A fun twist on our homemade play dough soap recipe, this Rainbow Bar Soap is squishy, sudsy and so much fun to add to your kids’ bath time!
Rainbow Play Dough Soap Recipe
Getting my daughter into the bath has always been a struggle, and I know I’m not alone in that!
Making bath time fun with bath tub paints, bath bombs and bath toys sometimes works, but I could probably spend a small fortune on all of add-ons that it would take to make every bath easier so I tend to DIY as much as I can (from making Jiggly Jelly Soaps to cutting shapes out of craft foam that can stick to the shower walls).
Figuring out how to make our own play dough soap (inspired by Lush) has been a fun and super affordable option for bath time. While it can be used to wash hands, in the bath we tend to just use it as play dough. She can play with it as I wash her hair, or just extend her soaking time by making little masterpieces on the side of the tub.
This recipe makes a lot because you’re going to want to throw out the play dough after it gets wet to prevent any mold from growing on the play dough (so I just grab one bar each time).
Our unused play dough soap lasts for a couple of months in a sealed container in the bathroom, or you can keep it in the fridge. If your soap starts to become wet and oily to the touch, it’s time to throw it out and make a new batch.
If you’re worried about the play dough soap clogging your drain, you can use a drain catcher like this one as you empty the bath to catch any pieces of play dough. (We’ve never had any issues with ours as it dissolves really well in the bath.)
Do I have to use castile soap? We’ve now tried the recipe with a few different types of soaps (gel soaps, creamy body washes, etc). I still prefer Dr. Bronner’s Castile soap – it has had the most consistent results and the soap already contains some coconut oil, which helps this soap stay soft.
Can I skip the salt? Salt acts as a preservative, and also adds texture and body to the play dough. It can be skipped, but you dough will be softer and will not last as long. Increase the cream of tartar to help extend the shelf life a bit more. (While we have not had an issue with the salt being “scratchy” I have had one reader comment that she had this issue.)
Doesn’t the food dye stain the bath or skin? We have never had any issues using food dye in our soaps, bath bombs, etc, however you can use soap coloring to dye this play dough soap if you’d like to be sure.
What oils work best in this recipe? We tend to use almond oil (I use it on my skin daily and love it), but olive oil, avocado oil or coconut oil will work well. The coconut oil does harden at room temperature, so your dough may seem a bit more stiff at first but will soften with play.
To make your play dough soap gluten-free, substitute the recipe below for our gluten-free play dough soap recipe.
Check out our quick video to see how to make play dough soap and then turn them into rainbow soap bars – and then don’t forget to scroll down to grab your free printable recipe and instructions:
Rainbow Play Dough Soap Ingredients
- Castile soap (I used Dr. Bronner’s)
- All-purpose flour
- Salt <– if you decide to skip the salt, increase the cream of tartar to 1/2 cup
- Cream of Tartar <– we make a LOT of play dough so it’s soooo much cheaper for us to buy the bulk container of it, rather than the little $4 jars that only last for 2 batches.
- Oil <– almond, olive, avocado or coconut oil all work well
- Food dye, optional <– can use soap coloring
Scroll down to the printable recipe card for full measurements.
Tip: you can double, triple or halve this recipe as desired to make enough bath time play dough for your kids.
Tools You May Find Helpful:
- Measuring cups and spoons
- Large mixing bowl
- Kettle or pan for boiling water
- Wooden spoon or Spatula <– I like these spatulas because they are one solid piece and don’t have removable heads for bacteria to get trapped underneath. Plus they are heat-resistant and have a lifetime warranty.
- Mason jar or plastic container, for storing
- Mixing Bowl
- Measuring Cups and Spoons
- Cutting Board
- Rolling Pin
- Sharp Kitchen Knife
How to Make Play Dough Soap Bars
Start off by boiling your water.
Stir 3 cups of flour, salt, and cream of tartar together. Set aside.
Measure 2 cups of boiling water and add the oil to it. If you are only adding one colour of food dye, you can add it now.
Add 1 cup of the soap. I used lavender Castile soap because it is a pure soap and for the calming effects of lavender during a night time bath. If you try this recipe with a non-castille soap, please let me know how it turns out!
Mix the water-oil and flour mixtures until fully incorporated.
Once the dough has cooled enough for safe handling, start kneading it, adding in more flour to reduce stickiness. Once you get a good texture going, add a couple squirts of castille soap and keep kneading. Add more soap to get a soft dough but stop short of letting it get sticky again. I added just over 1 1/2 cups of soap and probably could have added more (or you can add an extra squirt of soap while your child is playing with it in the bathtub for more sudsy play).
Divide the soap into 6 portions, or as many colors as you want your rainbow soap bars to contain. The outer layer will require more dough, the next layer slightly less, reducing the amount all the way to the center.
Dye each ball of dough with a few drops of soap or food coloring. Kneading well to incorporate.
Roll out the doughs to equal 1/2″ thickness, using a small amount of flour to prevent the dough from sticking to the rolling pin and cutting board.
Layer the rolled out doughs ontop of each other, with red or pink on the bottom, then orange, yellow, green, blue then purple.
Trim all of the doughs to have an equal length, and then trim each layer so that the bottom pink layer has 1/2″ of extra width on each side than the orange layer, the orange layer has an extra 1/2″ of extra width on each side than the yellow layer, etc. (As shown.)
Roll the dough into a log shape, connecting the edges of each layer together. You may want to use a squeezing action as you roll to ensure the layers stick together.
Use a sharp knife to cut the log into soap bars.
Grab your free printable recipe for our homemade play dough soap bars:
If you need the play dough to be gluten-free, swap out the recipe above for: As an Amazon Associate and member of other affiliate programs, I earn from qualifying purchases.
If you need the play dough to be gluten-free, swap out the recipe above for:
As an Amazon Associate and member of other affiliate programs, I earn from qualifying purchases.
I hope your kids love these play dough soap bars as much as mine does – and that it makes bath time battles a little less frequent!
For more fun Bath Time DIYs, check out our full collection of DIY Beauty Ideas here:
Or, check out some of our other Play Dough Ideas here: