, but it can be a little tricky.  When using these binding agents, your bombs are likely to be softer and more fragile than when using water based binding agents.

Water Based Binding Agents

Because water sets off the chemical reaction within bath bombs, it makes using a water based wetting agent more than a little tricky.  However, when done right, it results in rock hard bath bombs that are virtually indestructable.  The hardness can vary depending on technique, ingredients, and mold shapes.

As mentioned earlier, any water based ingredient can be used as this type of binding agent.  Hydrosol, Floral Water, or plain water are the best to use.  It can also be helpful to add a little alcohol to the agent to ensure that it dries quickly.  

Assembly

Start off by preparing all of your components individually.  Combine your powdered ingredients, and create your binding agent.  Next, slowly add the binding agent to the powders, continually stirring to keep the ingredients moving.  If you are using an oil based binding agent, simply drizzle the liquid in a little at a time.  For a water based binding agent, using a spray bottle works best.  Wet the mixture a little at a time until it reaches the consistency of snow.  The mixture should pack and bind in your hands, but it should not be too wet.  When you've reached the right consistency, pack the mixture into molds, or shape it with scoops or ballers, remove immediately from the mold then allow the bombs to air dry for 3 to 6 hours, and then they should be packaged in air tight containers or wrapped.

Basic Recipe

Use this basic formula to create your own unique bath bomb recipes!

• 1 part Citric Acid
• 2 parts Baking Soda
• 1 part Powdered Ingredients
• 10 - 20% Binding Agent
• 5% Aromatics
• Color as desired