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The Formulation Process
(Second in a
series)
In our
first segment of this series we discussed the differences in a recipe versus a
formula. Simply put a recipe is for a given batch size while a formula can be
adapted to any size batch simply by multiplying the batch size times the
percentage that the ingredient is within the formula. This difference is easily
realized when your development work has created a successful product and you
want to scale it to the next level.
When you are
working on developing a new product it is important that you consider how you
will be making that product both in small batches and in larger batches. As a
home crafter you may only be making products for your personal use but some home
crafters are looking at this hobby as an entryway into a cottage industry of
making specialty products for sale either in their own retail store or in local
retailers. If you never intend to make larger batches then this will be no
concern for you but if you plan on making larger batches if for no reason other
than making up products for gifts then this is a concern.
When you make a
product it is necessary to use energy to mix the raw materials. This energy is
usually a combination of thermal, chemical and/or mechanical energy. Thermal
energy is heating the product. It is necessary to control the amount of heat
used to make a product. If you do not heat the product to the correct
temperature or if you heat the product to too high of a temperature, the results
will be different. Chemical energy is the interaction of the raw materials
themselves. Emulsifiers are one common type of chemical energy but there are
others. It is necessary to always accurately measure the amount of each of the
raw materials that you use to ensure product reproducibility whether you are
making the same size batch time to time or scaling the batch to larger sizes. A
scale or balance is the best method to do this. Mechanical energy is the energy
that comes from the mixer that you use in making the product. High intensity
mechanical energy also generates thermal energy so it is necessary to constantly
watch your temperature when you are mixing your product during the batching
process. The hardest energy to control as a home crafter is the mechanical
energy. If you use a big mixer when making a small batch of the product and then
later use the same mixer for a larger batch the amount of energy used in the two
batches is different if the mixer speed and time of mixing is held constant.
Therefore to use the same amount of mechanical energy in making a larger batch
it is necessary to do one or more of the following: Use a larger mixer, increase
the speed of the mixer, mix for a longer period of time. You may find a need to
have several different types of mixers for different types of products and
different batch sizes to be efficient in your manufacturing process.
The types of
products that most home crafters make include soaps, butters, shampoo,
conditioners and emulsions. Conditioners are usually emulsions and emulsions can
be classified as creams or lotions and further classified as either O/W (oil in
water) or W/O (water in oil). This last classification tells you if the emulsion
has the water as the continuous phase (O/W) or the oil is the continuous phase
(W/O). We will talk about this difference later. There are several other
classifications that can be applied to describing an emulsion.
An emulsion is
made by mixing two or more immiscible phases such that it forms a stable
product. This can be simply characterized by mixing oil and water. The terms oil
and water are generic and mean materials that are oil soluble or dispersible and
materials that are water soluble or dispersible respectively. In very simple
terms you can think of salad dressing consisting of oil and vinegar as being an
emulsion but it is very unstable since you have to shake it before use. This
simple emulsion can be stabilized by several means including high shear mixing
or adding a chemical emulsifier. Now closing the circle from my earlier
paragraph about mixing processes and scale you can see here that making a small
amount of vinegar and oil can be shaken in a cruet but if you make a 5-gallon
batch you could not shake that easily. It will be necessary to devise another
method to mix the batch so that the results will be equivalent to the cruet. The
same processes are applicable to making personal care products. The above
discussion is but one example of the need for this forward thinking during your
development process.
As a
digression, going back a little over 30 years ago when I first joined the
industry I was working for a chemist at a large cosmetics company. He had
developed a new blusher that was very process intensive. Marketing had approved
this product without knowing anything about how it was made. This blusher was
not made the same way that blushers were usually made and the process to make
this product was 100% longer than the standard. When the laboratory turned the
formula with the process instruction over to the manufacturing department there
was a lot of controversy over this product. There were many recriminations over
this and the result was that all new products had to go through a pilot process
to determine the best manufacturing procedure before technology was transferred
to the manufacturing department.
As a home
crafter you will be limited initially by using the equipment that you have
available. This is usually sufficient for making batches up to a kilo. By
convention, I will refer to all units of measure in metric terminology. For a
rough approximation, a kilo is about 1 quarts. It is 2.204 pounds. One of the
niceties of using the metric system of weights and measures is that everything
is based on 100. If you are using a formula which is written in percent (derived
from the Latin percentum, per 100) then those percents are equal to the amount
of the material needed to make 100 grams. A kilo is 1000 grams and with a
formula it is only necessary to move the decimal one place to the right to equal
1000 (100.00 1000.00 one place to the right). The equipment that you will need
will include stainless steel pots (a double boiler is good), a thermometer in
Celsius and a mixer. Here the mixer is the most important piece of equipment
because this is the limiting factor in determining your batch size. If the mixer
is very small then you will not be able to make larger batches because you
cannot adequately mix the batch. Conversely, if the mixer is very large then
making a small batch will be difficult. Many of you will use a ‘stick blender’
as your primary mixing tool. It is possible to use a ‘MixMaster’ type mixer in
conjunction with a “Waring Blendor” being used as a homogenizer. The Waring
Blendor or equivalent is an extremely versatile piece of equipment that is often
found in the laboratory for its high shear capabilities. A gram scale or balance
is also an essential piece of equipment for accurately weighing the raw
materials reproducibly. Without the scale you will be hampered by the inherent
inaccuracies and lack of fine tuning the reproducibly of your work if you have
to use volumetric measures like cups, quarts, teaspoons, etc. For the
thermometer try to use a metal dial type thermometer instead of glass. Nothing
can be more disheartening than to have your glass thermometer break in the batch
that you have been lovingly producing. Finally, most of you will be using your
kitchen stove for heating your batches. Later, if you decide to create a
‘laboratory’ for your work you will want to get a couple of hotplates to use to
heat your phases.
The last part
of this discussion is need for cleanliness. It is not necessary to have a
sterile work surface because the reality is that you cannot maintain a sterile
work surface or work area. In commercial production the area and surfaces are
not sterile but they are clean and hard surfaces are usually wiped with alcohol
or bleach prior to use to reduce bacterial counts. Sterility is only necessary
for making parenteral drugs; those which are injectable. In your work area you
only need to wipe your equipment with 70% rubbing alcohol to maintain a clean
area.
This
concludes our discussion of the equipment needed to make your own personal care
products in your home and in the next edition of the newsletter I will begin to
discuss raw materials used in specific types of products. I will start with a
discussion of emulsions. In the meantime I have an open chat available twice
weekly on Tuesdays beginning at 5PM Eastern time and again on Thursdays
beginning at 5PM Mountain time. Just go to www.thepersonalformulator.com and
look for the link on the right side of the page after you enter the site.
The
Formulator
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