Kitchen-Chemistry Bath Bombs
Use real chemistry (an acid plus a base) to make fizzing bath bombs in fun shapes and colors.
- Ages
- 9–12
- Startup budget
- $93–$193
- Time per week
- About 3 hours
- Parent involvement
- High
- Preparation
- Some prep
- Type
- Product
- Where to sell
- In person
- Time to start
- 2 weekends of testing
About this idea
Bath bombs (also called bath fizzies) are a science experiment you can sell. Baking soda and citric acid react in water to make the fizz, and kids can test recipes to make them fizz longer, smell nicer or hold their shape better.
Because they go in the bath, they come with real responsibilities: careful ingredients, clear labels and adult supervision.
A great fit for
- Budding scientists
- Kids who love experimenting with recipes
- Families happy to supervise
What you’ll need
| Item | Estimated cost |
|---|---|
| Baking soda (4 lb bag) | $5 |
| Citric acid (2 lb) | $10 |
| Cornstarch | $3 |
| Silicone molds | $8 |
| Skin-safe soap colorant | $6 |
| Packaging bags and labels | $6 |
| Coconut or sunflower oilOften already in the kitchen | Free |
| Subtotal | $38 |
Assumes: Enough for about 30 bath bombs. Uses everyday kitchen bowls and measuring spoons.
| Item | Estimated cost |
|---|---|
| Market table feePer event. Kids’ markets typically charge $10–50; some are free | $25 |
| TableclothA bright color makes the table stand out | $10 |
| Display stand or risersGives products height so customers notice them | $15 |
| Sign and price cards | $5 |
| Pop-up tentOptionalOnly for outdoor markets without shade. Borrowing one works too | $100 |
| Subtotal (without optional) | $55 |
Bring about $20 in small bills and coins for change. You get it back, so it isn’t counted as a cost. Selling to family and friends first? You can skip these until your first market.
Total to start selling at a market
$93$193 with optional extras
What parents do
Parent involvement: HighSupervising every session or going along on every job
- Buy ingredients, gloves and safety glasses
- Supervise every batch
- Check cosmetic labeling rules before selling
Your child: about 3 hours a week making, selling and planning once it’s up and running.
Step by step
Learn the reaction
Mix a pinch of baking soda and citric acid in water and watch it fizz. That’s an acid-base reaction producing carbon dioxide.
Test a basic recipe
With an adult, mix 2 parts baking soda, 1 part citric acid and 1 part cornstarch, then add a little oil and color.
Experiment and record
Change one thing at a time and write down the results. Which recipe holds together best? Which fizzes longest?
Mold and dry
Press firmly into molds, dry for 24 hours, then pop them out.
Label every product
List every ingredient on the label so customers with sensitive skin or allergies can decide safely.
Costs & pricing example
Cost to make one bath bomb
$0.90
Example price
$5
Profit per bath bomb
$4.10
How we worked out the cost of one bath bomb
- Baking soda$0.15
- Citric acid$0.30
- Cornstarch$0.05
- Colorant$0.05
- Oil$0.10
- Bag and label$0.25
If your child sells 20 baths bomb at $5, that’s $100 in sales and about $82 profit after materials. The $93 startup cost, including a first market table, is earned back after about 23 baths bomb.
Gift sets of 3 in a box can sell for $12–14.
These numbers are illustrative examples, not guaranteed earnings. Prices vary by supplier and location.
Where to sell
Children’s and craft markets
Smell and color attract customers. Bring a sealed sample.
Family and friends
Popular as gifts.
Holiday markets
Seasonal shapes and colors sell well as stocking fillers.
Skills your child will build
- Scientific method
- Measuring and ratios
- Recipe testing
- Product labeling
Common challenges
- Fizzies crumbling
- Try this: The mix is too dry. Add tiny spritzes of water (it will fizz a little) until it holds like damp sand.
- Fizzing too early
- Try this: Too much liquid. Work in a dry room and add moisture slowly.
Safety & parent notes
- Adult supervision
- Handles chemicals
- Check local rules
- Citric acid can irritate eyes and skin. Wear gloves and safety glasses, and have an adult supervise every batch.
- Avoid essential oils unless an adult has researched safe amounts; they can irritate skin.
- In the US, bath bombs count as cosmetics, which have labeling rules (including a full ingredient list). Check the FDA’s cosmetic labeling guidance before selling.
A note for parents
This is the idea most worth supervising closely. Treat it like a science project first and a business second, and keep a lab notebook together.
Helpful guides
Money & pricing
How to Calculate Startup Costs for a Kids’ Business
Turn a supply list into a simple budget your child understands, and find out how many sales it takes to earn the money back.
2 min read
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