# Advice on diluting or combining 2 chemical peel acids together ?

Member
edited December 2019
Hi, If I have a teaspoon of  40% AHA(LACTIC ACID) and teaspoon of 10% BHA(SALICYLIC ACID) will combining them result in a 20% AHA and a 5%BHA solution, I know it sounds straight forward but it’s not with water but another acid so I had to make sure, and would there be anything else to beware of?
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Think of it this way.  40% solution means the following:  A *5 gram sample will contain:

1.  2 grams of Lactic Acid
2.  3 grams of water

Similarly, a 10% solution of BHA will have the following:

1.  1 gram of BHA
2.  4 grams of water

So, if you combine both solutions, you would get the following...

1.  2 grams of lactic acid
2.  1 gram of BHA
3.  7 grams of water

That would be 20% lactic acid, 5% BHA.  Now, if you poured that sample into something else you are going to change the percentages.

*incidentally, a teaspoon equals about 5 grams.
• Member, PCF student
Developing a chemical peel formula is generally considered to be quite an advanced formulation project for a cosmetic chemist. There are also regulations that you need to be aware of when working with AHAs.

Please make sure you have the relevant experience before attempting this project. Your suggestion of using teaspoons suggests that you do not have this experience. Cosmetic chemists work in weights with percentages.

I am not trying to deter you from creating your own products just trying to make sure you do it safely.
@ozgirl - I agree completely

• Member
Perry said:
Think of it this way.  40% solution means the following:  A *5 gram sample will contain:

1.  2 grams of Lactic Acid
2.  3 grams of water

Similarly, a 10% solution of BHA will have the following:

1.  1 gram of BHA
2.  4 grams of water

So, if you combine both solutions, you would get the following...

1.  2 grams of lactic acid
2.  1 gram of BHA
3.  7 grams of water

That would be 20% lactic acid, 5% BHA.  Now, if you poured that sample into something else you are going to change the percentages.

*incidentally, a teaspoon equals about 5 grams.
Thank you this is really helpful. Why is 10% solution of BHA, 1gram? I would have thought 10% of 5grams is 0.5grams?
• Member
edited December 2019
ozgirl said:
Developing a chemical peel formula is generally considered to be quite an advanced formulation project for a cosmetic chemist. There are also regulations that you need to be aware of when working with AHAs.

Please make sure you have the relevant experience before attempting this project. Your suggestion of using teaspoons suggests that you do not have this experience. Cosmetic chemists work in weights with percentages.

I am not trying to deter you from creating your own products just trying to make sure you do it safely.
Thank you for not trying to deter me and your concern for my safety. I will do a patch test to see if I don’t have any adverse reactions. Perry explained very to me the answer to my simple question, this is for my personal use I’m not trying to sell anything, if there is anything else you’d like to share which doesn’t come with a price please do.I know how to work metric, percentages and imperial measurements interchangeably without any issues. This isn’t rocket science.

Thank you again for your concern.

@Bluewoodg - Yes, 0.5 g would be correct.  I made a mental math error.

Corrected...

A 10% solution of BHA will have the following:

1.  0.5 gram of BHA
2.  4.5 grams of water