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Homemade 5% Lactic Acid Facial Serum

Updated: May 13, 2022

In the last post we made a 5% fruit acid facial serum. Now it's time to make a stronger AHA serum and this is with 5% Lactic Acid. We have already made a 5% Lactic acid face toner in the past, so now it's time to make it into a serum Let's do this!


Before we begin, I do recommend watching my videos (or reading my posts) over AHAs, over Serums, and my video on how to raise and lower ph levels before reading this post. It can be a bit confusing working with lactic acid because it is a very strong acid that brings your formulations ph down very low, so we have to buff the ph with a 10% lye solution. So that is why it is so important to watch my video (or read my post) on how to raise and lower ph levels.

Here is my Formula;

65.4% Distilled Water (can substitute with hydrosol or aloe vera liquid)

20% Aloe Vera Liquid (can substitute with distilled water or hydrosol)

4% 1,3 propanedial (can substitute with vegetable glycerin)

4% Leucidal SF Complete (can substitute with a water soluble broad spectrum preservative active in ph's between 3-4)


Okay, so your first question may be "why are you using 5.6% lactic acid when you said this is a 5% lactic acid serum" Well the reason why is because the lactic acid I am using is a 88% concentration of lactic acid, meaning 12% of it is water. That means I can't just use 5% of it and call this serum a 5% lactic acid serum. I have to figure out what percent would make it 5% lactic acid, and that came out to 5.6%. So now that we have gotten that cleared up, let's move on to the directions. I am going to be making .5 ounces of this serum.


Directions;

I used a digital scale that weighs to 0.01 grams and I used a 50 ml glass beaker to weigh everything out in. I began by adding in only 6.81 grams of distilled water. In total the formula calls for 9.81 grams of distilled water, but we need to leave some space for our buffer solution, so this is why I left out 3 grams of the distilled water, for now. Next I added in 3 grams of aloe vera liquid, and then .6 grams of 1,3 propanedial. Now it's time to add in the lactic acid. I am adding in .85 grams of lactic acid. Once it is added in it lowers the ph of your formula, mine was lowered to 2.97. The ideal ph for AHA products is 3.5-4 so we need to use a buffer solution to raise the ph. As most of us know we use citric acid to lower ph levels, but to raise the ph level we need to use a 10% diluted lye solution. If you want to know how to make a 10% diluted lye solution, check out my video (or patreon post) on how to raise and lower ph levels. So this is exactly why I left 3 grams of the distilled water out, to keep room for the buffer solution because it is hard to determine exactly how much we will need.

Before you add in your buffer solution take the ph of your formulation using a ph meter. I don't recommend ph strips when working with AHAs because ph strips just aren't very accurate and having the proper ph level really matters when formulating with AHAs. So begin by taking your ph, then add in about 5 drops of your lye solution and be sure you weigh how much of the buffer solution you add in. Mine weighed .22 grams (it's okay if your weight of 5 drops is different than mine) Then mix everything together and wait about a minute before taking the ph again. Mine raised to 3.38 with only 5 drops (yours may be different, that's okay) I then added 5 more drops, which weighed .11 grams, mixed it all together, let it sit for a minute, then take the ph again. So now the ph is 3.62, which is perfect! Again, yours may be different, as long as it's in between 3.5-4 you are okay. So now it is time to figure out how much more distilled water needs to be added. (Remember we left 3 grams out to keep space for the buffer solution.) Since we only used a total of .33 grams for the buffer solution we just need to add .33 with 6.81 (the amount of distilled water we already added) this equals 7.14. Now subtract 7.14 from 9.81 (the total amount of distilled water needed for this formula) this equals 2.67. So add in 2.67 grams of distilled water. (I told you this may be confusing, I hope it makes sense)


Now that the ph is balanced it is time to add in our preservative. Make sure you add this in last. If you add in your preservative before you add the lactic acid it could possibly deactivate your preservative since most preservatives aren't active in low ph levels. So be sure whatever preservative you are using is active in ph's between 3-4. I am using Leucidal sf complete which is active in ph's between 3-8. I added in .6 grams of the leucidal sf complete. I then mixed everything together and took the ph one last time. Keep in mind your preservative may raise your ph a little. My preservative raised mine to 3.74 but it is still in between 3.5-4 so we are totally good! Now it is time to add our gelling ingredient. I am using hyaluronic acid that is 1-1.5 million daltons. You could use sepimax zen or siligel. I added in .15 grams of hyaluronic acid and let it sit for 3 hours. After 3 hours come back give your product a really good mix and bam! Now everything is gelled! I package my serum in a .5 ounce glass dropper bottle and added on a label.


If you aren't familiar with serums or Alpha hydroxy acids I recommend watching my video over serums and my other video over alpha hydroxy acids (or you can read the posts here on patreon) but when using a serum you want to begin by washing your face, then using a toner (if you normally use one in your skin routine) then while your face is still damp take 2-3 drops of the serum and massage it into the skin, including your neck. Let it sit until it dries, then follow with your usual moisturizer. Also when using an alpha hydroxy acid you want to make sure you are always protecting your skin from the sun with a sun screen as alpha hydroxy acids make your skin very sensitive to the sun for up to 7 days after use.

Hope you all enjoyed this recipe! Here is the exact recipe I used.


Distilled Water - 9.48 grams

Lactic Acid - .85 grams

10% lye diluted buffer solution - .33 grams



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