Members Directory - Chemists Corner

Dtdang

Member

August 10, 2018 at 2:10 am in reply to: Ingredients to remove dark spots and even skin tone

Thanks ngarayeva001!

Dtdang

Member

August 10, 2018 at 2:09 am in reply to: Which Co-Emulsifiers work well with Stearic Acid (Emulsifier)

Thanks ngarayeva001! After trying different % wt, I got stable creams, but they had soaping effect. Plan to add silicones. I do have glycerin & aloe vera on water phase.
I plan to change mango butter and coconut with others. Do you have any suggestions?

Dtdang

Member

August 8, 2018 at 1:24 pm in reply to: Whitening Cream too thick and not spreadable

I find that to dilute weak acid to control concentration and pH are most effective way. Irritating is from pH too low. Do you measure pHon your final product?

Dtdang

Member

August 8, 2018 at 1:17 pm in reply to: To get rich and shiny look to night cream

Send me a piece

Dtdang

Member

August 7, 2018 at 9:14 pm in reply to: Is there anything I can do to make this product actually effective on my skin?

For example, for reduce pH, we usual add TEA or Na0H. Do not do that.
dilute the AHA or BHA to near desired pH

Dtdang

Member

August 7, 2018 at 9:11 pm in reply to: Is there anything I can do to make this product actually effective on my skin?

I just new in cosmetics
but selecting the ingredients which have molecular small comparing the pores.
Go with natural. Minimize adding additional ingredients that are not benefit for skin.

Dtdang

Member

August 7, 2018 at 1:17 pm in reply to: Cetyl alcohol

Try changing emulsifier
emulsipure green coffee or creamMaker green coffee

Dtdang

Member

August 6, 2018 at 2:41 am in reply to: Which one is good to replace Triethanolamine? Its smell ammonia

Thanks Belassi

Dtdang

Member

August 6, 2018 at 2:15 am in reply to: Which one is good to replace Triethanolamine? Its smell ammonia

Dear Belassi!
Can I dilute 70% glycolic acid because I need the concentration less than 10% and the final pH must be equal or greater than 3.5. This way I do not need the adjuster.
For example, I measure 13 mL of 70% glycolic acid and add into it with 39 mL of distilled water. This way I can have 8.75% glycolic acid.
The pH can be calculated as below:
[H+] = square root of (Ka x M(final in mol))
pH = -log[H+]

Please give me your comments. Thanks a lot.

Dtdang

Member

August 5, 2018 at 5:45 pm in reply to: Which one is good to replace Triethanolamine? Its smell ammonia

Thanks all for helping me learning!
I think about basic concept diluting weak acid with water and measure the final pH when taking chemistry a long time ago. If this works, I do not need adjuster. My concern is the accuracy of concept Vs. practice.
For glycolic acid, the pKa = 3.83, I want to keep pH = 4, then about 50% free acid will be absorbed to skin.
Is it correct for real practice?

Dtdang

Member

August 5, 2018 at 3:50 am in reply to: Which one is good to replace Triethanolamine? Its smell ammonia

Thanks Belassi.

Chemist77! what do you mean situ? I do not get it. Thanks

Dtdang

Member

August 5, 2018 at 12:21 am in reply to: Which one is good to replace Triethanolamine? Its smell ammonia

The main reason is for pH adjuster

Dtdang

Member

August 2, 2018 at 12:36 pm in reply to: Ingredients to remove dark spots and even skin tone

Thanks for all your help!

Dtdang

Member

August 2, 2018 at 4:42 am in reply to: Ingredients to remove dark spots and even skin tone

Dear Belassi!
Thanks a lot! please name the silicones. I am new in this area. I will try it.

Thanks

Dtdang

Member

August 2, 2018 at 4:38 am in reply to: Ingredients to remove dark spots and even skin tone

Thanks amitvedakar! I will try it

Dtdang

Member

August 2, 2018 at 3:35 am in reply to: How to dissolve Salicylic acid or AHA acid in oil?

AHA and BHA acids: Look at pKa value for selected acid. The pH = pKa, it’s 50/50: 50% free acid and 50% ionized. The free acid will absorbed through skin. The ionized acids will not absorbed through skin. But, the portion of ionized acids on the skin will become free acid. Then, it absorbed through skin, very slowly.
For AHA, the best performance is pH=4 with concentration less than 10% .
For BHA, the best performance is pH=3.5 with concentration 1 - 2%

To calculate the weight required for AHA/BHA:
I use c1v1 = c2v2

Dtdang

Member

August 1, 2018 at 11:45 pm in reply to: Ingredients to remove dark spots and even skin tone

Dear Dr.
My oil phase that includes emulsifier ( creamMaker green coffee), coconut oil mango butter, cetyl alcohol and vitamins e is only 18.2%. But lotion has soaping effects
How can I eliminate the soaping effect? There is any guideline about soaping effect?

Dtdang

Member

August 1, 2018 at 11:39 pm in reply to: Ingredients to remove dark spots and even skin tone

Dear Dr.
FDA requires glycolic acid: concentration is less than 10% and the final pH >3.5
my concern is that what pH and concentration make glycolic acid most active (effect)?

Dtdang

Member

August 1, 2018 at 3:15 pm in reply to: Ingredients to remove dark spots and even skin tone

For AHA: glycolic or lactic acid, which one is better for fading dark spots?
On internet, it said, glycolic acid just removes only dead skin cells.
But, can not expose to sun, during 7 days after stop using glycolic

Anyone have experiences on AHA? Thanks in advance!