Tuesday, April 12, 2011

An aside: Shelf lives of our products (part 1)

I'll be getting back to duplicating products in a few days, but I thought this was a really important topic for learning how to formulate and duplicate!

Will commented in this post...I use liquid germall plus in my own concoctions and haven't noticed anything go bad, but I typically use a batch of lotion within a month, so that's probably not surprising. On the other hand, I've purchased products (gasp!) and haven't used them within a couple of years, and they "seem" to be still good. I'm sure I'm not the only guy that does this sort of thing. I think many lotions are purposely made with mineral oil and such so that rancidity is less of a concern. Anyhow, knowing something may sit for a long time, here's my question -- is a single preservative like germall plus truly sufficient or would adding in a second preservative really be best? If yes, what would you recommend? Yes, I am a little bit of a germ-a-phobe.

We're all germ-a-phobes around here when it comes to lotion making, Will! It's the safest way to think!

To answer your question, a good broad spectrum preservative will last the life of your lotion, long after your oils have gone off. Most have shelf lives of two years. You can combine preservatives to create a broader spectrum preservative - for instance, adding something like one of the organic acids (which tend to be good fungal killers) with Optiphen - or you could do something like add liquid Germall Plus at 0.25% (range 0.1% to 0.5%) with 0.5% Germaben II (range 0.5% to 1.0%) to cover all your bases if you have something especially hard to preserve. I use liquid Germall Plus at the maximum 0.5%, and I've found my oils will go rancid long before I have any preserving problems, so it's not like someone's going to use it! (Believe me, if you've ever smelled rancid products, you won't accidentally use them!).

Will's question leads me to another thought...I addressed the idea of figuring out the shelf life of your products in this post, but I thought it was a good idea to re-visit it and think more about the ingredients we could use to extend the shelf life of any product.

Quick summary: The way to figure out your shelf life is to look at your shortest lived ingredient and figure that'll be the shelf life. So if you're using grapeseed oil, you'll have a three month product. If you're using olive oil, it could be up to a year. Look at each ingredient and figure out how long it has in the product. I mean every ingredient - glycerin, extracts, hydrosols, oils, butters, and so on. For the most part, the main concern will be the oils and butters as most preservatives have a two year life span. Write the date you opened the oils on the bottle so you know how long you have left. If you bought that container of grapeseed oil two months ago and opened it then, you've only got one month left. (And this is the reason I don't use grapeseed oil!)

One of the reasons we see mineral oil and petroleum in so many products is thanks to its shelf life. Both can last for years before going rancid, whereas most of our oils have a 6 month to one year shelf life. And shelf life is another reason we see a lot of our natural oils coming in at tiny percentages when they are used in a commercial product.

When we're working with natural oils we will have a year or so maximum for our products. We can add all kinds of things to extend the life span, but we're not going much over a year. For butters, most have a two year life span, but that's irrelevant if you're pairing them up with short lived oils.

Want to know the shelf life of your favourite oils? Please check out these posts on oils (under the emollients tag in the links to pages section) or the charts for more information. (If you click on the link for all the posts, you'll see charts for exotic oils and butters as well!) 

Join me tomorrow as we take a look at the shelf life of a few recipes then think about how to extend them!


Anonymous said...

I have just arrived to your blog and have to say it's really interesting! In fact I am also quite interested in cosmestic chemistry.
I'd like to ask you something: do you know any brand working with mineral make up which only includes serecite in their productos composition? My skin is oily and I am suffering of acne so I should avoid all the ingredients (as talc, for example) except serecite, zinc oxide and titanium dioxide, but, about the last ones I've read that release free radicals on the skin... however, if i cannot avoid them I'll try to use a base with antioxidant actives...

Thank you so much!
I'll be reading you!


p said...

I've been wondering for a while about this topic. When I try to calculate a shelf life for a product I've made, I look at the ingredient with the shortest shelf life... but then what? How does adding 1% vitamin e or rosemary oleoresin affect the shelf life of that ingredient (which is usually an oil)? And how does refrigeration affect the shelf life of our oils?

For example, if I buy rosehip seed oil (a 6 month shelf life oil) now in April, refrigerate it until I open it in June to make a product, to which I add 1% rosemary oleoresin, when is my product good until? I've been assuming it's good for well over 6 months past the date I made the product, because of all that antioxidizing power - though this estimate matches my experience of my creations going rancid, I realize now I'm sort of pulling that shelf life out of thin air.

How do we turn our techniques for preventing oxidation (refrigeration before using, adding antioxidants) into an estimated shelf life? Maybe you're planning to address this already - if so, sorry for my impatience!

p said...

p.s. Lau - Monave is one MMU company you might find helpful. http://www.monave.com/

Susan Barclay-Nichols said...

Hi Lau. I'm sorry but I have no idea about commercial mineral make-up. I make my own, so I've never used any other products. Why not try making your own? You'll find a ton of recipes under the link MMU (click here) and it's great fun, as well as much cheaper than buying it!

I wonder how your skin would handle Micronaspheres? They're great for oily and acne prone skin! And here's the link to the post on sericite mica.

Anonymous said...

Maybe I should try, then.

But... you buy the minerals already tinted (or with different natural pigments...)and then mix them to obtain different colors or tones, right?

Maybe this would be a good solution for me. Thank you so much for the information!

I'll finish reading your entries about homemade mineral make up and decide.

Thanks a lot for the web, P; I'll check it.


Anonymous said...

thanks for this post. i just purchased leucidal liquid and will pair it with an organic acid to be on the safe side. i plan to use it for a product that will be made shortly that is just hydrosols and extracts for a persistently itchy scalp.

great post as usual.