Tilly (geeksicle) wrote in hgch_lessons,

Shock scandal! Hogwarts Potions Professor teaches students to make bombs!

With Christmas approaching I thought it would be nice to set aside a lesson to teach you to make something you can give as a gift. Today we will be making bath bombs – a muggle invention that will certainly be appreciated by whomever it is who has to prepare and organise Christmas dinner at your place. I have often given one or two of these in a basket with a book and a bottle of wine and labelled it a “relaxation kit”. Your instructions are on the board. You may begin now.



1 cup baking soda (sodium bicarbonate)
½ cup citric acid
½ cup cornstarch (this is not an active ingredient; it simply gives the bath bombs a smoother, more professional appearance. You may leave it out, but will need to adjust the quantities of liquid added accordingly.)
Optional: 1/3 cup Epsom salts (these soften the water and seem to add fizziness)
Optional: dried flowers or herbs for appearance


2 ½ tablespoons of sweet almond oil (you can substitute sunflower or other light oil if necessary – be aware that a good quality olive oil, while good for the skin, will make the bath bomb smell faintly of olives)
¾ tablespoon water (depending on the fragrance you wish to add you may use rosewater, orange flower water or similar)
1 teaspoon essential or fragrance oil of your choice
¼ teaspoon borax
Optional: colorant (food colouring works, but be sure to use very small amounts or you may end up with stained bathtubs)


Plastic moulds such as large hearts or Christmas ornament moulds
Measuring spoons
Glass jar with lid
Measuring cups
Large bowl
A cookie sheet lined with waxed paper, wax-side up
Plastic or rubber gloves (recommended but not essential)


Sieve the baking soda, citric acid and cornstarch into your bowl until well blended. Add the Epsom salts along with your herbs or flowers (tiny rosebuds look quite lovely) and mix with your hands until thoroughly combined. Set this aside, measure and combine all your wet ingredients in a small, clean glass jar. Cover tightly and shake to combine well. Slowly trickle the wet ingredients into the dry, stirring all the time with your gloved hand. If you hurry this stage – Weasley, I’m looking at you – and dump in the liquid, the water will react with the dry ingredients and you’ll have a useless, foamy mess. Keep blending until the mixture just holds together when you squeeze it firmly in your hand. If it is too dry and will not reach this stage, you may need to add a little more almond oil. Make sure it is thoroughly mixed and try to work quickly, before it starts to dry.

Pack your mould quickly and very firmly, so they look as if the mixture wouldn’t fall out if you were to suddenly tip it upside-down. If you are using the Christmas ornament mould or other double-sided moulds, throw a little loose mixture over one half before firmly squishing the halves together. Press as hard as you can, but don’t twist them. The sides of the mould may not meet – this is fine, and actually makes it easier to extract the bomb. If you are not confident you may wish to enlist the help of an assistant to help you pack the moulds before the mixture becomes too dry, but this is a fairly small batch and should not be too difficult.

Let the bath bombs rest for around five minutes, tap them gently against your work surface and unmould them onto a baking sheet. If you are using double-sided moulds ease one side off at a time, and do not twist the halves or your bomb may crumble or split. If it crumbles, empty out the mould and start again, adding a touch more oil if you just cannot get them to hold shape, and if you are giving them to a nana who will simply be ecstatic that you made her gift, you can probably get away with squeezing it into a ball by hand – just make sure it’s very tightly packed or it will disintegrate on drying. The moulding process is simply for looks – if you have leftover mixture, gather it and throw it into your own bath to enjoy the same fizzy effects.

The bombs should be ready to use after a few days of drying, but I let mine rest for a week to be safe. In humid weather the moisture in the air can react with the bombs – if it is very humid where you are preparing these, you can put them in an oven set no higher than 80 degrees Celsius (roughly 170 degrees Fahrenheit) for two to three hours – a fan bake function would be useful here.

Once the bombs are dry, you’re done.


Design a bath bomb to have a particular effect on the user – for example, a refreshing or energising bomb, or one to use before bed to aid sleep. Tell me the desired effect of your bath bomb and the herbs, flowers, and oils you would use, and please cite your sources.

Remember, no points without name and house. This homework is due by December 15.
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