I like to use an electronic scale to measure my ingredients. It’s not absolutely necessary, but sometimes there’s a chance of (benign) chemical reactions if the quantities are wrong, and this is a much more precise way to do it. I’ve included “measuring cup” equivalents below, but if you think you might do this sort of thing more than once, I’d highly recommend getting a scale.
Here we go:
300g Epsom Salts (1 1/3 cups)
200g Baking Soda (3/4 cup)
25g Whole Milk Powder (1/4 cup)
75g Citric Acid (1/3 cup)
3-5g Essential Oil Fragrance (1/2-1 teaspoon)–you want the perfumerie essential oil, not the kitchen “extract”
5g Cornstarch (slightly rounded teaspoon)
Few drops Food Color
Read directions all the way through before starting. It’s easy, but it’s not just “dump it all in a bowl and stir.” Also, Pro Tip: Make sure all your tools and containers are perfectly dry before starting out. Use non-reactive (stainless steel or glass), implements and containers.
- Measure the ingredients (except fragrance and color) into separate containers before you start. This will make the process easier and faster.
- Start with the Epsom salts, baking soda, and whole milk powder. (Any guys who are attempting this–fear not, we know you’re not making them for yourself, they’re for the woman in your life–it’s baking soda you want, not baking powder. I mention this only because making that distinction has been meaningful in the past, in my own life. I say no more.)
- Mix the Epsom salts, baking soda, and milk powder together. If there are any lumps at all, press them out with the bottom of a dry glass, until the ingredients are evenly mixed.
- Take your shot glass (or similar container) of cornstarch and add between 1/2 and 1 teaspoon (3-5 grams) of essential oil. Different oils have different aromatherapy properties, and can be soothing, energizing or relaxing as you wish. I used lemongrass oil here, as it smells fresh and “Springy” and the weather has been dreary and foul for some time, so I could use a boost. Mix up the cornstarch and the oil (the cornstarch acts as a natural fixative, and will make the scent last longer. Also, it makes mixing the oil evenly into the salt/soda/milk mixture easier).
- Now color the mixture with a few drops of food coloring. Don’t go hog-wild. You want the mixture to stay as dry as possible. 4-6 drops should do it. You don’t want bold primary colors in your bath water. At least, I don’t. Maybe you do. No accounting for taste. Anyhoo, place the drops randomly in the mixture. and stir like mad until the color is evenly distributed.
- Stir the color/fragrance mixture into the salt/soda/milk mixture. Mix evenly.
- If there’s a “tricky part,” it comes now: Add a little citric acid to your mixture. It should not fizz. If it does, pour yourself a nice warm bath, and dump the rest of the citric acid into the salts, and tip the whole lot into the tub. Go to town. (Or, put the rest of the citric acid back in the bag, and enjoy your already finished non-fizzing bath salts, which you can put in an airtight jar with a lid. You don’t want things to fizz now. If they do, take a breath and follow one of the above bits of advice).
- If all is well, and no fizz, add the rest of the citric acid and stir well.
- Then put in a nice, airtight glass jar. (The jars that Yankee Candle Company (or similar) puts their candles in are perfect, once the candle is gone, and you’ve washed the jar with boiling water and got all the wax out of it. Don’t put the waxy water down the kitchen sink drain.)
The salts should last a few weeks. They will soak up moisture in the air if given the chance (which is why you want that airtight lid), and if that happens, they’ll fizz and get soggy. If that does happen, they’ll still smell nice in the bathwater, but they won’t fizz.
If all is well though, about 1/2 cup in the tub should have a very satisfying fizzy effect, and should smell lovely. Happy Soaking!
PS: Variations–you can eliminate the color and/or fragrance. Neither is essential (pun), although the fragrance is nice and does have a bit of a psychological effect. If you’re not wild about the fizz (which is really just a bit of fun), you can leave out the citric acid and just make fragrant bath salts. You can also eliminate the whole milk powder. I use it because it has some fat in it, and milk has been used as a traditional skin softener for thousands of years. I believe (possibly delusionally) that it make a difference.