30% Salicylic Acid Peel - Crystals??

Formulating

30% Salicylic Acid Peel - Crystals??

Posted by mflick1 on February 27, 2014 at 4:01 pm

Hello All,

Hope someone can offer some help on this. I made a 30% Salicylic Acid Peel solution (I made about six bottles, 120 ml ea) and the next day there were crystals at the bottom that formed. What could have caused these crystals.

I added the Salicylic Acid, powder form, in SDA 40, added a little heat until acid dissolved and then added NaOH to adjust pH.

Any advise?

Also, if I made this un-buffered and did not use NaOH to adjust pH, maybe I could avoid this next time?

Thank you!

DavidW replied 10 years, 8 months ago 5 Members · 7 Replies
7 Replies

mikebavington

Member
February 27, 2014 at 5:24 pm

Is 30% salicyclic acid permitted in cosmetics products that arent intended to be diluted?
chemicalmatt

Member
February 27, 2014 at 5:58 pm

Can anyone say “supersaturation”? Your product, settled, cooled crystallized. This is Physical Chemistry 101. You’ll need a co-solvent, dude. I advise ethoxtdiglycol or propylene glycol. Check the Merck Index for solubitlity parameters.
mflick1

Member
February 27, 2014 at 6:45 pm

Hummm…. Well I first wanted to make this un-buffered but guess I did my initial math incorrect since my pH wasn’t as close as I wanted it to be. So how do you explain other manufactures out their who make un-buffered solutions which is just the Salicylic Acid and ethanol? You don’t HAVE to have buffers.

I’ll guess I keep playing with it….. Also, I did think of supersaturation, again, guess my math was off, I’ll have to go back and review

O and yes chemical peels are permitted…
Bill_Toge

Member
February 27, 2014 at 7:27 pm

@mikebavington not in Europe, the limit is 3% in rinse-off hair products and 2% in everything else
mikebavington

Member
February 27, 2014 at 7:43 pm

I know peels are permitted, but I think 30% might be against your country’s regulations. Where do you live?
mflick1

Member
February 27, 2014 at 7:53 pm

I’m in the US, we are a physicians only line. I’ve been in regulatory and compliance for many years so I’m not concerned with that. I’m switching to R&D and I’ve been working under our chemist while trying to earn my second degree in science but she is out on vacation for two weeks, hence the help on this issue.
DavidW

Member
February 28, 2014 at 10:14 pm

What Chemicalmatt said. You need other solubilizers. As a manufacturer I have customers asking me for all sorts of crazy peels lately including high Sal. Acid

30% Salicylic Acid Peel - Crystals??

mikebavington

chemicalmatt

mflick1

Bill_Toge

mikebavington

mflick1

DavidW