Measure out the bicarbonate of soda and the citric acid into the mixing bowl, seiving if necessary and thoroughly mix together until you have a consistent texture.
If using liquid food or cosmetic/soap colours, add, in drops, enough colour to make the shade you want, mixing it in quickly to avoid it fizzing up.
If using a powdered colour, simply add, a little at a time, until you have your desired shade.
Measure 10ml of either fragrance or essential oil into mixture. Most essential or fragrance oils will not cause the mixture to fizz, but certain citrus oils may, so if this happens, mix in quickly and thoroughly.
Do not leave the mixture to stand or it will slowly start to set.
Now, a little at a time and working the mixture all the time, spray a little water on it with the hand sprayer. Mix continuously to avoid it fizzing-up in the bowl and ONLY ADD ENOUGH WATER TO HAVE THE MIXTURE START TO HOLD TOGETHER WHEN LIGHTLY SQUEEZED IN YOUR HAND.
Once this point is reached you need to work quickly to compress the mixture into your moulds.
Using our cup cake 4-on-1 mould, this mixture will make approximately 8 cup cake bases. Press the mixture into each mould firmly and leave a raised (slightly domed) top surface.
After 30-40 minutes they should be quite hard. Simply take the bath bomb from the mould and leave it to dry.
Take your cup cake paper cases and put one in each of the now empty moulds, then drop a bath bomb into each paper case, allowing the top of each case to come above the top of each bath bomb.
Next, gently melt your 200g of white soap base in the saucepan over a low-medium heat. Once melted completely, remove from the heat and add any liquid colour you may want to, then, using the electric whisk, whisk briskly until it becomes a light, airy consistency. This is generally achieved by whisking past the stage where it forms large bubbles and as the soap cools slightly it will become a smooth, near-mouse-like consistency. Once there, quickly, before it sets up, spoon your mixture like icing onto each cup cake base, making sure it completely covers the top of each bath bomb and is contained by the paper case. Allow to cool and set.
As an alternative to using regular melt and pour soap as an icing, a soft icing can be created using either what is commonly known as Ice Cream Soap (we stock Crystal OPC, sold as Foaming Bath Butter) which can be whipped in the same way as above or by using a Cream Soap. Either can be used successfully and by using a soft substance to ice your cup cake you can also pipe it into creative shaped iced toppings.. If using a soft icing, a paper case may not be necessary and care should be taken with any packaging or shipping.
A few coloured sugar strands, or alternatively coloured SLS noodles make a simple and easy addition to the topping, as does cosmetic glitter or flower petals and other decorative botanicals.