Bath Bombs Cracking Days Later

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May 2, 2018
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When it comes to anything crafty or artsy, I have about the same skill level as a 6 year old. Projects that are labeled as "super easy" often leave me stumped. I've been making cold process soap for like 5 years and still can't do even the simplest swirl. I gave up on making "pretty" soap and just make it for functionality now.

I wanted to try making my own bath bombs and found the process to be a lot harder than they make it look in the tutorials. At first, I couldn't get my bath bombs to stick together. Then when I finally did and took them out of the mold they fell a part into a pile of powder.

I really bombed with this project (cue cheesy laugh track).

After about the 1oth try, I finally made bath bombs that stuck together, held their shape, and looked and smelled almost professional. Yay! I let them dry overnight and then put them into a sealed zip lock bag for safe keeping and didn't touch them or move them at all. I looked at them tonight ( a week later) and one of them has developed a huge crack right down the middle, dividing it almost in two. The other one is still looking ok.

What caused the crack and how can I prevent it? Why did one bath bomb crack but the other made from the same batch didn't? I live in the midwest and it is not particularly humid or particularly dry here.

I'm going through a rough patch personally and this small success with the bath bombs made me feel a little better. Now that it cracked I'm way more disappointed than I know I should be, but I can't help it. I just want something to go right, darn it!

Any help/advice would be appreciated!
What is your recipe?

You probably won’t be surprised that my guess is your issues are moisture related. Do you use oil, water, alcohol, or witch hazel?
Humidity plays a really important role,I have found some FOs are not very friendly,
Leaving Citric Acid to the very really helps me, as does sitting for a few hours in the sun (under window), then place in a plastic container with a loose (not sealed) lid, and cover the bombs with a length of tissue paper. these tweeks have all helped in my climate, in my situation.
There is also Lady Luck who is a fickle woman at the best of times.
dont give up
and I only ever use alcohol to spritz (if required at all), water will only activate your mix.
thanks all!

I used witch hazel in my recipe.

I used 1 cup baking soda, 1/2 cup citric acid, 1 tbs kaolin clay, 2 tbs sweet almond oil, 5ml fragrance, sprayed a few times with witch hazel

I think maybe they were slightly too dry when I made them? They were just barely sticking together and I had one in the batch that didn't hold at all. These were also pretty large bath bombs. I used a mold that is 3.5" across so maybe that's another reason? I guess I should look on the bright side - one did hold together and is gift-worthy!

Sandra, I think you had a typo here "Leaving Citric Acid to the very really helps me,"

What did you mean by this? I'm going to try your other advice!
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well, I have not made bath bombs in a while. But my opinion, for whatever is worth, is that you put them in plastic too soon. Bath bombs need to be "cured" like soap, and I would not wrapped them at least in a week. Before a week they are still susceptible to the weather, and weakening. A BB should become hard and strong.

I would not even touch them in a week. The longer the better.
Sandra, I think you had a typo here "Leaving Citric Acid to the very really helps me,"
What did you mean by this? I'm going to try your other advice!

I meant to say ...I leave adding citric acid to the very last ingredient, even after colour and fragrance.
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Do you pack the bath bombs as you go or do you loosly pile the mix in both sides of your moulds (assuming your using mould if not dont worry) and push them together. I have found the cracking happens when you pack as you go.
I package/wrap mine after drying (12 hours-2 days). I have found that if it's humid they will absorb moisture and soften if I don't. I too add my citric until last lately and it works well. I pretty much only add FO's though sometimes I'll use EO.