Monday, October 14, 2013
Long Weekend Wonderings: When to add Vitamin E and essential oils? How much fragrance or essential oil to use in a product?
In this post on anti-oxidants, Rachel asks: Can you please let me know at what temp you would add Vitamin E and EOs to your lotion bar? I added Vit E at 65˚C and it started to set around the globules and was difficult to mix in. The manufacturer says to add EOs at 55˚C, but I've been adding them at 65˚C because if it was cooler it wouldn't pour properly.
I tend to end up adding Vitamin E in the cool down phase of my products mainly because I tend to forget to add it and remember when I'm just about done, but it is heat stable, so can be added to the heated oil phase of our product. (Reference: Data sheet from Lotioncrafter). As for why it might have turned into globules - you're adding something cold (room temperature) to something warm, and this can be a problem. Heat it up by putting into a little warm water before adding it. Or just add it to the heated phase and you won't have this problem.
Always add fragrance or essential oils at your cool down temperatures of 45˚C or lower because they are volatile, meaning that heat isn't their friend, making them evaporate into the atmosphere instead of staying in your product. You can heat them up to that temperature to add them instead of having them at room temperature when you combine them into the product.
How do you know when to include an ingredient?
In this post on bath melts, Tania asks: About this recipe you say 1 or 2% FO or EO, is this the percentage of the total weight of all the ingredients, or only 1 or 2% of total weight of the butters?
The fragrance or essential oil are always used at a percentage of the total recipe, as are all ingredients. If you have a recipe that totals 100 grams, you'd use 1% to 2% fragrance oil, so you'd use 1 gram to 2 grams of your favourite fragrance oil. If you have a recipe that works out to 200 grams, you'd use 1% to 2% of the total amount, which would be 2 grams to 4 grams of fragrance to essential oil.
How do I know how much of an ingredient to use in a product?
How convert recipes from percentages to weight?
Calculating percentages in lotions
In this post on pH and lotions, Shelly asks: I had a question regarding pH testing on lotions as well. I bought your ebook through Lotioncrafters and I have been following them exactly. I do notice that the lotions seem to burn when applied to the face. I tested some recent lotions and they were coming in around 4. I know lotions should be around 5-7. I got water on my pH meter and it shorted out so I have to buy a new one. It is confusing on which type is appropriate for lotions and do they need to be calibrated to get accurate readings?
There are so many variables in a lotion, it's hard to make the same product twice even when made in the same workshop by the same formulator, so your results will always vary from mine no matter how close you try to get the ingredients. (Which is why I ask for the recipe and process when someone is asking for help!) When I check the pH of my lotions, I strive for 5.5 to 6 as this is where my skin prefers the products, so all my recipes should reach those levels. But your mileage may vary, and that's why I hope I offer enough information to make whatever changes you need.
Water has the most impact on the pH of the product if it's the most abundant ingredient. Distilled water should have a pH of 7, while reverse osmosis could be 6.5 to 7, alkaline water is well over 8, and tap water could be as low as 6.5, depending upon what's in it.
The ingredients you choose will have an impact on the pH of the product. The oils and butters won't change anything, but things like preservatives, chelating ingredients, cosmeceuticals, and so on will alter the pH slightly here and there.
Botanical ingredients aren't the same from batch to batch, so using bottle A of rosemary hydrosol from your favourite supplier isn't necessarily the same as bottle B from a different supplier or different batch number. I've had rosemary hydrosol register at 6.6 and at 5.7 - these aren't small differences!
This is one of the reasons the big companies use mineral oil: It's easier to standardize this ingredient!
Cosmeceuticals are intended to be used in facial moisturizers, and quite a few of them are either quite acidic in nature because they are exfoliating in nature, something that requires a lower pH (like AHAs).
Some preservatives are acids, so using those may reduce the pH level of your product.
Most of the ingredients we use in a lotion are acidic, so combining one with another and another means the pH can get lower than we want. This is when we alter the pH of our products by using an alkaline ingredient like EDTA or sodium hydroxide.
Questions about lye...
Chemistry Thursday: Chemical reactions
This is one of the reasons I encourage you to check your pH at home, if you can. Don't be too worried about it if you aren't having any adverse reactions to your products; it's just something to think about if you are.
Calibration is essential to accuracy, and I encourage you to do it regularly. Read the instructions for your specific machine and complete the process exactly as suggested. I do a two point calibration - pH 4 and 7 - because I can't find pH 10 buffer solution, but more is always better. I bought mine at my local hydroponics store, which is the easiest place to find these things. (Or try a garden shop if you really feel uncomfortable with the hydroponics shop!)
I failed to calibrate my machine after leaving it for a while, and I ended up making a seriously acidic product because it was reading a higher pH than the product actually was! So dangerous!
Having said all of this, pH of our products is essential, so if the lotion is stinging you, stop using it and check the pH of the next batch. Check the data bulletins for your product to see what the pH of every ingredient might be. You can't really do the math on it, but it might be you're using something really really acidic in the product that is enough to throw off the results. Or it could be you're using water that is really acidic.
Please write to me personally if you want to talk about the recipe some more. Please send me your exact recipe with specific ingredients (INCI names if it isn't obvious what they are) and your process and I'll see what I can do!
Chemistry Thursday: How to measure pH?
Chemistry Thursday on Friday: Let's take a look at pH
A thought for the day: ...pH of our bodies
Chemistry of skin: pH and the skin's acid mantle
Join me tomorrow for more fun formulating with gels!