The order of your pH dependent products

as I don't use any retinoids

Click image to view: What's In My Skincare Wardrobe: Actives (Prescriptions, Antioxidants, and Acids) Edition

at night because it makes your skin photosensitive

if there was a reason for that specific order

was the wait time necessary

and if they all function at a low pH, can't they just apply them one after the other?

Borderline NSFW analogies if the technical terms are making your head spin

The reason for the order has to do with the relative pH requirements of the different products. Vit C and the other acids need to be at different pHs to be effective. Think of it as cooking temperature- different meats require different temperatures, right? So say that you are cooking beef and pork to medium-rare.

If you cook them both together at the same temp, you are going to get into trouble - beef needs a temp of 130-135 but pork needs a temp of 145-150. So if you cook them at the 'beef temp', the pork will be undercooked, but if you cook them at the 'pork temp' the beef will be waaay overcooked. So you have to do them separately. Does that make sense?



Also, your Hada Labo is hydrating so it will contain moisturizing ingredients that will block the acids' ability to access the skin. It should go after all your acids.

Start with the lowest pH dependent product, which is the Vit C. It needs to go on a 'bare' face, and it's so low-pH-dependent [link] that you either have to wait 15-20 min after washing your face for your skin to naturally go back down to pH 4.2-5.6 on its own [link], or force it down with a pH adjusting toner (I use Mizon AHA BHA toner, which is around 4.5, so on the low end of 'natural' skin pH) if your skin will dry out too much for waiting.

The harder your Vit C has to work to get your skin to a sub-3.5 pH, the more wasted effort- when the Vit C could have been working its magic on your skin, instead it's burning its efforts on lowering pH. Vit C needs 15 minutes ~alone in a candlelit room with smooth jazz~ with your skin (and by that I mean Vit C has a 15 min absorption time/effectiveness window), and if it's gotta waste time pleading at the door for you to lower that pH and let it in baby! Then that's minutes of antioxidant sexytime that you are giving up.

However, BHA has a higher pH effectiveness range, of 3-4, so you really don't want it crashing your Vit C party. AHA is higher still, all the way up to 4.5. So since your Vit C is ~sensitive~ you want to take care of it before you start flirting with higher pH products like BHA and AHA, because it will get huffy and sulk off.

The reason you want BHA before AHA is less about pH (unless your AHA is between 4-4.5 in which case it's going to mess up your BHA) and more about oil. BHA is oil-soluble, AHA is not. So, you need the BHA to go in first and battle the sebum in your pores and clear them out, so it's not in the way when you apply your AHA.

Some last notes and warnings





**If you are 'purging' from a product that doesn't contain actives in the concentration %pH needed to be 'active', it ain't purging. Flee., including all those 'first' essences. So if your product says to use it immediately after basic cleansing and before any other products, and you use actives, ignore those instructions and use themthe actives.In fact,, if that makes it easier, because they are often prepping your skin to make your skincare more effective/absorb better. (I actually sometimes 'cleanse' my skin after my actives are done, by swiping with my Mizon AHA BHA toner on a cotton square to remove any residue, and dirt, sebum, or dead skin that the acids dissolved off my skin. I want that slurry of goo off my face before I start moisturizing, ugh!)(meaning that they need your skin to stay at a specific pH while they work)You may have heard that Vitamin C should not be combined with niacinamide, or that it doesn't matter, that the pH doesn't matter, or that the pH matters, that you can layer things on top of one another, that you have to wait 20 min between everything, and other contradictory statements. It really depends on which form of Vitamin C you are using (LAA is both pH dependent and also should not be combined with niacinamide, so best to wait 30 min in between using those two), and what is the pH range of your specific products.So why that specific order?Most common actives require a 15-20 minute absorption/activation window in the right pH for that product, and in the event that you include multiple actives in a single routine, you'll want to follow anFor people who use LAA-based Vitamin C serums (which are pH dependent), that will usally be. (For how to incorporate retinol into an Asian skincare routine, I recommend you check out skinandtonics.com . (I do now! You can.)Pictured in order on bottom row: pH adjusting toner > Vitamin C serum > BHA > AHA > non-exfoliating acid treatmentYouuse all 3 in a single routine, but 1. that's a lot of waiting in between them, and 2. that's a lot of exfoliation in one go. Even though Vitamin C isn't technically an exfoliant, since it's a low pH and it's an acid, it may be too much for your skin if you are also using acid exfoliants. I personally use Vitamin C in the AM and BHA and AHA in the PM, which is a lot, but I also pay close attention to my skin and skip any of the above if I feel like I need to step it down a bit. Many people use only 1 or 2 out of the 3 daily, or on alternate days.I also use AHAAHA makes you photosensitive, period. AHA directions often say to use it at night, but it's actually no safer to use it at night vs the day, as studies have shown that a 10%I have not seen any studies measuring lower concentrations of AHA, but the one I use is 8% and I can't imagine a 2% difference is magically mitigating the sustained photosensitivity effect. Conclusion? You're going to need sunscreen no matter what time of day you apply it, which was my original stance even before I learned this new info.I slather on high SPF/PAduring the day if I go out.I received this question from someone about the order of Vitamin C, BHA, and AHA, because I had advised to use them in that exact order, with a 20 minute wait time in between them.They asked:They also mentioned they cleanse, then use the Hada Labo toner I linked above, then an AHA, waiting 1-2 minutes, then an LAA Vitamin C serum, waiting 20 minutes, and then continuing with the rest of their routine. (Please note that non-LAA Vitamin C serums are not impacted by the below factors, so disregard if your Vitamin C is not LAA.)I realized that they were struggling with information overload, so I had to change up my approach.Actually, I get this kind of question a lot, and I too was overwhelmed when I started delving into the sciencey side of skincare, so I decided to go for a less technical approach in my reply:Yep, I just equated Vitamin C serum to a petulant, jealous, emo boyfriend. But hey, it worked!If you want a more technical explanation, you can check out my recent post on pH testing with a digital meter where I talk about the specific ranges of BHA and AHA, and how the pH of my particular BHA and AHA of choice forces me to stagger them with 20 min in between. If any of your products are not finicky about the pH they are in, or within the same pH range, I don't see any reason why you couldn't layer them, but I prefer to err on the side of caution.LAA-based Vitamin C serums oxidize when exposed to light (or heat, so store it in your fridge between uses) so I wouldn't recommend waiting out the 20 minutes in front of a large window (or you may end up looking like Snooki until you wipe off the residue). Some people apply it and wait in the dark, like ultra-glamorous bats, but I've never gone that far.AHA makes you photosensitive, so for the love of anti-aging,. Don't just put it on at night and then expect that it will be safe to go out sunscreen-less the next morning, because we're talking an overall shift in your skin. Not only will you lose out on all the goodness an AHA gives you, you will be making things worse. You should already be wearing sunscreen daily no matter what, but you may need to boost up the strength when you add actives, AHA, BHA, LAA, whatever you are using.BHA has to be in higher concentrations to work (1-2% at minimum, and I have seen suggestions as high as 3-5% is needed for those with very clogged/oily skin), but I have heard that Korea has limits on OTC (over the counter) products containing more than 0.5% BHA. Hence my rage and frustration with the Sidmool Dual Effect BHA Gel and the explanation as to why it wasn'tanything. So do some extra research to make sure your product is high enough.AHA (well, BHA too) comes in many forms, the most common is Glycolic Acid which doesn't agree with some people's skin. That doesn't mean that you have to give up AHAs, you just need to find alternatives, such as Mandelic acid. Same with BHA; if your skin doesn't like Salicylic Acid, you may have to dig around to find a BHA that works for you.Do your research before trying any actives, because unlike the creams and lotions and potions you are used to, you can actually damage your skin if you goof up. They're magical and wonderful and they're skincare mana from above, but don't mess with them. Research.Lastly, that's also my disclaimer: I am not a licensed medical professional, I am just a skincare nerd with an unhealthy love of google scholar and a willingness to devote hours into research.All the best,-CatDid this post help you put your products in their place? Hit me up on Facebook or Twitter and let me know!Have something you'd like to share with me in general? Snap a pic and tag me on Instagram at @snowwhiteandtheasianpear because I'd love to see it!