Plastic moulds can be a bit hit & miss. You can get great results, but often too much pressure can make them crack and prolonged use can cause the surface to deteriorate. The flip side to this is that they are cheap and come in a wonderful variety of shapes.
Don’t apply too much pressure
Bath bomb mixture needs to be compressed when you are moulding. This is how it retains its shape when it is removed from the mould. This is really easy to do with metal moulds, but less so with rigid plastic. To get the best results, fill each half loosely with mixture and pile a little on top. Bring the two halves together and press, just enough to bring the mould together.
Use a spoon to tap on the mould – this will help break the vacuum/seal. Listen for a hollow sound, this will tell you the bath bomb has come away from the mould.
Bath bomb mix sticking to the mould?
Fragrance and essential oils can lead to degradation of the plastic over time. We tend to use these moulds about ten times before recycling them. You will know when they have reached the end of their life, because your bath bomb mixture will start to stick. You can get round this in the short term by sprinkling a little bicarbonate of soda in the mould before filling, but recycle soon after.
Great shaped bath bomb moulds!
Because the hard plastic moulds are so cheap, there is a great variety of shapes available. Whilst you can buy multipacks of individual shapes, buy a multipack to get variety. Doing this will give you an assortment of shapes from the same batch of mixture. Some of the moulds we’ve used are listed below.
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