Quick chemistry reminder: Lotions are formed through chemical, mechanical, and heat emulsification, so most of our questions will revolve around the issue of emulsification.
Review your recipe. Write down the size of the oil phase, the water phase, and the cool down phase. It should add up to 100%. If it doesn't, take a look at what could be reduced - normally the water phase.
If it is written in volume - tablespoons, teaspoons, cups, and so on - don't make this recipe. It's simply not accurate enough so you can replicate it next time. You want a recipe written in weight so you can be sure you have the same measurements every single time. A tablespoon of emulsifier could be short one time and over the next. Accuracy is important!
How do I know if it's a good recipe?
Why do we weigh our ingredients?
How to convert from percentages to weight?
How to convert from weight to percentages?
How much emulsifier did you use? Every emulsifier has a suggested usage rate, and I recommend using the higher level of emulsifier if you're new to using it. For Polawax - and Polawax only - there's a 25% oil phase rule of thumb for its usage. If you have 20% oils, you will use 5% emulsifier (multiply your oil percentage by 0.25 to get your amount!) If you're using something like BTMS-50, you don't have to use the 25% oil phase amount, but it isn't a bad to start. I know with something like Ritamulse, I used 8% every time because I couldn't find a suggested usage rate from anyone, but I kept seeing this amount in the sample recipes from the company (never 7%, never 9%, always 8% regardless of the oil phase...weird!)
As an aside, some emulsifiers don't play well with other ingredients. Check to ensure your emulsifier can play well with cationic or positively charged ingredients, different preservatives, and extracts. (Using Optiphen as a preservative can cause some problems with curdled lotions!)
Did you actually use an emulsifier? If you used beeswax as the emulsifier in your product, you won't get emulsification.
Related post: Beeswax is not an emulsifier.
heat and hold both the heated water phase and heated oil phase at 70˚C/158F for 20 minutes? If you didn't, then go back and try the recipe again and do that. The majority of fails I read about this morning were from people who didn't heat and hold.
I'm really confused about why heating and holding is a controversial subject. I saw the owner of a forum tell the readers that we were wasting our precious "life minutes" heating and holding and that it ruins the oils. It does not ruin oils and we aren't wasting time heating and holding as it's an important part of the process for the chemistry of emulsification - read this post if you're interested in learning more - as well as the preservation of the product.
Did you add the water to the oil phase or the oil to the water phase? Turns out that really doesn't matter much for us homecrafters!
Did you wait until the product cooled down to 45˚C/113˚F before adding the cool down phase? When I made a lotion with Ritamulse, I added my preservatives and cool down phase at 50˚C (which is fine for Polawax) and it curdled almost immediately! Eek! A kilogram of lotion ruined!
Related post: Cool down phase
Did you add some oils into the cool down phase without heating them? There's this idea going around that some oils are too fragile to be heated and held. This is simply not true. Oils can withstand a ton of heating, and the various things we find in oils - polyphenols, phytosterols, fatty acids, vitamins, and minerals - can handle being heated and held at 70˚C. If you add them to the cool down phase, you may see some separation!
Heating, holding, and thawing our ingredients!
Does heating & holding hurt our oils?
Questions about mixing.
Combining the two phases: Mixing
Ask yourself these questions and I think you'll find the answer to why your lotion failed. Fails are normal and part of the process. I know it feels like you're wasting supplies, but think of how much you've learned from just one separated lotion! You've learned about emulsifiers, heating and holding, measuring by weight, choosing a good recipe, mixing, and everything else. It's worth the frustration and garbaged supplies if you can make an awesome lotion next time!
Related posts for this post:
The chemistry behind why lotions fail!
An example of lotion fail!