One of the first things lash artists learn about adhesive is to watch the humidity in their lash room. The part that is sometimes missed is that there is no single humidity number that is perfect for every adhesive.
Professional lash adhesives can have different recommended working conditions. Your first reference should always be the manufacturer's directions for the adhesive you are using.
Why Does Humidity Matter?
Many professional lash adhesives are cyanoacrylate based. Moisture is involved in the curing process, which is why changes in humidity can change how an adhesive behaves.
This does not mean higher humidity automatically creates better retention. If your adhesive begins curing faster than your application speed can comfortably handle, your working time may become too short.
The opposite can also happen. Different room conditions can make an adhesive feel slower than what you are used to.
Your Speed Matters Too
Two artists can use the same adhesive at the same humidity and still have different experiences.
One artist may move from dipping to attachment very quickly. Another may take longer to position the extension. The same adhesive may suit one artist beautifully and feel too fast for the other.
This is why copying another artist's exact humidity setup is not always helpful.
Use Your Hygrometer as a Tool
Know your temperature and humidity, but also pay attention to how your adhesive behaves when retention is good.
Keep a simple record of your room conditions, adhesive, bottle opening date, and retention results. Over time, you will learn what normal performance looks like in your own lash room.
For consumers, you do not need to manage any of this yourself. A professional lash artist should be monitoring the products and environment used during your service.
The Takeaway
There is no universal perfect humidity for lash extensions. Follow the recommended range for your adhesive and learn how it behaves with your application speed and environment.
The number on the hygrometer is information. Knowing what to do with that information is the skill.
Learn next: What Temperature Is Best for Lash Adhesive? Why Is My Lash Glue Drying Too Fast? What Is Cyanoacrylate in Lash Adhesive?