As I’ve noted before, Instructables has changed their business model, reducing access to content to non-paid visitors. Since all of my work was published under a Creative Commons non-commercial license, I’ve removed it from Instructables and am republishing it here, so the content stays free. Keeping in mind folks with data stream limits, I’ve used smaller images, but you can click through them to larger versions if you wish, or you may see the entire project folder here for super large images.
How to make bath bombs:
Everybody loves bath bombs. It is like taking a bath in champagne, only without the show tunes and chorus boys. They are fairly simple to make, keeping in mind that the strangest things can make a batch go weird; humidity, room temperature, oil viscosity, the moon rising in the seventh house of Aquarius . . . they are a mysterious wonder.
For this recipe, I am using ingredients that are pretty common, or easy to find in most areas. Essential oils can be found in small amounts at places like health food stores and craft stores often carry essentials and fragrances. Just make sure, if you buy fragrance oil, that you are buying “body safe” oils and not stuff for candles or oil warmers. Citric Acid can be found at health food stores, brewer’s stores, and online at various retailers.
So, let’s start with a basic recipe in two parts.
Dry ingredients: (By Weight, as measured on a scale.)
- Baking Soda – 8 ounces
- Citric Acid – 4 ounces
- Corn Starch – 4 ounces
- Salts – 4 ounces ( in these pictures, I used Dead Sea Salts, but mineral salts work too, and are easier to find and significantly less expensive.)
Wet Ingredients:
- Water – .75 tbsp
- Essential or Fragrance Oil – 2 tsp (for these I used a Ginger Peach.)
- Oil – 2.5 tbsp (I used cherry kernel, but any light vegetable oil will work.)
- Food coloring – 1 or 2 drops. (Your color will look very dark in the emulsion, but will be light in the fizzies, so as to not leave rings around the tub. For this batch I used one drop red and two drops yellow. The final result will be very light peach.)
step 1 – Blend the Dry Ingredients
Begin by putting all of your dry ingredients into a big bowl. Glass is best because it is non-reactive. Whisk or pestle those pesky clumps out. You want a fairly smooth consistency throughout the entire mix.
step 2 – Mix liquid and blend dry and liquids together
Blend your wet ingredients together. I usually use a small jar and shake it up. Don’t worry about separation too much, you are not going to get a full emulsion. Then, while whisking, slowly add small amounts of the liquid to your dry ingredients. Here we see my faithful Igor prepare to pour.
step 3 – Try to avoid creating volcanoes
If the mixture starts to foam, you are adding the liquid too fast. Quickly whisk the reacting ingredients into the nonreactive part and you should be able to stop the reaction. I add about a teaspoon at a time. When all of the wet ingredients have been added, you should have a mixture with the consistency of slightly damp sand. It should clump together when you squish it.
step 4 – Mold quickly
Once your mixture is together, you have a pretty limited amount of time in which to get it into molds. To create the giant Soapy Hollow ball of bath doom, I use round christmas tree ornaments that were designed to be filled with goodies. To do a three-dimensional bomb like these, you pack each side, then overfill a tad at the center and press the two sides together.
It takes a little practice to get a feel for how much filling you need, so don’t get discouraged if your first couple fall apart. Here we see Igor holding a filled ball and wondering about child labor laws.
step 5 – Unmold and let dry
You don’t need to leave them in the mold for very long, and in fact can tap them out as soon as you fill them. These are four bombs we made with this batch.
You can use all sorts of things to make your bombs; muffin tins, ice cube trays, candy molds, Aunt Magnolia’s denture case . . . whatever makes you happy.
This batch didn’t make quite enough for five bombs, and the humidity levels made the batch start to puff up, so I quickly stuffed what was left of the batch into my “bath cookies” mold. Note: When using things like silicon trays that surround the seltzer mix, or any mold with a lot of details, the mix must stay in the mold until dry, or it will crumble when you try to take it out.
Once they are completely dry, store bath bombs in an airtight container or bag. High humidity will make them activate. Because we used oil and water and no preservatives, you want to use them within about 6 months. Assuming you can keep them for that long. Igor demands payment in immediate fizzy baths, but you may have better luck actually getting to *use* yours.
When you’re ready to use one, just drop it into a warm bath, and relax.
no matter what I do my halves will not stick together.
Hi Gigi,
Have you tried overfilling both sides, and then mashing them together? You’ll get some that will fall off as the mold sides come together.
Make sure you don’t twist the molds when you’re putting them together, or pulling them apart.
If neither of those works, then use a little less stuff inside the mold, close the molds completely, and let the mix dry in the molds. That’s sort of a last-ditch solution though, cause you need a 5 molds for this batch.
Also remember that the recipe can be impacted by your climate…so if you’re somewhere really dry, you might want to use a spritzer bottle with a little witchhazel, spritz the middle part right before you put em together and see if that helps.
If none of that works, lemme know and we’ll try to troubleshoot it.
Its still on instructables though?
Graham…so it would appear. Hmm.
Hi, your site is great; I really want to try the bath bomb recipe (they are expensive to buy, so making my own sounds like a fun, cost saving approach
). I was wondering if there is a recommendation for finding the molds inexpensively ~ it seems as though the places I’ve checked so far (online) seem to have steeply priced molds. Also, I was wondering if there is a difference in the essential oils at different stores ~ I saw some at the drug store, others at craft stores, and I believe even Bath and Body Works. I am a complete newbie at all of this, so I wasn’t sure if there was a marked difference in them or if the brands are just higher quality than others (my concern is that I’d end up getting something intended for non-skin contact and end up with some funky rash or something).
Hiya Nancy!
I would go with essential oils from a company that caters to the bath&body manufacturing community. For small purchases, I would probably recommend Camden Grey for the best pricing. I’ve also really liked products from Majestic Mountain Sage for high quality, but they are pricey, and I’ve had them flake on a order or two. Also Brambleberry has a good selection and you can buy in small amounts. I love their fragrance oils and highly recommend those, but generally buy EO from Camden if I’m buying in small amounts.
If you start buying in large amounts (more than a pound at a time), I can hook you up with some other really amazing suppliers, but they have large minimum purchases.
For the molds, these guys have the best price I’ve found for the 80mm size.
Hope that helps! Please feel free to ping me with questions! Cheers and happy soaking!
I left my bath boms in the plastic moulds overnight and now can’t get them out!!!!!
Some of them I’ve been able to get 1 half of the mould off but i can’t get the other half off!!!!
Any suggestions or tips on how not to do this again??????
Hiya Kelly,
Yep, I’ve had that happen in a mold before. Grrr, no? I try not to leave bombs in fully enclosed molds, because this can happen, but if you do leave them in a fully enclosed mold, like the christmas balls, before you try to get them out of the mold, tap the mold gently on the counter…about half the force you would use if you were cracking an egg.
You don’t want to whack it, cause you could crack your mold, or break the bomb. Just a gentle sort of tapping all the way around the perimeter opposite of the dividing line. (The two halves meet in the middle, tap in a vertical perimeter.)
That should break any vacuum that has been created inside the mold, and they should release a little easier.
Also, if you think you’ll be leaving them in the mold, it doesn’t hurt to brush a very fine coating of oil on the mold, which makes it easier for them to slide out when you’re ready for them.
Hope that helps! Feel free to ping me if you need any more help!
Thanks a lot for that – will try tonight!!!!!
Hi, could you please tell me if it would be all right to use vanilla extract or rose water instead of the essential oils? I really do not like the smell of the essential oils that they sell at my local health-store and I prefer the smell of vanilla or rose (the rose essential oil they sold smelled horrible in my opinion. Are essential oilds necessary? And do you think the alcohol in the vanilla extract will react with the ingredients?
Yeah, Rose Attar is super rare and unbelievably expensive…(around $3,000 a pound). Most places that sell “rose oil” are selling a synthetic oil. I agree that most of them smell icky.
There are a couple of companies that manufacture an amazing synthetic rose, but they can be really hard to find. IFF makes the best ones on the market, but they only sell in 50 gallon barrels, which…I mean…that’s a lot of fragrance. 
Majestic Mountain Sage and Brambleberry, I believe, sells IFF oils, if you ever decide to try a synthetic.
That said; the vanilla extract may or may not work…I’ve had batches that worked, and batches that just smelled awful after a few weeks. If you want to do a vanilla, the best way I’ve found to do it is to either use a good madagascar vanilla bourbon, or to take some 1/2 cup vodka and scrape the interior of a vanilla bean into it, then soak the interior and the exterior in the vanilla for a few days/weeks. Strain and use.
Assuming the rose water is just rose water without additives like sugars and whatnot, it should work.
Using either of those, note that you may need to add a little bit more of your carrier oil…like any recipe, when you make changes, you may have to tweak it a bit to get it to do exactly what you want.
Have fun, and come back and tell me (show pics!) of how it worked! Feel free to ping me with questions or problems!
receipe worked great:
(sodium bicarbonate) + (citric acid) –> (sodium citrate) + (carbon dioxide) + (water)
does sniffing the exploding fizz cause any inhalation of the produced sodium citrate? i read it is toxic to lungs and mucous membranes.
thanks!
No. Sodium Citrate and Citric Acid are the same thing…and it’s not toxic. According to the FDA, it can be “mildly irritating if the powder is inhaled directly”. The Safety Data Sheet says: Breathing in dust may result in respiratory irritation. May be irritant to mucous membranes of the respiratory tract. It goes on to say:
Acute Oral LD50 (ingestion)
Eye Irritation: Slightly irritating
Skin Irritation: Non-irritant
Mutagenicity: Not mutagenic
Carcinogenicity: Not carcinogenic
Reproduction: Not teratogenic
NOTE: GRAS – (generally recognized as safe for human consumption)
Thus, unless you were pretending to be Keith Richards on a bender in the 70’s, and sniffing lines of it…you’re in no danger.
The equation is: 3NaHCO3 + C6H8O7 –> C6H5Na3O7 + 3CO2 + 3H2O
Citric acid (C6H8O7) and sodium citrate (C6H5Na3O7) are different compounds.
Wikipedia says, “Contact with dry citric acid or with concentrated solutions can result in skin and eye irritation, so protective clothing should be worn when handling these materials.[citation needed]”
~ http://en.wikipedia.org/wiki/Citric_acid
I found my citric acid to have clumps in which I had to pestle out. Didn’t think I needed to be careful with touching it with my bare hands.
?
Well..no. That chemical formula is for Trisodium Citrate. It is sometimes referred to simply as sodium citrate, though sodium citrate can refer to any of the three sodium salts of citric acid.
Citric acid or any of the sodium salts of citric acid can be irritating to the skin in the same way that lemon juice or lime juice can be irritating. I’ve never had any issues, and I’ve done thousands of bath bombs. However, if it concerns you, or if you have any irritation, you can always wear food safe gloves.