Urea farnesol xylitol

Urea, Xylitol, Farnesol Lotion
-------------------------------

===============
=   FORMULA   =
===============

Purified Water				52.25%
Xylitol					5.00%
Xanthan					0.30%
Glycerin				2.00%
Propylene Glycol			5.00%
Petrolatum				10.00%
Mineral oil				2.00%
MCT Oil					3.00%
Cetearyl				1.00%
Emulsifier				3.00%
Stearic acid				1.00%
Citric acid				0.23%
Farnesol				0.20%
Urea					8.00%
Lactic acid				0.00% (to pH 5.5)
Sodium citrate				1.10%
Dimethicone				1.00%
Sodium Lactate 60%			4.17%
Preservative				0.75%

===============
=  EQUIPMENT  =
===============

Lab mixer or stick blender
Scales:
	Accurate to a gram or lower and capable of multiple kilograms
	Accurate to a tenth of a gram or lower and capable of up to a kilogram
Hot plate or stove [1]
One or two instant read thermometers with Celsius scale
Measuring spoons
Small whisk [2]
Product containers [3]
If using a regular hotplate or stove you will need a large heavy bottomed pot with medium high walls
Glassware:
	1x very large (2L+) glass bowl
	2x large (1L) pyrex beakers or pyrex measuring cups
	4x medium (250mL) pyrex beakers
	4x small (100mL) pyrex beakers [4]
2x LDPE wash bottles (500mL)  [5]
	1x filled with deionized or distilled water
	1x filled with 91% isopropyl
Coffee grinder or mortar and pestle
Metal mesh that fits over a piece of your glassware
pH meter
RO-DI filter or Zero-water filter (not Brita or any other) or a store of distilled or deionized water [6]
Timer
Calculator

===============
= CONSUMABLES =
===============

Ready-to-use oil-in-water non-ionic emulsifier [7]
Ready-to-use broad spectrum preservative [8]
Citric acid – chelator, buffer
Xylitol [9] – humectant and biofilm disruptor
Urea (prills) [10] – too many benefits to list
Stearic acid – thickener
Sodium lactate – humectant, buffer
Isopropyl alcohol
Disposable pipettes
Cetearyl alcohol – thickener and texture enhancer
MCT oil – aka caprylic/capric triglycerides
Mineral oil – the staple lotion ingredient
Petrolatum – the staple lotion ingredient
Glycerin – humectant
Propylene glycol – humectant, water activity reducer
Xanthan gum – binder, structure provider
Lactic acid – active skin benefit, pH adjuster, buffer
Dimethicone – adds slip, active skin benefit
Farnesol – deodorizer, biofilm disruptor


[1] Ideally you want a hot plate that can sustain a steady temperature below 100C. Consumer electric burners are only able to be on at full power or off entirely which is not going to ever let you keep a steady temperature below boiling. The key to finding a hot plate which is capable of this is to find a laboratory hot plate. You can find them used very cheap, look for a  well known brand.

[2] A better option to using a whisk is to use a magnetic stirrer. Again, they can be found used for cheap – don't bother with the cheap new no-names. Make sure to get a few appropriately sized teflon stir bars.

[3] I highly recommend getting airless pump bottles. The largest commonly available ones are about 100mL to 125mL. The advantage to the airless pump is that when dispensing they don't leave an air gap on top of the product – if there is a  gap then in order to dispense product air must be sucked in from outside (otherwise the bottle would implode). Airless pumps have a piston on the bottom that moves up when the product dispenses.

[4] You can substitute small plastic jello cups (not sure what they are called, they are a little container with a removable top and are disposable. These are useful to have even if you have all the glassware.

[5] A wash bottle is squeezable and has a spout that points down from or perpendicular to the opening connected to a tube that travels the length of the bottle.

[6] Zero-water filters contain mixed-bed deionizing resin which will provide you with a way to turn tap water into deionized water on demand.

[7] Emulsifying wax NF, Glyceryl Stearate & PEG-100 Stearate, Polawax are good choices.

[8] Germaben II, Phenonip are my go-tos.

[9] Be aware that xylitol is very sweet and extremely toxic to dogs. If you have a dog, keep it away from them.

[10] You will need to crush or grind the prills and sift the powder through metal mesh. Do this ahead of time.

============
= PROCESS  =
============

The first thing that needs to be done is washing the glass, implements and product containers and setting up the production area. To clean these items you want to wash with a detergent, rinse thoroughly with tap water, then use the wash bottle of deionized water to rinse again, then rinse using the wash bottle of isopropyl, then place on a rack to dry.

Have a print out or a written copy of the formula on a clipboard with a pen handy. Underline or highlight the weights and percentages. Make sure the weights have been computed including the water amount. Add the weights of the farnesol, dimethicone, and preservative and put that number on the paper and put a circle around it.

Have all ingredients out and ready to access. Have paper towels and dispensing tools handy and easily grabbable. Have a calculator nearby.

Place your scales in a flat, out of the way area. Weigh the large (2L+) glass bowl and write the weight with a sharpie on the side of the bowl – this will easily come off with isopropyl, don't worry.

Place a large beaker on the scale and tare (zero) it – after adding each ingredient you are going to tare the scale again so you don't have to add the numbers each time. Add petrolatum ( you can scrape it on the side if you like, it will turn into liquid and flow down when it heats up) until weight is reached and tare the scale (remember to do this every ingredient addition). Add MCT oil.  Add mineral oil (at this point if you are over or under by a small amount make up for it with the mineral oil). Add the cetearyl, then stearic, then emulsifier (over or under a small amount, make up for it with the emulsifier). Don't bother stirring.

If using a stove or a regular hot plate, fill the heavy bottomed pan about ¼ full with tap water and set it on med heat, when the water starts bubbling turn it down until it stops. Place the beaker with the oils in it in the water and put a thermometer in it. If using a lab hot plate, set temp to medium and place the beaker on it.

Put the other large beaker on the scale and tare it. Add 75% of the water needed for the entire product in the beaker (remember to use deionized water). Place the beaker in the water bath or on the lab hot plate.

Put a medium sized beaker on the scale and add the glycerin, remove it. Place a small beaker on the scale and add the xanthan gum. Whisking: Now very gradually add bits of xanthan to the glycerin while whisking until all the xanthan is incorporated, put the xanthan+glycerin beaker on the scale, tare it and add the propylene glycol, then whisk thoroughly and set aside. Magnetic stirrer: do glycerin and then do propylene glycol, place on stirrer and set to medium speed, then slowly drop in the xanthan until mixed and set aside.

Put a medium beaker on the scale and tare it, then fill with the xylitol. Whisking: add xylitol to water beaker sitting in the water bath while whisking until mixed, then add xanthan+glycerin+propylene glycol and whisk until mixed. Magnetic stirrer: remove water beaker from water bath and place on stirrer, set on medium stir and add xylitol, wait until mixed, then add xanthan+glycerin+propylene glycol, wait until mixed, place back in water bath.

Weigh the citric acid and sodium citrate and sodium lactate and add to the water beaker.

Monitor the temp of the oil beaker and the water beaker. You will need to lift the thermometer so that it is not touching the vessel to get a proper reading of the liquid. When they reach 70C set a timer for 10 minutes. Make sure the temp does not drop below 70C during this time. You will probably need to monitor the water level in the pot and add water to it if needed. It is helpful to have an electric tea kettle running on the side so you can add already boiling water and not have to cool down the whole pot every time water is added.

----------------------------------
Aside: why 70C for 10 minutes?

Technically, all we need to do to get a good emulsion is bring the water and oil phases to the same temperature and mix them, so 		why hold at 70C? Well, boiling water is a good way to kill the microbes in it but there is nothing magical about 100C that kills microbes – if we get it up to 70C and leave it there for a while it will be almost as effective as boiling it, and it won't cause nearly as much harm to the ingredients.
----------------------------------

While the two beakers are reaching temp, weigh out the urea and set aside.

Weigh in one container using the smallest scale the dimethicone, the preservative, and the farnesol, adding an extra 10% of each, mix and set aside.

When the timer goes off, pour the water beaker contents into the large bowl, place the blender in it and turn it on low, then dump the oils in and let it run, blending everything together. DO NOT LIFT UP AND LOWER THE BLENDER WHILE MIXING, this will incorporate air into the product. You do not want to let the mixer blade to ever come into contact with air while spinning, nor do you want the product moving up and down over the blade while mixing. Just keep it in one place and the vortex caused by the blade will move all the liquid around by itself.

pH adjustment:

When mixed use the pH meter to check the pH. Target pH is 5.5 - 6, so monitor pH while adding small amounts of lactic acid. Note that even if the product is in the target pH range without adding the acid, we still want to add some to create the buffer. However we do not want to go below 5.5 if we can help it, so if it stabilizes anywhere in range after adding the lactic acid you should call it good enough.

----------------------------------
Aside: how does urea degrade and how do we stabilize it?

Urea will degrade in the presence of (1) heat, (2) air, (3) water, and (4) basic pH. If we can keep our product in contact with the minimum amounts of those as possible we will be able to achieve a high level of stability. This formula is designed to do this in four ways: (1) urea is added as late into the process as possible to minimize its exposure to high temperatures, (2) the product is ideally dispensed using airless pump bottles, (3) the use of propylene glycol and other humectants lowers the water content, and (4) a dual buffer system keeps the pH acidic.
----------------------------------

Next, add the urea and mix.

Tare the scale and put the vessel on it and compute the amount of water you need to add to the product to reach the desired ending weight using this formula:

SCALE_WEIGHT - MARKED_WEIGHT = X
DESIRED_END_WEIGHT - X = Y
Y - CIRCLED_NUMBER = AMOUNT_WATER_TO_ADD

----------------------------------
Formula explained:

X is the amount of product in the vessel; since you weighed the empty vessel earlier and marked it then subtracting that from the vessel with the product in it gives you the product weight which is X. When you subtract the desired end weight which is 100% of all the ingredients from X, then you get the amount missing which is Y. You don't want to forget the remaining ingredients left, so take the circled number you put on the sheet when you added the weights of the farnesol, dimethicone, and preservative and subtract that to get the amount of water to add.
----------------------------------

With the vessel on the scale and having computed the amount of water to add, tare the scale again and add deionized water until you get to the computed number.

Take it off the scale and mix it. When mixed add the farnesol, dimethicone, and preservative mix slowly while mixing. Try to get it all out by pouring, then spray a bit of deionized water from the wash bottle in it to get some more out, but remember we added 10% extra of each of those so anything left over in the glass after that can be ignored.

Keep mixing it. If it starts getting thick it is time to dispense. If it remains liquid then as long as you have mixed for at least two minutes you can dispense.

Pour the product into the containers. If you are using airless pumps, you will want to fill as much to the top as possible while leaving room for the tube coming down from the pump to fit. You don't want to spill over so do one and screw the pump on to see how much to leave at the top, then fill the rest of the containers until you run out of product and then cap them. About 100g of product is about 100mL of volume, and plan to make about ½ of a container extra for the batch. This stuff is cheap and making it isn't that hard, but it is still a pain in the ass, so don't skimp on it.

Well, now you get to clean up. Here is a tip – use that electric kettle to boil some more water and use that to clean the bowl and the blender.

In a week check your product with the pH meter by dispensing some in a beaker and mixing it up to 50% with warm deionized water. If it is below 4.5 or above 6.5, something is wrong and you need to figure out what before you keep using that batch.

Check again in another few days and then every week for a few weeks and then every month until that batch is done. If you are consistently making stable batches you can skip the regular post-production pH checks but you still want to check each batch in its mid-lifetime at least once to make sure something hasn't gone horribly wrong.

It isn't guaranteed that a problem will make the pH change a lot, but if the pH does change a lot then it is guaranteed that there is a problem.

===========
=   FAQ   =
===========

How do I use this guide?

Read the entire thing including the notes, then decide if you want to do it, then decide if you can do it, then follow it.

What is this and why is this?

I need something that is:
a highly effective moisturizer
available in large quantities
antimicrobial with regard to common pathogenic skin flora
benign or beneficial to the normal skin biome
not expensive

To my knowledge a product with these properties does not exist. My natural tendency is to look for practical solutions to problems, and without a ready solution then that requires doing it myself, so long as I can be sure that I am able to do it safely and within the parameters of my own competence.

What is urea?

Urea is a well known humectant, and one of the most effective moisturizing agents. Additionally, urea functions as a keratolytic agent, which causes skin to shed its outer layers and soften. It also possesses many other beneficial skin properties. Unfortunately the tendency of urea to cause mild irritation in people during initial use causes it to be omitted from or minimized in most moisturizers.

What is xylitol?

Xylitol is a naturally occurring sugar alcohol found in various fruits and vegetables. Over the past decade it has become a star player in dental hygiene, as it has been found to actively prevent dental caries. Along with its known humectant properties, multiple studies have shown that it is also effective in suppressing the growth of pathogenic bacteria on the skin. A notable property is the disruption of biofilm formation in Staphylococcus aureus, while leaving Staphylococcus epidermidis unaffected.[A]

A word of warning: xylitol is highly toxic to canines. If you have a dog, keep them away from anything containing xylitol!

What is farnesol?

Farnesol is a natural sesquiterpene alcohol found in various essential oils. It has been used for decades as a deodorizer and an ingredient in perfumes, but has recently become the object of study with regard to skincare. It has been found to be antimicrobial, specifically targeting pathogenic strains of fungus and bacteria. It suppresses germ tube formation in Candida albicans and disrupts the formation of biofilm in Staphylococcus aureus, while leaving Staphylococcus epidermidis unaffected.[A]


Why use mineral oil and petrolatum?

All of the ingredients used in this formula are fine for skin. There is a lot of superstition and unscientific belief around skincare, and one of those beliefs is that petroleum originated occlusives are pore clogging or that they cause an allergic reaction. I am not saying that it is impossible that those are true, but it is unlikely.[B][C]

=============
=  SOURCES  =
=============

[A] "Xylitol and farnesol have potential for controlling the skin-microfloral balance because of their selective effects and inhibition of biofilm formation." Katsuyama M, Ichikawa H, Ogawa S, Ikezawa Z. A novel method to control the balance of skin microflora. Part 1. Attack on biofilm of Staphylococcus aureus without antibiotics. J Dermatol Sci. 2005 Jun;38(3):197-205. doi: 10.1016/j.jdermsci.2005.01.006. Epub 2005 Mar 2. Erratum in: J Dermatol Sci. 2005 Sep;39(3):196. Masako, Katsuyama [corrected to Katsuyama, Masako]; Hideyuki, Ichikawa [corrected to Ichikawa, Hideyuki]; Shigeyuki, Ogawa [corrected to Ogawa, Shigeyuki]; Zenro, Ikezawa [corrected to Ikezawa, Zenro]. PMID: 15927813.
[B] "based on the animal and human data reported, along with the AAD recommendation, it would appear reasonable to conclude that mineral oil is noncomedogenic in humans." DiNardo JC. Is mineral oil comedogenic? J Cosmet Dermatol. 2005 Jan;4(1):2-3. doi: 10.1111/j.1473-2165.2005.00150.x. PMID: 17134413.I
[C] "Only a few cases of allergic contact dermatitis to white petrolatum have been reported." Kang H, Choi J, Lee AY. Allergic contact dermatitis to white petrolatum. J Dermatol. 2004 May;31(5):428-30. doi: 10.1111/j.1346-8138.2004.tb00698.x. PMID: 15187314.