Adhesive Temp/Humidity Guide

The importance of adjusting to the humidity – eyelash extension glue in low humidity to high humidity

When it comes to setting the stage for optimum adhesive performance, a safe eyelash extension application, and long-lasting eyelash extensions, humidity plays a large role than most Lash Artists or Consumers think.

To eliminate the potential for humidity negatively impacting your eyelash extensions, your line of defense is to control and regulate your environmental humidity and arm yourself with application knowledge that allows you to adapt and counteract the potential negative impact.

If you live in a country where there are different seasons, you might find that your results will vary depending on the time of year. Using adhesive in the winter will be very different than in the spring, summer or fall.

The same is valid if you live in a climate where there are no seasons and most of the year it is either very humid and in periods even more humid (during rainy seasons) - or very dry and in periods even dryer (when needing to use room heaters night and day)

Here some tips for managing your results during the different seasons/climates:

What is humidity?

Humidity is the concentration of water vapors present in the air.

The amount of water vapor needed to achieve saturation increases as the temperature increases. As the temperature of a parcel of air decreases it will eventually reach the saturation point without adding or losing water mass. The amount of water vapor contained within a parcel of air can vary significantly.

For example, a parcel of air near saturation may contain 28 grams of water per cubic meter of air at 30 °C/86°F, but only 8 grams of water per cubic meter of air at 8 °C/46.4°F.

Three primary measurements of humidity

- Absolute humidity describes the water content of the air and is expressed in either gram per cubic meter or grams per kilogram.

- Relative humidity, expressed as a percentage, indicates a present state of absolute humidity relative to a maximum humidity given the same temperature.

- Specific humidity is the ratio of water vapor mass to total moist air parcel mass.


Why does humidity play an important role in the lash extension application?

All eyelash extension glues contain cyanoacrylate. And cyanoacrylate reacts strongly to humidity - or the lack of it:

- In case of too high humidity level in the air, the cyanoacrylate in the glue dries too fast, causing curing shock or crystallization (or blooming) of glue happen.

- In case of too low humidity level in the air, the cyanoacrylate in the glue does not dry fast enough and lashes will not get attached well enough.

Thereby, the humidity level in your lash room decides how well the lash adhesive works.

How does the cyanoacrylate cure?

Unlike some adhesives that cure by evaporation, or heat, cyanoacrylate owes its special instant curing process to the presence of moisture, which reacts instantly on exposure to air, providing there is even just a small amount of relative humidity in the atmosphere.

Humidity plays an important part in:

  1. The speed at which your adhesive cures during your lash application.
  2. Reducing the potential for adverse reactions to you and your client.
  3. The strength and longevity of your extended lashes.

By maintaining a controlled environment and keeping humidity in the ideal range, this helps reduce the chance of irritation and other adverse reactions during and after your lash application. This also promotes an optimal performance of your adhesive that results in strong, long-lasting eyelash extensions.

Remember to always use a hydrometer to determine the humidity in your work space.


What happens if humidity is too high?

Too high humidity = poor attachment

If humidity is too high it can cause shock polymerization of the adhesive. This ‘shock’ polymerization can lead to a shrinking process of the adhesive layer and weaker bonds.

- Poor attachment. In high humidity, your adhesive will cure faster than usual. The adhesive may partially cure before you’re able to attach, resulting in lash extensions not attaching well.

- Crystallization (or Blooming). This can also happen if humidity is over 65%. It will appear on your adhesive tray and the lash extensions.

The ideal RH for life, in general, is 45-60%.

Humid Summers and/or climate

Summer can present different challenges for lash artists. Depending on the area you live in, Summers can be very dry or very humid. As such, the best eyelash extension glue for you will depend on where you work.

If your lash salon is in an area with high humidity during the Summers, then there are things you should take into consideration.

As mentioned before, humidity speeds up the curing process for eyelash extension glues. If your humidity is high, then you need to choose the glue with slower drying speed.

Not having enough ‘wet’ glue can result in having the eyelash extension glue setting before the lash extension is attached. This can result in a weak bond and cause lashes to start falling off.

If you are applying eyelash extensions in high humidity and temperature, our recommendation would be to use medium-thick viscosity glues.


What happens if humidity is too low?

Too low humidity = too long curing time

Too low in relative humidity will slow everything down and your adhesives will take longer to cure which can also lead to sensitization as the vapors are looking for moisture and are naturally attracted to the moisture around the eyes and nose.

- Adjacent lashes may end up sticking to one another. This is caused by the adhesive taking too long to cure during attachment.

- Lashes may lean or slip. Lashes might lean to the side or slip upon placement. You’re not going to feel that instant, magnetic attachment.

- Increase in adverse reactions. This includes eye tearing or burning to inflammation and allergic reactions.


Winter heating

For many people, the Winter months typically involve turning on your heater to stay warm and comfortable. This can cause an issue because your heater will affect the humidity levels in your space.

Your heater typically creates an environment that is dry with low humidity and this will create an issue if you do not adjust. If you must use a heater in your lash room, make sure the hot air is not blowing directly to the work station. This is an important point for lash artists in colder climates like in the Northern US States, Canada, and a great part of Europe.


Dry Summers and/or climate

If you live in a place where you have very dry summers or in a very dry climate, and the RH is under 45%, you should use a humidifier.

Although humidifiers can be great in helping you achieve the right environment, it may still be difficult to get the optimal humidity levels when the heater is running during the coldest months.

What’s the ideal humidity for a lash studio?

For optimal performance, your humidity levels must be between RH 45-60%.

Although our adhesives have been tested and categorized by humidity, there are many other varying factors that could affect the performance of your adhesives.

There are optimal conditions for adhesives to receive the best results for your clients, these include keeping your adhesive fresh, working in ideal temperatures, and many others. 


How to set the ideal humidity for your lash studio?

First of all, you should purchase a device that allows you to measure both temperature and room humidity. For example something like this:Hygrometer Humidity Indicator. This product is only an example and not a direct recommendation.

On top of that, you have to do some investments in the lashing environment. If you don't do that, you risk losing your clients one by one, because they will not be returning to you after their new lash extension keep falling off only a few days after applying them. So this part is really important:

In high humidity conditions:

  1. Use a dehumidifier - a proper freestanding unit, not a tiny thing on your window mantelpiece. Bring the humidity down to 45-60%
  2. Use an air conditioner that helps you to keep the lashing room at the right temperature. A simple fan is not enough. Keep the temperature at 22-26 degrees Celsius/ 71~79 degrees Fahrenheit.


In low humidity conditions:

  1. Use humidifier. Bring the lash studio humidity up to 45-60%
  2. Use nano mist. If the humidity is still low and/or the air is very dry outside of your salon, then you should consider purchasing a nano mist. Its fine mist helps to speed up the glue drying process. Here is an example: Nano Mister or face steamer or any type of misting device. 
  3. Adjustable heater. During the Winter use a heater that can be easily adjusted or an air conditioner with a heating feature and keep the room temperature at 22-26 degrees Celsius/ 71~79 degrees Fahrenheit.


What to do when room humidity cannot be adjusted?

One of the most effective adjustments you can make is changing the type of adhesive to use.

- If your humidity is too low, you’ll need to use FASTER DRYING glue to speed up the attachment. Fortunately, it is also easy to add humidity by investing in a humidifier or nano mister.

- If your humidity is too high, pick up SLOWER DRYING glue to give yourself enough time for the attachment. But be aware too high of humidity can cause the glue crystallization (blooming effect) and result in poor retention.


Useful tip: Does temperature matter, too?

Lash adhesive's best conditions for lash application is between 22-26 degrees Celsius/ 71~79 degrees Fahrenheit with good air movement and/or local extraction at the point of application. Cyanoacrylate in lash adhesive gets affected a lot more by humidity level and less by temperature.

Temperature DOES affect the viscosity of the lash adhesive because after all, lash adhesive is liquid.

Just like any liquid, when the temperature drops, lash adhesive tends to solidify itself like it’s getting frozen. The viscosity of the ‘frozen’ adhesive is higher than usual so it will take longer to dry. In contrast, when the temperature soars, lash adhesive liquefies itself like it’s getting melt. The viscosity of the ‘melt’ adhesive is lower than usual so it will take faster to dry than usual.

The change in temperature can come as a surprise element to your application. To ensure consistent results and good retention, we recommend maintaining the room temperature at 22-26 degrees Celsius/ 71~79 degrees Fahrenheit.