How to make your bath bombs super smooth


One thing a lot of people who make their own bath bombs struggle with is, is getting a shop bought smooth finish. However, there is a really easy way to do this – the professionals know the answer, and its not a secret!

It’s all about the citric acid!

Citric acid is the ingredient which reacts with bicarbonate of soda, to give a fizzing reaction when the bath bomb hits the water. 

It occurs naturally in citrus fruits, but is also manufactured. It is commonly used as an acidic regulator in the drinks industry but is also used widely in the food and cosmetics industries.

For bath bombs, use the water free version which is known as Anhydrous. Check the information from your supplier carefully, to make sure it is Anhydrous – sometimes it will not be obvious.

When you should add citric acid to your bath bombs

It might not seem obvious, but there is a perfect time for you to add the citric acid to your bath bombs. Once the bicarbonate of soda and citric are mixed, you need to mould your mixture quite quickly. These two ingredients react and allow the mixture to bind. 

Your other ingredients can all be added to the bicarbonate of soda, with no real impact. So get your colour, fragrance, other dry ingredients and any oils (if you are using them) combined with the bicarbonate before you even think about adding the citric acid.

How the professionals make super smooth bath bombs

The answer to this question is astoundingly simple. It comes down to the grade of citric acid you buy. Most citric acid is sold in granule form. This works just as well in the bath bombs, but you will get a rough finish. You may also see mottling or white parts on the bath bomb. This is because the granular nature of the citric acid cannot absorb the colour. 

If you have bought granular citric acid and want super smooth bath bombs, you can use a coffee grinder to reduce it to powder. This works really well but can be very messy. 

The easiest way to get an instant and amazing smooth finish is to buy citric acid powder. You may need to go to a cosmetic ingredients wholesaler to buy this, but it really is worth it. It makes an amazing difference to the texture and feel of your finished product.

Where to buy the best citric acid

If you want to know more about ingredients, check out our ingredients page