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Getting Started with Formula Development

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So you've got oils, butters, emulsifiers, preservatives and actives. Now you're standing at your, newly created, work area and think ... WHAT NOW? How do I decide how much of these to use? How do I calculate this? How do I measure this? How do I stir this? How do I test this?

These are the questions that every formula developer will have to face, right off the bat, and we're happy to help you answer those questions and take some of the initial stress away.

Be sure to check the end of this document for local suggestions and supplier links to help you find the supplies and equipment necessary for making your formulations and emulsions.

Determining the amount of each ingredient you will need is fairly straightforward:

  • check the usage 1guidelines supplied by manufacturer
  • decided where your desired outcome puts your requirement within the usage range
    • preservatives ? these always have a usage range and the best way to determine your formulation requirement is always to have your product tested, when your product is finalized and then make modifications to 2optimize your levels but, here are some tips to get you started
    • if your formula will contain ingredients, especially botanicals such as aloe, milk, etc., that create a, higher than usual, challenge to the preservative then you will need to use the maximum amount recommended to be sure that it is adequately protected from mold and yeast, you can then decide if you'd like to have your formulation tested to determine whether, or not, the level can be reduced
    • if your formula does not contain any high challenges, especially if a lot of your actives are already preserved during their manufacture then you can start at the levels that are published, and shown to be effective, during the manufacturers testing of the preservative, for instance...in every test that the manufacturer has done using Geogard Ultra the level was at 1.0% and it was shown to be effective
    • we recommend that you never start at the low end of the suggested usage, this level is only for optimizing your preservative level after finalizing your formulation
  • emulsifiers ? the recommended usage for these is a little harder to determine when starting out but it can be accomplished, without resorting the the antiquated 3HLB system, with a little research...
    • look at the manufacturers recommended usage and make a small test batch using a level somewhere around the middle of the range and them make adjustments based on the outcome of your sample batch
    • read through published sample formulas to learn, through proven science, what levels have been necessary based on the ratios of oil to water and similarity to your desired product and chosen ingredients
    • read, and understand, the behavior of your chosen emulsifiers in order to make educated choices regarding thickeners, emollients, oils and butters
  • actives ? this is an easy one...if you want the highest level of activity and are comfortable with the cost of the material then you can just use the maximum recommended usage for that active. If you need to bring down the cost then you can try a small test batch at the lowest recommended usage rate and adjust if necessary
  • oils / butters ? this is not as easy but, is also doable without resorting the the HLB System
    • a good rule of thumb is that the closer you get to a 50 / 50 ratio of water and oil the harder it will be to emulsify (the mixing together of two immiscible / nonblendable ingredients
    • creams are generally a mix of approximately 70% water and 30% oils / butters
    • lotions are generally a mix of approximately 80% water and 20% oils / butters
    • thickeners will help hold the emulsification together
    • adjusting the pH to an acidic level will help hold the emulsification together
    • combining the water and oil phases together hot (170oF) and at the same temperature will help hold the emulsification together
    • the additions of rheology modifiers that turn the water phase into gels will help hold the emulsification together
    • stirring throughout the cool down time will help hold the emulsification together
    • faster cooling (immersing the bowl in a 50 /50 mixture of ice and water) will help hold the emulsification together

Calculating the amounts to use is just a matter of doing the math and the conversion:

  • Determine what percentage to use of each ingredient
  • Determine whether each ingredient is water soluble or oil soluble
  • Calculate that percentage based on the batch size that you'd like to make
    • let's say that you want to make a cream and the ingredients you want to include, based on their activity are; Aloe Vera Juice, Shea Butter, jojoba, Apricot Kernel oil
    • let's say that you want it to have anti-inflammatory activity so you choose to add Allantoin and Panthenol
    • let's say that you want it to be preserved naturally so you choose Geogard Ultra
    • let's say that you prefer to use a stand alone emulsifier and want it to be vegetable so you choose Emulsifying Wax NF
    • let's do the research....
      • we discover that Aloe Vera Juice is pure electrolyte and will challenge the stability and texture of the emulsion so we need to add a thickener and we choose Stearic Acid
      • we discover that by adding the Allantoin we will reduce our preservation challenge and we know that the manufacturers recommended usage guidelines for Geogard Ultra are 0.75 to 2.0% and every sample formulation that the manufacturer provided in proving preservation efficacy was at 1.0% but we also found that the Aloe Vera Juice is preserved by the manufacturer and further reduces our preservation challenge...knowing all of this information we choose to start with a 0.9% usage level of Geogard Ultra
    • now let's determine the percentages of each chosen ingredient
      • let's start with the known percentages required for efficacy or stability
        • Geogard Ultra 0.9%
        • Allantoin guideline is 0.5% to 2.0%; we know that it is effective as an anti-inflammatory at 0.5% and we do not wish to market this cream as a drug or to make a label claim so we will use it at 0.5%
        • Panthenol guideline is 1.0 to 2.0% depending on what it is being used for and our purpose is its anti-inflammatory activity in skin care and it's a costly ingredient so we will use it at 1.0%
        • Stearic Acid guideline is 2.0 to 3.0% and we are using it to thicken our cream but are not including any glide or penetration enhancers and need to avoid soaping so we'll use it at 2.8%
        • Emulsifying Wax NF (E-Wax) guideline is 2.0 to 10.0% and we know that we want a cream that is about medium thickness and we are also using a thickening agent and we do not want a stiff cream which we would get at the maximum level, and we know that we don't have an emulsification challenge so we'll use it at 5.0%
        • oils / butters need to be determined based on the feel and textural influence that they will have on the cream along with known emulsification requirements..let's say that we don't want to use the HLB System so we are going to go with a 'trial and error' approach...we know that for a cream the standard rule of thumb is a 70 to 30% ratio...we know that we are already using up 7.8% of the oil phase with out emulsifiers / thickeners so we have up to 22.2% left for our oil phase...we want our Shea Butter to offer body and moisturization so we'll use it at 8.0%, leaving us up to 14.2% oils...we want our Jojoba and Apricot Kernel oils to offer emollience and glide so we'll use them at a combination of that 14.2% and we'll decide what levels of each based on label appeal...jojoba has better consumer recognition so we'll use it at 8.0% leaving us 6.2% for our Apricot Kernel oil
    • now let's determine which phase each ingredient goes into
    • now let's lay it out for easier calculating and total our ingredient to determine how much Aloe Vera Juice we will need to get to 100%
      • Water Phase
      • Aloe Vera Juice 67.6%
      • Geogard Ultra ultra 0.9%
      • Allantoin 0.5%
      • Panthenol 1.0%

      • Oil Phase
      • Shea Butter 8.0%
      • Apricot Kernel oil 6.2%
      • Jojoba Oil 8.0%
      • Stearic Acid 2.8%
      • E-Wax 5.0%
      • _____________________________
      • Totals: 2.4% in water phase ingredients
      • 30.0% in oil phase ingredients
      • = 32.4% from 100% = 67.6% Aloe Vera Juice (let's plug that into our formula)
    • now let's do the math to determine the amount of each ingredient if we are making 8 ounces (oz) don't forget that we must first convert the percentages to decimal points by moving the decimal point 2 positions to the left to reduce the numbers to 100ths
      • 67.6% Aloe Vera Juice ? 8 x 0.676 = 5.408 oz
      • 0.9% Geogard Ultra ultra - 8 x 0.009 = 0.072 oz
      • 0.5% Allantoin - 8 x 0.005 = 0.04 oz
      • 1.0% Panthenol - 8 x 0.01 = 0.08 oz
      • 8.0% Shea Butter - 8 x 0.08 = 0.64 oz
      • 6.2% Apricot Kernel oil - 8 x 0.062 = 0.496 oz
      • 8.0% Jojoba Oil - 8 x 0.08 = 0.64 oz
      • 2.8% Stearic Acid - 8 x 0.028 = 0.224 oz
      • 5.0% E-Wax - 8 x 0.05 = 0.40 oz
      • Totals 100% of ingredients 8 oz of product
    • of each ingredient to make the size batch that we'll start with let's put the ingredient, in their respective phases, into the order that may be required based on recommended usage guidelines...

      water phase adjustments...we know that the Allantoin and the Geogard Ultra must go into cold water and that the Allantoin and the Panthenol are easily dissolved in water while the Geogard Ultra takes good mixing so we'll add the Allantoin and Panthenol first without mixing and then the Geogard Ultra with mixing prior to heating
      • Water Phase
        • 5.408 oz Aloe Vera Juice 67.6%
        • 0.04 oz Allantoin 0.5%
        • 0.08 oz Panthenol 1.0%
        • 0.072 oz Geogard Ultra ultra 0.9%
    • oil phase adjustments...we know that Shea Butter requires 170F to prevent grittiness and that the melting point of all other oil phase ingredients is lower than that so we'll add it first and then add the other oil phase ingredients based on their melting points
      • Oil Phase
        • 0.64 oz Shea Butter 8.0%
        • 0.40 oz E-Wax 5.0%
        • 0.224 oz Stearic Acid 2.8%
        • 0.496 oz Apricot Kernel oil 6.2%
        • 0.64 oz Jojoba Oil 8.0%
  • To measure out the ingredients you'll want to use weight as every ingredient's usage guideline is always in weight and because you'll want to be consistent from batch to batch. Pick up a calibrated scale that goes to at least .1 grams and .001 ounces, for accurate measuring. There is nothing worse that making the perfect product and never being able to re-produce it.

    To blend your formulations you'll want to use the equipment that is appropriate to the size of the batch that is closest to the action of the equipment that you'll need to use as you progress (scale up) to larger batches. For your sample size batches, up to 32oz, the best choice is a small drink mixer, such as the Gizmo Plus by Black and Decker. For mid size batches, up to 128oz, the best choice is a small stick blender such as the Kitchen Aid or GE Immersion Blenders. For large batches, up to 3 gllns, the best choice is a small industrial Immersion Blender such as the 16Quart Immersion Blender by Waring. For large batches, above 3 gllns. but below 10 gllns. the best choice is an industrial Immersion Blender such as the 10 gallon Immersion Blender by Waring or Ryobi. Batches beyond this size will use Manufacturing Mixers offered through professional Equipment Suppliers.

    Once you have emulsified your product you can separate your test samples, for sending out to test labs and trying among your friends to determine whether, or not, it meets with your requirements. You will also want to test the pH of your product to determine whether, or not, you'll need to make an adjustment by adding an ingredient to adjust the pH based on manufacturers recommendation for efficacy or your desired activity. In this case we know that Geogard Ultra is most effective at a pH range of 3.0 to 6.0 so we'll need to test the pH, using test strips or a pH meter.
    Supply Sources:

Information Clarification
1. Manufacturers Recommended Usage Guidelines: these are established, based on a number of factors, during the manufacturers testing of that ingredient. There are ranges because there are some variables that will change based on the formulators requirements, i.e., incompatibility, combinations of ingredients that accomplish the same activity reducing the required effectiveness of each, individual, ingredient, cost control, regulator limits, the addition of ingredients that will enhance the activity and reduce the requirement and so on....i.e., if you are using Alpha Arbutin as a skin lightening ingredient you would know that the manufacturers recommended usage guideline is from 0.2 to 1.0%, you also know that this ingredient has the potential to be irritating, you also know that one of the challenges to the efficacy is absorption through the tissues so you have a great, scientific, starting point...you know that you want to keep the usage level as low as possible based on the irritation potential, you know that if you add a penetration enhancer you will reduce the requirement and be able to use less so, you would start with 0.2% and run your trials to determine how well your penetration enhancer worked and make modifications, if necessary.

2. Preservative Optimization and Establishing Shelf Life: this is where you determine the exact level of preservation necessary to prevent microbial contamination using your chosen preservative. To do this:

  • create your formula and stabilize the aesthetics, i.e., look, feel, function, performance, thickness, and fluidity, of your product. Once you have achieve what you want
    • separate 4 samples (what you'll send out for testing) and a control (what you'll keep and store per instructions), date stamp and label them all with preservative levels and send the sample to an independent lab to test for microbial presence (don't forget to make an indication on your printed formula)
    • if the sample test comes back clean then you now know that the preservative level is controlling any contamination present from the ingredients, the manufactring and the bottling of your product
    • every 6 months, or to your desired shelf life, send in another one of your original samples to test for microbial presence
    • if the sample comes back clean again then you know that the preservative level is preventing growth to at least 6 months and that is now your published expiration date
    • if the sample doesn't come back clean then you know that the preservative level is not controlling growth to 6 months and you will need to make adjustments by either; increasing the preservative level to begin the testing all over again or, eliminate questionable ingredients or, look at your manufacturing / bottling practices to see if there was an opportunity, for contamination, along the way that can be eliminated
    • for as long as the samples come back clean follow this process and you will keep extending your shelf life until you reach the point that you were targeting or the manufacturers maximum expected shelf life
    • once you reach the final test sample, and it comes back clean you may wish to reduce the preservative, since it is not a beneficial inclusion for the performance in your formulation
    • if you would like to reduce the preservative level you would just adjust the level and make another set of samples and controls, reducing the preservative by half of the difference between the level you started with and the minimum manufacturers recommendation or just go to the minimum if you were already close, i.e., if you were working with Geogard Ultra and the manufacturers recommended usage is 0.75 to 2.0% and every test that they performed was at 1.0% and proven effective so you chose to start with 1.0%, and let's say that you would like to get it to the lowest possible level for label appeal and cost...you would now reduce your usage to 0.75% and start the sampling process over...if you get to 12 months and then start to see growth then you know that you your shelf is between 6 months and 12 months and you will need to run the samples again, sending one in at 9 months to minimize the number of tests and see if that comes back clean. If so, then you can either accept 9 months as your products shelf life so that you can use the minimum amount of preservative or, make an adjustment to your preservative level or, eliminate known challenges or, modify storage measures to improve, and reduce, the preservative challenge to extend the shelf life...if you are not happy with such a short shelf life then you now know that you will have to either; split the difference and try again or just go back to the 1.0% that you have already proven was effective for your formulation....

3. The HLB System: this is a system that was developed back in the 50's to help formula developers determine how much Surface Active Agents (Surfactants) would be necessary to hold their water, or water loving ingredients, together with their oils, or oil loving ingredients because water and oil don't mix on their own, they must be manipulated to stay together, or homogenous. This system is a good starting point if you feel that you need one and would rather not learn through the trial and error. Because every oil loving ingredient has a specific behavior they were able to provide guidelines, based on that specific behavior, of how much Surfactant would be necessary to combine those oil loving ingredients with the chosen water loving ingredients. This is not a fool proof system, at this time. It was created a long time ago and there have been many changes to the ingredients, especially emulsifiers and their source materials, since it was created. That system will also not be, easily adaptable or applicable to the lactylates, or any of the other more modern and technologically advanced, emulsifiers and surfactants, or any ethoxylated emulsifiers / surfactants / ingredients as they didn't exist, in their current state, when the system was created and the science doesn't, necessarily, apply. The better method to use when working with these ingredients is the Phase Inversion Temperature (PIT) which addresses a number of factors that will effect the stability of your water and oil mixtures that were not anticipated when the HLB System was created. The PIT has a direct impact on the stability of the mixture that is independent of the level of emulsifier / surfactants to oils and water. The PIT can be determined by monitoring the temperature at which the solution will cloud (indicating and knowing the PIT of a given formulation allows the formulator to manipulate the stability based on the order of inclusion, and temperature emulsification, of ingredients. There is a HLB System PDF available in our Library for those of you who would like to use that method.

Happy Crafting!!!!

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