Hi! I am making a scalp tonic, and need a preservative that is propylene glycol free as it irritates my scalp. I would appreciate any input as I do not know much about formulating. I was going to use Leucidal Sf, but I have read that it may not be really effective. I would like to keep it as "natural" as possible, but understand that safety of using it is equally important. Also if this helps, I had some Ph strips in house that were 4.5- 9, and it did not change the color on it so I am assuming it is pH 4.5 and under.
Formula so far
1 ml essential oils
1 ml polysorbate 20
120 ml (4 oz) distilled water
Thank you in advance for any help!