Common problems with bath bombs

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Is this happing to your bath bomb?

Does your batch bomb fall part before it hits the water? Does it just sink to the bottom of the bath and not fizz like it should? You may be falling for these common mistakes when making bath bombs. Read on to learn more.

So you’ve made your bath bomb, pressed it into the moulds and now for the big moment – pushing out to see the finished product in all its glory. But there’s a problem. It starts to break apart.

What has caused this? Why has this happened? Let’s take a look at common reasons for bath bombs to fall apart and other issues.

Why bath bombs crumble & break apart?

Bath bombs crumble or fall apart if too little force or too much force is applied during the moulding process. They will also crumble if they are too wet when removed from the mould. Moreover, if the bath bomb mixture is too dry when formulated it may disintegrate on release from the mould. Improperly mixed formulations can also lead to disintegration.

Want to learn how to make bath bombs? Read our step by step guide


  1. Use the right amount of pressure during the moulding process – you’ll get experience of what is the right level of force over time.
  2. Allow bath bombs to properly set and dry in the mould
  3. Add the correct ratio of oil/water to your formulation (see recommended formulation below)
  4. Make sure powder and oils are mixed thoroughly ensuring there are no lumps

Why do bath bombs sink to the bottom of the bath tank?

This kind of problem occurs when the bulk density of the ingredients used in making bath bombs is more than the density of water. To avoid this, try to use ingredients with a bulk density less than water. Cornstarch, for example, is better than cream of tartar. Cream of tartar makes the bath bombs sink while cornstarch helps bath bombs to float mainly because of their weights. Another cause of a sinking bath bomb is when it is too tightly packed.


  1. Include Epsom salt and cornstarch in the formulation to help bath bombs to float.
  2. Kosher Salt is another excellent ingredient to make bubble floats in water.
  3. The denser the bath bomb materials are packed together, the more air pockets are locked in improving the floating properties.


You can avoid the problems above and enjoy perfect bath bombs by using the bath bomb recipe below:

No.Ingredients% w/w
1Baking Soda50
2Citric Acid24
4Epsom salt3
5Carrier oil of choice4
6Essential oil of choice1