I love bath bombs! I used to spend a bunch of money on fancy ones from Lush (which are super amazing) but soon realised that the ingredients are things that I have at home. After a bit of research and trial and error, here is my method for making lovely fizzy smelly bath bombs - easily!
First, here's what you'll need.
Bi-carb soda (sodium bicarbonate)
Scented oil - essential oil, massage oil, food flavouring oil. I found some vanilla-scented massage oil. Make sure it can be used on the skin. If you don't want a scent use olive oil.
Mixing bowl and mixing device (like a spoon or whisk)
Epsom salts are supposed to be good for your muscles when you soak in a bath. I don't know why.
You need two parts bi-carb soda, and one part of each epsom salts and citric acid. Since the citric acid comes in a little container I use that to measure out the rest.
First, add the epsom salts to a bowl and add your food dye. Make sure you do this FIRST, since if you add food dye to the whole dry mixture it'll fizz.
Colours I recommend: Pink, Blue, Purple, Green.
Colours I don't recommend: Yellow, red. Just because it'll seem like you weed or bled in the bath.
Now add the citric acid and bi-carb and mix around!
Now you have a dry mixture that's pretty and colourful. Now you can add your oil. The oil is not only the scent but also is the sticking agent, so add enough that you can make a shape with the mixture when you squeeze it - but not too much. Because it's oil and not water, it won't fizz!
Lay out your glad wrap and put your cookie cutters on top. Start spooning the mixture in and squish them down as hard as you can. The more you squish the mixture the longer it'll fizz in the bath!
Leave them in their moulds for a while and then gently push them out. Leave them to dry for a day or so. Make sure you don't pile them together or you'll end up with one giant massive bath bomb! They will FUSE.
Enjoy your fizzy pretty aromatic bath!