Q&A: Everything About Eyelash Extension Adhesive

About The Science of Eyelash Extension Adhesive

What are the components of eyelash extension adhesive?

Typical components of eyelash extension adhesive are as the following:
90~95% of Cyanoacrylate
5~10%  of Complex compounds such as stabilizer, thickener, hardening accelerator, colorant, etc.

What are the different types of Cyanoacrylate?

lash glue cyanoacrylate chart

Methyl type is a toxic substance. Therefore, it is strictly classified and used even for industrial purposes. Methyl type can dissolve the proteins and lead to permanent blindness. You should NEVER choose an adhesive contains this.

Ethyl type is mostly used for eyelash extension glue. Its drying time is fast and the adhesion is strong, but the odor and irritation are quite strong. 

Alkoxy type is 8 times more expensive than the Ethyl type Cyanoacrylate. It is developed as a hypoallergenic and low odor type product.


Butyl type is an instant adhesive that is made for hypoallergenic and low odor aimed at the use of medical and veterinary. Compared to Ethyl, its drying time is slower and the adhesion is weaker. It is mostly used for medical adhesive or thickener in cosmetics. 


Methoxy type is the least irritating and odorless among all the Cyanoacrylates. It is developed to improve the problems caused by the irritation and odor of Ethyl and Butyl-type glue. Its drying time is slower and the adhesion is weaker, compared to Ethyl and Butyl-type glue. 

sensitive glue from bl lashes

Is there any eyelash extension adhesive that doesn’t contain Cyanoacrylate?

All types of eyelash extension adhesive use Cyanoacrylate which is the only one-component that can be hardened under the circumstance genuinely.

There is no other substitute glue that can replace the retention and adhesion of current eyelash extension adhesive. 

Humidity, Climate and lash extension adhesive

What is the ideal temperature and humidity when using adhesive?

As the eyelash extension adhesive reacts and dries with humidity, the drying time is closely related to the humidity than anything. For all eyelash extension adhesives, Its recommended humidity is 45 to 60%

The higher the humidity, the shorter the drying time and time of use the adhesive after the dispense. On the contrary, the lower the humidity, the longer the drying time and time of use after the dispense. However, if the humidity is over 70%, the drying time of glue will be slower again.

Let us give you an example! BL’s DIU glue has 2 to 3 seconds of drying time. If the humidity is 45%, its drying time is 3 seconds and if the humidity is 60%, the drying time is 2 seconds.

Even if the humidity exceeds 60%, the drying time will not be faster than 2 seconds. Instead, the drying time will be maintained at the speed of 2 seconds for a while and then it will gradually slow down after 70% of humidity.

When it comes to the temperature, the adhesion and components of adhesive do not change from -50 to 60 degrees Celsius. However, it is recommended to maintain 22 to 26 Celsius degrees (71~79 degrees Fahrenheit) for uniform viscosity and drying time.

If the temperature is high, the viscosity of glue gets thinner and the drying time is shorter. If the temperature is low, the viscosity of glue gets thicker and the drying time is longer.

For more information, this article explains well about the secrets behinds lash extension retention and humidity.

lash extension glue tape

Is there any glue that does not get affected by the climate?

No adhesive gets not affected by humidity, since cyanoacrylate, a component reacts with moisture and dries, is the main component of the glue.

Whereas temperatures affect the viscosity of the glue, so it has less influence on the adhesive than the humidity does.

Of all the BL glues, Ultra Plus, Ulbon, and Q-1 glue are the least affected adhesive by oil, moisture, and external environment. 

Which adhesive is suitable for hot and humid weather?

Whichever glue you use, it is important to adjust the optimal temperature and humidity. Use an air conditioning system or a fan to lower the temperature if your room temperature is too hot.

Also, equip a dehumidifier or desiccant and ventilate the room regularly so that you can lower the humidity. By doing so, you can adjust the temperature and humidity.

After that, choose a glue according to your preference and skill level.

Humidity tends to be high in hot countries and seasons. Also, the viscosity tends to get thinner due to the high temperature. We recommend to use a glue that has a bit of viscosity like DIU Glue (2~3 second drying), Glam Glue (4~5seconds drying). 

However, it's good to know that in hot and humid weather, excess amount of oil is secreted on the skin and eyelashes. So it is recommended to use a glue that is more resistant to water and oil like Fina Glue (4~5 second drying) Q-1 Glue (4~5 seconds drying) .

BL blink eyelash extension adhesive for hot and humid climate

BL eyelash extension adhesives for hot and humid climate

Which adhesive is suitable for cold and dry weather?

Whichever adhesive you use, it is important to adjust the optimal temperature and humidity.

First, by using a humidifier, increase the humidity of the room. Then, using a heater, increase the temperature of the room. After that, choose the glue according to your preference.

If your room humidity is still below the ideal humidity range (45~60%), Choose a lower viscosity glue or faster drying glue. 

Humidity tends to be low in cold countries and seasons. Also, the viscosity tends to get thicker due to the low temperature. Therefore, it is not recommended to use a glue that has thick viscosity. Otherwise, you can choose a glue according to the procedure speed.

For the fast-drying, thin viscosity glue for the cold and dry climate, we recommend Mach Glue (1~2seconds drying), Ultra X Glue, and Ultra Plus Glue (3~4seconds drying).

BL blink eyelash extension adhesive for hot and humid climate

BL eyelash extension adhesives for cold and dry climate

Retention and lash extension adhesive

What are the best ways to improve retention?

Many factors can affect retention of eyelash extensions. Among those factors, there are two major ways to improve retention.

ONE. Adjust the amount of glue and then attach the lashes correctly with the accurate technique.

TWO. Practice appropriate use of before & aftercare products. Removing the oil on the natural lashes with Lash Primer before the procedure and using Coating Sealant after the procedure can help improve the retention.

What causes adhesion and retention decrease?

If you have problems with the retention of eyelash extensions, it is recommended to check these factors:

1. Materials:
Compatibility of extension lashes and adhesive, Deterioration of adhesive performance, Inappropriate storage method and use of products can be the reasons.

2. Technician: Incorrect attachment, Incorrect amount of adhesive, inexperienced use of pre-application treatment can be the reasons.

3. Client: Inexperienced aftercare, Conditions of natural eyelashes, Health conditions can be the reasons.

4. Environment: High temperature and high humidity, Cold and dry environment, Rapid temperature difference, Procedure in a non-ventilated place can be the reasons.

lash extension glue bl lashes

Lash Extension Adhesive Recommendations

Which adhesive from BL Lashes is the best?

It is impossible to say which adhesive is the best because that is highly subject to the treatment environment, proficiency of the technicians, and preference of individuals.

You should decide what is the best glue for you by considering the room environment, speed of the procedure and client's condition.

For example, if the technicians use a 1~2 seconds of fast-drying glue when their skill level actually take 3~4 seconds to apply extension lashes on natural lashes, the retention will inevitably decrease because the extension lashes are applied to natural lashes after the glue is already a bit dried.

Another example would be if the technicians use the slow drying glue when their speed of procedure is faster than that, it is not an appropriate glue as well because it will slow down the procedure.

What we can recommend is to ALWAYS adjust the room environment (humidity & temperate) to the ideal setting for the eyelash extension glues to perform more consistently. In this way, you'll soon find the best lash adhesive works for you.

Can you make a recommendation by the skill level?

For Experts: Mach Glue, DIU Glue
For intermediates: Ultra X Glue, Ultra Plus Glue, Fina Glue
For Beginners: Q-1, Mild, EZ, Ultra Bonding, Ulbon

*The above-recommended glues are the guideline according to the drying time. We recommend you to make extra considerations based on your room humidity, temperature, preferred viscosity and fume level.

Which glues are best for volume extensions?

Volume extension glues can be divided into two main categories; handmade volume glue and pre-made volume glue.

For handmade volume lashes, as you need to make a fan, it is recommended to use a fast-drying glue or the one that has a bit high viscosity. MACH glue is suitable for those who are fast when applying extension lashes. Glam glue is suitable for those who want a glue that has longer drying time and thicker consistency.

For pre-made volume lashes, it is recommended to use a glue that has fast drying time and low viscosity. This is because the adhesion parts of pre-made volume lashes are wide and glue can be applied excessively on those wide areas which will result in surrounded lashes sticking to them.

MACH glue is suitable for those who are fast when applying extension lashes. Ultra X or Ultra Plus glue is suitable for those who want a glue that has longer drying time. 

Fast drying lash extension adhesives from BL blink lash

BL Fast-drying eyelash extension adhesives

Are there any waterproof or oil-proof glues?

The instant glue becomes a solid acrylic like plastic after hardening. The surface might withstand a certain amount of water, but the sealing effect of the bonded area itself is not very good. Thus, it is hard to call it a waterproof or oil proof.

Eyelashes do not fall off immediately when they come into contact with water or oil. However, the strength of the adhesion drops dramatically due to hydrolysis.

2 to 20 seconds after the extensions, the hardening progresses more than 93 to 97%. Hence, it has little possibility of forming efflorescence once they are dried 1 to 2 minutes with the fan.

However, the possibility of forming efflorescence increases when the amount of glue is excessive as the hardening takes more time.

It takes about 24 to 48 hours for glues to be dried completely. Therefore, it is recommended to use a serum or coating sealants after 24 to 48 hours from the extensions.

Can you choose adhesive according to the shape of natural lashes?

You can choose various types of glues according to the type of hair, depending on whether it is damaged or it has different shapes of hair follicles.

For customers with curly eyelashes, using a low viscosity glue will decrease the retention of the extensions. In this case, it is better to use a glue that has high viscosity.

How to store lash extension adhesive

How long is the expiration date (Shelf-life) of the adhesive?

3 to 6 months* when not opened, 1 month once opened.
(*Why 3 to 6 months? Low fume, sensitive adhesives expire faster than normal adhesive)

When the adhesive is contained in its bottle, it is hard to harden because the surface area that is in contact with the air is small, compared to the capacity of the liquid.

However, once it is applied to the surface material like a jade stone, as the surface area becomes wider, the hardening reaction becomes active and the whole area of the adhesive starts to hardens.

Since the hardening of adhesive is always in progress (even when it's kept in the bottle), its potency keeps on deteriorating even if it is not opened and used. The period from the moment it is manufactured to the state of unavailability to use is called the ‘expiration date’.

It is important to keep the appropriate temperature and humidity and pay attention to the storage methods to prolong the expiration date.

What's the best storage methods for the adhesive?

Eyelash extension glue is a reactive type adhesive. Therefore, it is important to manage the environment in the treatment room and the storage area.

The glue will not deteriorate at temperatures within -50 to 60 Degrees celsius . Hence, store it where it is cool and dark, avoid the direct sunlight and high humidity instead of storing it in the refrigerator.

When storing it, the deterioration of the glue is depending on the humidity rather than the temperature. Therefore, as long as the humidity is low, it can be stored in a place where the temperature is high. However, be aware that, in most of the high-temperature areas, humidity is high as well.

BL Lashes glue has a desiccant in the zip-lock bag together, to prevent the performance deterioration of it, which is caused by moisture. When storing the glue, put the glue container with the desiccant together as it was manufactured and store it upright with the zipper sealed.

To manage the glue effectively, write down the purchase date and opening date on a glue zip-lock bag.

Read this post: How to Properly Care for Lash Extension Adhesive for the in-depth tips and how to's.

Can eyelash adhesive supplies be stored in a refrigerator?

The glue hardens by the reaction with moisture in the air. The most stable storage place is in the dark and cool place.

A refrigerator is not an appropriate storage place as it can affect the performance of glue adversely by causing a dew condensation, not only on the outside but also on the inside.

In the past, a dry place that can be easily found was a refrigerator which absorbed moisture.

However, it is not recommended as it keeps and supplies the moisture nowadays. If you must use the refrigerator inevitably, seal it as much as possible when storing and put it on the room temperature at least 2 hours before use.

Is there a way to use the lash adhesive for a longer time?

To use the lash extension glue for a long time, pay attention to the precautions and storage methods.

When discharging the glue, lift the outlet from the surface slightly as the dust or dirt may be sucked in the container.

Wipe the glue nozzle with a piece of paper immediately after use.

Close the lid tightly and seal it instead of just placing a lid on it to prevent the contact with moisture.

As it was manufactured, store the glue in a sealed zip-lock bag with the desiccant.

Store it in a dry and cool place, avoid the direct sunlight.

In humid season or environment, you can purchase extra desiccants in the glue zip-lock bag. By doing so, you can prolong the expiration date. 

Can you make glue bottles air-tight so it can last longer?

Eyelash extension glue might expand and explode if it is contained in a "air-tight" bottle.

Therefore, it is impossible to contain the glue in "air-tight" containers. Hence, do not transfer the contents to an ordinary plastic or glass container, as eyelash extension glue is manufactured with the special PE material container. 

Eyelash extension glue might expand and explode if it is contained in a "air-tight" bottle.

Allergy & Irritation related to lash extension

Why does the glue allergy or irritation happens?

As the glue hardens, gas is generated, and at this time, the traces of glue are mixed in the gas. Glue tends to settle on the moisture and that irritates the eyes. As a result, it causes sore eyes because there are tears on the surface of the eyes.

Some technicians wipe the glue onto the eye patches during the procedure, to adjust the amount of glue. This should be avoided as it can irritate the eyes more because the glue hardens on the surface of eye patches.

If the customer tears during the procedure, there is a high possibility that their eyes are not closed completely. Therefore, dry those tears with a fan and proceed with the extensions after checking their eyes thoroughly.

If they still have problems with irritation, it is better to use hypoallergenic glue.

Find out what's the best lash extension glue for glue-sensitive clients

Technicians can also reduce the irritation by wearing a goggle and mask. Additionally, if you put BL’s anti-allergy gel right next to the glue, you can reduce the irritation more dramatically.

Is eyelash extension glue harmful to the human body?

Although there may be short-term sore eyes and bloodshot eyes due to glue irritation, cyanoacrylate is not toxic, unlike ordinary cyanide materials.

It is not accumulated in the body and completely decomposed and discharged out of the body in about 2 months. As a result, it is used as a medical adhesive. 

I have a hordeolum (sty) in my eye.

A sty is caused by infections of the lachrymal glands and auxiliary glands of the eyelids, mainly by staphylococci. Since the germs cannot reproduce in the glue, it is not caused by the glue itself.

As it is an infectious inflammation, it is more likely to be caused by unsanitary hands or contaminated treatment environment (tools, subsidiary materials) rather than troubles result from the glue.

Always make sure to disinfect your hands and tools before the procedure and pay attention to keep dust from accumulating on subsidiary materials such as extension lashes and tapes. Also, do not touch the extension lashes and glue plate with your hands.

You might find this post useful: How to Sanitize your Lash Extension Tools

Why are my eyes itchy and irritated?

If the extension lashes are extended to multiple strands of natural eyelashes instead of a single strand or attached with the downy hair, it may be irritating or itchy. It is important to check the lashes after the extensions, to see if there are any attached eyelashes beside.

Your eyes may also feel irritated when it is attached to the mucous membranes instead of away from the skin, or the lump is on the lashes due to the excessive amount of glue.

Read this post to learn How to differentiate 'glue allergy' and 'eye irritation'

Otherwise, it can be caused when the treatment environment is not clean or the customer is immunocompromised due to the bad condition.

Therefore, always keep the treatment environment clean and check the customer’s condition.

Which are fast-drying, but hypoallergenic glue?

Currently, it is hard to make a quick-drying glue with the hypoallergenic and low odor cyanoacrylate base.

Although hardening speed can be increased by adding a hardening accelerator called ‘Toluene’, it is not used in BL Lashes because Toluene is harmful to the human body.

To find the best lash extension glue for the clients with glue sensitivity, read this post: The Best Lash Extension Adhesive for Sensitive Eyes

BL Low Fume & Odor eyelash extension adhesives

Lash Extension Troubleshooting

What happens if I use extension glue without shaking?

Eyelash extension glue contains not only cyanoacrylate that is for adhesion, but also other complex compounds such as stabilizer, thickener, hardening accelerator, pigments, and so on.

Then, there will be a separation of layers caused by a difference in the density of each component.

That is why it is necessary to shake the glue to mix all the components of the glue properly and ensure the optimum performance and retention of the glue.

Why does the color of my glue look cloudy?

If you don’t shake the extension glue enough, the color of the glue might look like it’s faded and cloudy.

If you see a layer separation even though you have shaken it sufficiently more than 1 minute, it can be a manufacturing problem that can happen once in a while. If that happens, contact the customer service with the LOT number (usually written on the bottom of the products).

Why is my adhesive sticky?

Cyanoacrylate reacts with the traces of moisture in the air or on the adhesive surface and then hardens instantly.

When it is contained in its container, it is hard to harden because the surface area that is in contact with the air is small, compared to the capacity of the liquid. However, once it is applied to the material, as the surface area becomes wider, the hardening reaction becomes active and the whole area hardens in sequence.

If the glue becomes stickier than usual, stretches like a thread, or the hardening takes longer than before, then the performance is already deteriorating. Therefore, it is better to discard the glue even if there are some contents remained.

Since the hardening of glue is always in progress, its function is kept on deteriorating even if it is not opened and used. The period from the moment it is manufactured to the state of unavailability is called the ‘lifetime(expiration date)’.

It is important to keep the appropriate temperature and humidity and pay attention to the storage methods to prolong the lifetime(expiration date).

My lash adhesive bottle is clogged?

The clogging of the discharge port is caused by gas or bubbles that are generated in the container when discharging.

And then, the bubbles rise with glue and form a layer at the entrance of the outlet. If the glue layer is visible at the entrance of the outlet once opened, the layer must be removed by discharging it.

This way, it prevents the outlet from clogging, but it also keeps the glue fresh for a long time by removing the glue layer that is exposed to the air.

It can also happen when the glue bottle is kept on its side or when it is shaken vertically instead of side to side. In this case, use a glue pin that is contained with glue to pierce the clogged hole. 

What's the white powder on the glue bottle's surface?

Have you notice a white powdery material on the surface of your glue bottle?

This happens when particles like cyanoacrylate are vaporized in the air and contacted by moisture.
It is not a product defect, but a natural occurrence for eyelash extension glue because normally glue bottles release a tiny amount of vaporised gas while stored in package and when the gas is touched by moisture in hand, it leaves this white powdery particle on the surface.