preservatives & antioxidants

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there's a lot of available data regarding preservatives, and it can be overwhelming. perhahps the following information about the commonly available preservatives and antioxidants will prove useful and clear up some of the confusion about what a preservative is and when it should be used.
unfortunately there are no all-natural preservatives. in order to produce a safe product that is free of bacteria, mold and yeast, it is necessary to use a chemical preservative.
preservatives / antioxidants -- what's the difference?
it's important to know the difference between antioxidants and preservatives. they are both useful, but perform different jobs. a preservative is used to kill and inhibit growth bacteria, mold and yeast. these can be dangerous. you only need to think of e-coli or staph to know this. lotions and other cosmetics are the perfect breeding ground for these microorganisms, since they need water to survive and reproduce. combine that with the warm, damp environment of most bathrooms, and an unpreserved product could be potentially dangerous to your customers.
an antioxidant is used to prevent the oxidation of oils and fats. oxidation results in rancid oils. rancid oils are not dangerous, nor do they harbour micro-organisms. they just smell bad. an antioxidant will not prevent micro-organisms from growing in your products, yet they are still helpful in keeping your products fresh. antioxidants may be helpful in soap, but they are not necessary, since the oils are no longer oils, but soap. they are recommended in soaps that have high superfat percentages or soaps with high amount of oils with short shelf lives.
products that need preserving
preservatives are necessary for keeping vulnerable products fresh and free of bacterial growth.
bacteria, molds and yeast can't thrive without water. if your product contains water or if water may be introduced into the product, then a preservative is needed. usually, products without water, (such as a balm or a salve), will not need preserving. however, depending on the intended use of the product, it is possible that a customer could introduce water (via wet hands), in which case the product is then vulnerable to the growth of bacteria, mold, and fungus, and should be preserved as a precaution.
all mixtures of oil and water (i.e. lotion) need preserving.
note: all [lotion] formulas should be tested before offering them for sale to the public ...preferably challenge tested*. by theory, all of the preservatives listed below should work, however, some preservatives work best against bacteria, while others specialize in fungus and mold. most work only in narrowly defined ph ranges. some special cases may require a combination of preservatives. there is no way to know for sure without testing.
* (they actually introduce germs and other nasties into the product and see if they grow ...if they don't, your product is safe.)
challenge testing is prohibitively expensive and not at all practical for the home crafter. there are, however, other alternatives.
• "dr. cindy jones" from "the sagescript institute" provides testing designed for the home crafter very reasonable rates. This is not the "challenge" test, but she does offer an apc tests (for bacteria) and a fungal/yeast test (for fungus and yeasts).
• another alternative is the home testing kit available from "snowdrift farms". again, this is not a "challenge" test, but provides a way to determine if your working process is in some way introducing [unsafe levels of] contaminants into your product.
soaps usually doesn't require preserving, since the oil is converted to a salt during saponification. as for any remaining oil (i.e. superfat), the ph of the soap itself is inhospitable to germs and fungal growth. however, it may be prudent to preserve the soap if you've purposefully lowered the ph (i.e. tearless shampoo), you've incorporated botanicals or food stuffs (e.g flower petals, pumkin puree, etc.), or it has a very high superfat (above 10%).
common antioxidants
  vitamine e natural vitamin e (t-50) has been shown to be extremely helpful in preventing rancidity in oils. it is a good idea to add vitamin e to products containing oils with short shelf lives, like hemp seed oil, sunflower oil, apricot kernel oil, grapeseed oil and sweet almond oil.

rosemary oleoresin extract (roe) is not to be confused with rosemary essential oil. roe is a thick green liquid, and it has a slight odor of rosemary. while there haven't been many studies done on its efficiency as an antioxidant, it has been shown to be very promising. used in the same manner as vitamin e, it will help keep oils and products containing oils from going rancid.
common preservatives
  cosmocil cq cosmocil cq has recently received world-wide approval and is now available (from "lotioncrafter" and "snowdrift farm"). this new preservative is parabens free and does not release formaldehyde.
like phenonip, cosmocil cq can be used at higher temperatures -- up to 284°f (140°c), but unlike phenonip, it is low-odor so you won't have to deal with camouflaging the smell. unfortunately, cosmocil cq is only water soluble (add to the water phase), so unlike phenonip, it's not miscible in oil and can't be used in an all-oil produce (e.g. salt/sugar scrubs). the usage rate ranges from .5% to 1.5%, with the typical usage rate being 1% of your total formula.
cosmocil cq is composed of and should be labeled as: polyaminopropyl biguanide. you can view the "bulletin", which gives an overview of the product. i'm making this smaller (74k) .pdf document [from avecia biocides] available here on this site. a larger (338K) much more "technical document" [from arch personal care products] is available on their site.

  germaben germaben II is a well known preservative that has been shown to be very effective and is compatible with most cosmetic ingredients. germaben is soluble in water, so your products must contain water in order for it to work. the typical usage rate is 1% of your total formula. it starts to decompose at 100°f, so it should be added to your formula after it has cooled below this temperature. adding it at higher temperatures may compromise it's ability to fight off germs.
germaben II is composed of and should be labeled as: propylene glycol, diazolidinyl urea, methylparaben, propylparaben.
germaben II is for use in products with an oil/butter content of 25% or less. for higher percentages use "germaben II-e". germaben II-e was developed for creams and lotions that present special preservation problems involving partial inactivation of parabens by ingredients in the formulation.

  germall plus germall plus is available in powder form or as a liquid. it works much like germaben II in that it is compatible with most cosmetic ingredients, and it is water soluble. it will not work in formulas that do not contain water. it should also be added to your formula during cool down. the powdered form of germall plus should be used at a rate of .2% of your total formula.
germall plus is composed of and should be labeled as: diazolidinyl urea, iodopropenylbutacarbamate.

liquapar optima is a broad spectrum preservative used in a wide range of cosmetic products such as: creams, lotions, scrubs, shampoo, and liquid soap. liquapar optima is similar to phenonip in several respects: it can be used at higher temperatures and it can be used in an all-oil formulation.
liquapar optima can be used pre or post emulsification. it is also non-volatile, remains fully stable over a wide ph and temperature range, is non-irritating to the skin, eyes, and mucous membranes, is devoid of skin sensitizing effects, is biodegradable, and presents no pollution hazard.
owing to its many advantages, liquapar optima is suitable for the preservation of topical pharmaceuticals and cosmetic and toiletry products of all types. its powerful microbiocidal activity in most systems makes it effective in those products, which have been found especially difficult to preserve in the past (shampoos, lotions, creams, and protein-rich systems.) liquapar optima should be used at a rate of 0.5% - 1% depending on the conditions.
liquapar optima is made of phenoxyethanol, methylparaben, isopropylparaben, isobutylparaben, and butylparaben

  phenonip phenonip is a clear liquid that works in a multitude of applications. it's unique in that it's soluble in oil and dispersible in water. this preservative was designed with cosmetics in mind and is especially effective when used in conjunction with oil based products but also works extremely well in aqueous solutions. this means that it will also work in products, like balms and salves, that contain only oils. phenonip is also able to withstand a broader temperature range. tests show that it can be heated to sterilization temperatures with out degrading the quality of the preservative. it works in a wide ph range of 3 - 8. the usage rate varies from .3% to 1% of your total formula. (depending on the application), while most applications call for a rate of .3% to .5%.
heat water to between 140°f and 158°f, dissolve citric acid and glycerin, and add phenonip. this step is important because it gets the phenonip properly dissolved in the water. otherwise it would tend to dissolve in the oils, where it would not be as effective at retarding bacterial growth. this recommendation comes directly from the manufacturer.
phenonip is composed of and should be labeled as: phenoxyethanol, methylparaben, ethylparaben, butylparaben, propylparaben.

  suttocide suttocide is a broad-spectrum antimicrobial active against gram-negative, gram-positive bacteria, yeast and molds. it's unlike many of the other available preservatives in that it is effective under alkaline conditions ...up to ph 12. this makes it an ideal preservative for soap. it is also effective in an acidic environment. in a synergistic partnership with other preservatives (liquipar in particular), it's very effective for preserving complex formulations.
suttocide should be used at a rate of 0.1% - 1% depending on the conditions, and should be labeled as: sodium hydroxymethylglycinate.
note: suttocide will react with citral, (a component of some essential / fragrance oils), and affect a color change in the formulation from light pink to a deep red (modified, of course, by whether the formulation is clear or opaque and also by whatever other color is present).
this change doesn't happen all at once; it occurs gradually over [about] two weeks. the degree of the color change is dependent on the amount of citral in the essential / fragrance oil(s), and the amount of essential / fragrance oil(s) used in the formulation. those essential oils containing citral are those with lemon odor characteristics: lemon, lemongrass, lemon myrtle, litsea cubeba, orange, verbena, etc.
the solution to this problem is simple; when using suttocide as a preservative, don't use a fragrance containing citral.
what preservative should i use?
many people have asked me this question and i always avoid any recommendation. the choice of any one particular preservative (or combination) over another is made according to personal preferences and requirements.
in addition to the ph of the product and temperature at which the preservative is being used, there are the considerations of the product's intended use as well as it's ingredients.
there is also the question of safety. some preservatives are made from parabens and/or formaldehyde-releaseing substances (e.g. diazolidinyl urea), which are considered [by some] to be toxic and carcinogenic.
are they safe to use? well, it's like the case with saccharin. it's been approved for human consumption since the quantities being used are far less than those shown to cause cancer in rats. yet, there are those who feel since the product has the potentiality of being carcinogenic, they avoid it. many substances are available to us under these circumstances. a lot of ingredients used in cosmetics fall into this category. whether or not to use them is a personal choice ...which should be a well-informed one.
for more safety information, lotioncrafter's "technical page" provides a msds for [most of] the preservatives listed above.
you can also check out "international specialty products" (isp), where you have access to even more indepth technical and usage data (including the msds) for the various preservatives, which include [most of] the ones listed above ...they don't have any data for cosmocil or phenonip. they do, however, offer information on liquagard, and optiphen, (not listed above).
preservative myths
myth: grapefruit seed extract (gse) is an all natural preservative -- there are rumors over the web that grapefruit seed extract works as a natural preservative. this is not true. there was a study done on the preservative qualities of gse. this study found that it had been contaminated with triclosan and other chemical preservatives. the study also took a handmade grapefruit seed extract that was not tainted with other chemicals. this sample showed zero preservative qualities.
myth: essential oils will work as preservatives -- while it is true that some essential oils exhibit antibacterial and anti-fungal qualities, the quantity needed to effectively preserve a product would put the essential oils at unsafe levels. it is best to save the essential oils for fragrance purposes only.
myth: potassium sorbate is an all-natural preservative -- while potassium sorbate can effectively preserve against mold and yeast, it is not useful for protecting the product from bacteria. it is also not effective at all in products with a ph over 6, which most lotions are. while potassium sorbate is found in nature, any available today would have been synthetically made so it is not all-natural. it is also believed to cause contact dermatitis.
unfortunately there are no all-natural preservatives. in order to produce a product that is free of bacteria, mold and yeast and a product that is safe for your customers it is necessary to use a chemical preservative.