Our Guide to making great bath bombs
Basic bath bombs are really simple to make and a great craft project to tackle with children. That said, there are a few things that can go wrong along the way along with many, many ways to give your bath bombs that special wow factor.
The Basic Mix: In its simplest form, a bath bomb is made with 2 parts sodium bicarbonate (baking soda) and 1 part citric acid, plus a spray of water to dampen it and enable moulding. Use a whisk or sieve to get all the lumps out of your dry mix for an even surface on your finished product. TIP! For even fizzier bath bombs, increase the citric acid by 50% (be warned, its definitely harder to make them like this!).
Not all citric acid is the same! I would recommend using fine citric acid rather than granular. It is a little trickier to work with, but gives a much better end result. Also, be sure to use fresh citric acid – the shelf life may be as long as 3 years, but it will gradually react with the humidity in the air making it less fizzy over time so is best used within 6 months for bath bombs. TIP! Keep your citric acid in an air tight container, and add a silica gel packet if you have one.
Variations on the basic mix: Many recipes add 1 part Epsom salts which are great for easing muscular aches in the bath – be sure to use fine Epsom salts if you do this. Another common addition is 1 part cornflour or kaolin clay. Either of these will help to harden the bath bomb and are particularly useful in humid climates.
Skin loving ingredients Another way to increase the skin benefits of your bath bomb is to add oils or butters. These can be added at 20-30g per 1kg of dry mix (2-3%). TIP! Adding 4-7% polysorbate-80 will ensure that your butters and oils disperse into the bath water and help to prevent glitter or colour residues on your bath-tub.
No citric acid?? I’ve seen a few articles suggesting recipes that do not use citric acid – instead substituting lemon juice, cream of tartar or cornflour. Whilst these can make interesting bath products, I have found that they really have very little fizz at all. For bath bombs it really does need to be citric.
Which Liquid? Using a water mist will absolutely work, but if you are having trouble with the citric acid reacting, then try using witch hazel or isopropyl alcohol (50% with water) instead.
The Fun Stuff – Now you’ve got the basic mix sorted, its time to have some fun, after all it’s the colours and glitters and aromas that really give bath bombs their appeal.
Colourants need to be chosen carefully as they often interact with the alkali environment inside a bath bomb causing them to discolour. The safest choice is to use pigment powders which are easy to mix in without adding extra moisture. How much you use is personal taste, but generally 1-3g of pigment powder will colour 1kg of dry mix.
Again with aromas, care needs to be taken. Some can discolour, others can change their aroma, and still others (particularly citrus oils) may cause the citric acid to react. Generally, you will need around 10ml of fragrance or essential oil for every 500g of dry mix, but again, this is personal taste as well as varying between aromas.
Moulds – You can buy specially made, plastic moulds online in many shapes and sizes (Denny Craft Moulds have a great range at reasonable prices). If you will be reusing your mould many times then you might want to consider investing in silicone or metal moulds which are more durable. There are also many things you will find around your home or in local shops that work just as well – why not try ice cube tray, baking moulds, cake cases or easter egg packaging to name a few. Anything with a cavity can work! TIP! If you are finding it hard to release your bombs from the mould, dust the mould with a little bicarb or corn starch before filling.
Packaging – Bath bombs deteriorate when exposed to moisture in the air, so we recommend using shrink wrap to keep them in great condition for around 6 months. You can buy shrink wrap bags online that work with the heat from a normal hair dryer if you don’t have a heat gun.
Remember, with bath bombs, the only limit is your imagination. There are thousands of ideas on sites like pinterest from the basics through to stripes, swirls, layered and hidden colours, layered fragrance, dried botanicals, glitters & micas and even hidden toys.