heating and holding, Nedeia asks: What could go wrong if you heat your ingredients at more than 70 degrees, say 80? I do not have a crock pot , and the best way I have found to get the 2 phases at the right temp at the same time, is to place them into a bowl of hot water. they get to 70 degrees or a bit more, but I cannt hold at 70 for 20 minutes, the water will cool down eventually, and constantly heating it from time to time is not an option for someone that also needs to watch a kid :)
Using a 0.5-1% Optiphen would keep the lotion mold and germ free for a period of time, so... could I skip the hold period, especially because I cannot control the temperature without the risk of "burning" the oils?
You have two questions here, so let's take a look at question number one: What could go wrong if you go over 70˚C to 80˚C when heating and holding?
The short answer is that going to 80˚C isn't a bad thing when heating and holding, but I wouldn't want to go over. The long answer is this...
All oils have a smoke point and we don't want heat our oils above that point, but they really aren't that fragile! For instance, camellia seed oil has a smoke point of 485˚F or 251.7˚C, grapeseed has a smoke point of 420˚F or 216 ˚C, and even flax seed can handle 225˚F or 107˚C (one of the lowest smoke points). As you can see, these oils can handle temperatures far higher than our heating and hold temperatures. (Click here for a handy dandy chart on smoke points from Wikipedia!) So leaving them at 70˚C/158˚F to 80˚C/176˚F for 20 minutes won't burn them or ruin the awesome power of their fatty acids!
Having said this, just because the oils can handle a little bit more heat doesn't mean we should heat our other ingredients up to higher levels! I wouldn't want to go over 80˚C for things like my water phase - more evaporation isn't a good thing - and I wouldn't want to expose my emulsifiers to something more than 80˚C. But it is safe, for the most part, to go over 70˚C when you're heating and holding. (Yes, there are some ingredients that we don't want to heat and hold and some that don't want to be over 70˚C, but I can't go into every ingredient in this post!)
Just make sure your two phases are around the same temperature when you add them. If your water phase is at 60˚C and your oil phase at 80˚C (or vice versa), this can lead to epic lotion failure. If you can get them within a few degrees of each other, all should be good!
There are a few different reasons to heat and hold our heated water phase and heated oil phase. The main two are to eliminate possible contamination and to get our ingredients to the phase inversion temperature so we can have an awesome and stable emulsion. (Click here for a lengthy post on heating and holding and click for another one on heating and holding the phases separately. Click here for a post on how and why lotions fail.)
I don't consider heating and holding optional. It is necessary to ensure we get a safe, stable lotion. If you don't have a crock pot, get something like one at a thrift store. (I could get you at least three crock pots at my local Sally Ann's for $10 each!) You can create a double boiler using two pots on a stove, but if you've got a little one running about, that's probably not an option either.
As for the second question - can you skip the hold period? - no. Yes, your preservative will work to stave off contamination, but you need to heat and hold the lotion to ensure you start with lower levels of contamination. We are never going to get rid of the bacteria, yeast, and other nasties entirely because they're everywhere in the environment, but heating and holding can substantially reduce those nasties! Why start off the shelf life of your lotion with ickiness when it's so easily avoided? (Although, having said this, Optiphen is not considered a broad spectrum preservative, so there's always the chance of mould!) As well, don't you want a well emulsified lotion?
Sucragel AOF. I find this product limited in that I can't make a thick lotion and it feels sticky, but it can be used without heating and holding. I have no idea how much it costs or where to get it - Susan from Saffire Blue sent me samples of it for posts for her blog, but I don't see it in her shop yet - but if you really can't find the time or equipment to heat and hold, this might be an option! (Click here for the video on how to use it!)
To summarize this post in a few sentences: You can go higher than the heating and holding temperature of 70˚C/158˚F without ruining your oils, and heating and holding is an essential part of lotion making to reduce the risk of contamination and to ensure we make a good lotion.
Join me tomorrow for more fun formulating!