Why do the bath bombs crumble?

It was too dry. A little more oil or one or two extra sprays of water, until the mixture holds like damp sand.

Magazine · DIY

Make bath bombs that are guaranteed to fizz

Q: Are homemade bath bombs suitable for children?

In moderation yes, without or with very sparingly dosed essential oils and no strong colour. For sensitive skin keep them plain and rinse the tub afterwards.

Two ingredients make the fizz, the rest is play. The simple base recipe and the trick so nothing sets off early.

The short version

The fizz comes from the reaction between baking soda and citric acid as soon as they hit water. The trick when making them: mix dry, moisten very sparingly, press firmly. Too much moisture and the bomb goes off in the mould.

Bath bombs are the perfect beginner project: no heating, no lye, ready in half an hour and a lovely little gift too. And they use exactly the home-remedy staples you may already have in the cupboard.

The principle is simple, yet one step is easily botched. Let us look at it.

Base recipe · for several bombs

Advertising

DAYTOX Skincare DE

View offer

Fizzing bath bombs

You need

8 tbsp baking soda
4 tbsp citric acid (ratio 2 to 1)
2 tbsp plant oil (e.g. almond or coconut)
optionally some cornstarch for a longer fizz
optionally a few drops of essential oil and a little food colouring
a bath-bomb mould or a small silicone mould

How to

Mix all dry ingredients thoroughly. Add oil and scent, stir. Now spray in water drop by drop with a spray bottle and knead at once, until the mixture holds together like damp sand but does not yet fizz. Press into the mould, firm it briefly, ease it out carefully and let it dry overnight.

The mixture must hold like damp sand, no more and no less.

So they work and do not set off early

Only spray water, never pour. One drop too many and the reaction starts.
Work quickly and press into the mould while the mixture is still shapeable.
Store in a dry place, humidity from the air makes them clump.
Dose essential oils sparingly, especially for sensitive skin and children.
Careful: oil makes the tub slippery, rinse well afterwards.

Recommendation

What makes the start easy

With a few basics the first batch succeeds. What to look for:

Baking soda and citric acid in good, fine quality
A sturdy bath-bomb mould or silicone mould
A spray bottle for precise moistening

View a bath-bomb setAd

Note: affiliate link. If you buy through it we earn a small commission at no extra cost to you. Our recommendations stay independent.

Frequently asked

Why don’t my bath bombs fizz?

Usually the mixture was too wet when shaped, so the reaction had already happened. Next time spray in less water and press faster. The ratio of two parts baking soda to one part citric acid should be right too.

Why do the bombs crumble?

Then it was too dry. A little more oil or one or two extra sprays of water help, until the mixture holds like damp sand.

Are homemade bath bombs suitable for children?

In moderation yes, but then without or with very sparingly dosed essential oils and without strong colour. For sensitive skin keep them very plain and rinse the tub well afterwards.

Magic Soap editors
We write clear, honest guides about soap, care and natural cleaning. Our recommendations are made independently, tested and fairly judged.

Fancy more DIY?

From bath bombs to your own soap, we show you the nicest projects.

Make soap from scratch DIY natural cosmetics

Links marked “Ad” are affiliate links. If you buy through them we earn a small commission at no extra cost to you. Our recommendations are made independently.