Skincare Layering

[MacindaLou]

I’m trying to figure out the best order of products for my nighttime routine. The products I’m getting a bit confused on are my Hyaluronic acid and Polyglutamic acid. These are humectants, and can be used together. I’ve seen that they should be applied in damp skin after cleansing to lock in that moisture.
However, my problem comes from adding in other products. I use retinol at night, and my research said it should be applied before the humectants. Retinol can only be applied on dry skin though, which wouldn’t work for the HA and PGA.

I also looked into using the acids with niacinamide, and I couldn’t find a straight answer as to how to layer that either.
These products all work well together, but I just don’t know the best order in which to apply them. 

For more context, these are the exact products I use:

Retinol: Differin 

HA and PGA: The Inkey List

The INKEY List Hyaluronic Acid (HA) Hydrating Face Serum 1 oz/ 30 mL 

The INKEY List Polyglutamic Acid 

Niacinamide: The Ordinary (I’ve looked into the Peach and Lily Glass Skin Refining Serum as well, but I think that a bit too many ingredients for me to figure out right now.)

The Ordinary Niacinamide 10% + Zinc 1% Oil Control Serum  

[WinglessOne]

@MacindaLou  Consider layering products like this: 

1. Cleanser 
2. Hyaluronic acid and PGA (in whichever order you want), applied to damp skin 
3. Niacinamide 
4. Moisturizer, applied to damp skin; let it settle into your skin before the next step 
5. Differin (adapalene) 

This method ensures your skin is well hydrated and moisturized before you apply adapalene. Differin will still work this way; if your moisturizer's not a petrolatum-based balm, then it's not nearly occlusive enough to stop vitamin A from reaching your skin. This can also buffer any irritating side effects you might otherwise experience with adapalene. 

Niacinamide can be layered with both those humectants, by the way. Niacinamide plays nice with nearly everything.