The Simple Guide to Coloring Your Bath Bombs
We all want our bath bombs to draw attention, and that's why we create icings, frostings, add colored salts, dried flowers, sugar sprinkles, glitter, etc. But the question I get asked the most is "What colorants can I use for my bath bombs?". The thing is, there is not just an answer to this question and your options may also vary depending on where you live and whether you want to sell your bath bombs or not.
I will try to lay the information as detailed as possible but if I miss something don't be shy and let me know so I can update this post.
So, the boring stuff first and then we're going to go to all the fun.
1. Before you start making bath bombs you should ask yourself a question if you want to sell your bath bombs. If the answer is yes then you should check up with the cosmetic regulations of your country. For example, you are only allowed to use FDA&C certified colorants for bath bombs in the US. If you only make them for yourself and family then it's ok to use not batch certified colorants but they still should be skin safe.
2. Are you going for a "natural" look? Do you want to use "all-natural" ingredients? If so, then you should research what the word "natural" means in the context of cosmetics because in the countries like the US the term "natural" is not even legally defined. I can't stress enough how important it is to do your research when it comes to this topic and you're going to hear so much conflicting information that you might get lost in the world of scary words like "toxins" and "chemicals". Once you define what ingredients you're comfortable working with you can move to the next step.
Since we have all that cleared up we can start digging into the rabbit hole of colorants. I am going to speak about the most known and used ones.
Fruit Powders - they're not technically colorants but if you go for a more "natural" look you can use clays, fruit powders (beetroot powder, orange peel powder), and even cocoa powder to slightly color your bath bombs.
Water-soluble dyes (powder)- are very potent and super-concentrated colorants with a great color payoff. Just a tiny little amount will give your creations a vibrant color and won't stain your bathtub! Just for a reference, I need about 0.04-0.1 g of powdered dye per 500g bath bomb batch to get a nice vibrant color. However, they are in the higher price range but because water-soluble dyes are so concentrated you don't need to use a lot so even a 5g pack will last you quite a bit. Water-soluble dyes are a perfect option if you want your bath bombs to color the water. Make sure you buy batch certified dyes if you're planning on selling your bath bombs and other products.
Because dyes are water-soluble you need water to "activate" their color. I'm familiar with two techniques on how to work with dyes but I'm sure it's not the limit.
a) "blooming" - adding your dyes and some water to baking soda, mixing and letting it completely dry before adding the rest of your ingredients.
b) mixing the desired amount of a certain dye with 2-3 ml of hot, boiling water and slowly adding it to your bath bomb mixture while constantly mixing. That's how I work with dyes because I'm way too impatient to wait until my bloomed baking soda will dry.
Both methods work very well so you could try them and see which one you prefer.
LAKES (powder) - are oil-soluble colorants. They are very easy to work with. Lakes have a lower dye load which means you'll need to add more colorant to get a deep, vibrant color. You can add your lakes directly to your mix but make sure you're using Polysorbate 80 in your recipe. It will help to disperse your colors and oils, without Polysorbate 80 I used dyes and lakes to color these bath bombs.
MICAS - minerals with added oxides and dyes to give them color. They come in an abundance of different colors. Micas don't need batch certification and they're cheaper than dyes and lakes. Yet, this type of bath bomb colorants is less potent than dyes or lakes and they won't color your water much. However, if you want your bath creations to have that cool shimmery effect then mica is what you need. Polysorbate 80 is a MUST in a bath bomb recipe when you work with micas. If you don't include Polysorbate 80 in your bath bomb formulation mica will not only stain your bathtub but, potentially, even your skin. Make sure to avoid micas with ultramarines because when added to a bath bomb they make your bath fizzies smell very unpleasantly.
It should be noted that you don't have to limit yourself to just one colorant type. You're going to have way more options if you combine dyes and micas, micas and lakes, lakes and dyes, etc. My absolutely favorite colorants of all times are water-soluble dyes but I also use micas and laces for many bath and body projects including bath bombs.
LIQUID COLORANTS - predisposed in oil or glycerine. I personally wouldn't use liquid colorants for bath bombs especially the ones dispersed in glycerine. Glycerine is a humectant which means that it draws the moisture into your product which could sett off a fizzing reaction prematurely. I am not saying these colorants are bad or not worth giving a try. If it sounds like something you might be interested in, you could check the list of suppliers that I have on my blog, many vendors carry these colors and I am sure that there are crafters out there who successfully use liquid colorants.
PROTIP - if you're serious about making bath bombs or, for that matter, any other bath or skin products, and your goal is to eventually sell your creations then you need to track your supplies, recipes, batches, costs. In particular, there's no way to figure out how much it costs you to make a bath bomb if you don't weigh all of your ingredients even dyes. I use scales that measure down to 0.01 grams to measure my dyes, preservatives, and actives for creams and lotions, etc. You get them on amazon for 10-15$.
I recommend using Airtable or even Spreadsheets to keep track of your inventory, costs, batches, recipes. I have a blog post on how to use Spreadsheets to calculate your recipes in %. I have more information on Airtable on my Software page so if you're struggling with your inventory and recipes being all over the place you should give it a quick read.
I also have a list of suppliers on my blog so definitely check it out!