How to choose lash adhesive?
A special glue is used for eyelash extensions. Its main ingredient is cyanoacrylate (90% or more). Amount of this agent and its proportion to other components directly influences setting and wearing time.
Eyelash adhesives vary in:

1. Setting time.
How fast the adhesive hitches upon contact of two surfaces that need to be glued together. 0.5-1 seconds – super-fast, suitable for professionals 1-2 seconds – fast, suitable for both professionals and beginners 3+ seconds – slow, suitable for beginners

2. Viscosity
Liquid glue is better for the classic style or for the "wrapping" extension technique. Thicker glue is better for volume and super volume.

3. Color.
Classic black glue is mostly used for black extensions. Clear glue will be perfect for colorful or brown extensions.
Optimal glue work criteria:

1. Humidity
Cyanoacrylate glues polymerize in a matter of seconds under humidity's influence. The higher room humidity is, the faster it will dry. Although, there's an optimal humidity range that allows the glue to work properly. Relative humidity of 40 – 70 % provides the best conditions for good steady hitching. If humidity is too low (< 30%), setting time will be too long. If it's too high (>80%), a so called explosive polymerization happens, leading to the lesser hitch efficiency.

2. Temperature
Temperature affects any chemical reaction's time hugely. Raising the temperature 10°C doubles polymerization time. That applies to cyanoacrylate glues as well, but there's a certain interval that allows them to work properly, which is 20 – 24°C. Remember that glue viscosity changes in higher or lower temperatures.

3. Surface condition
When working with cyanoacrylate glues, it's important to keep your working surface clean and monitor pH. If your surface has high acidity, setting time increases. And if it has high alkalinity, it, on the contrary, decreases. Also, explosive polymerization might happen, degrading glue properties as a result. It's a known fact that healthy person's skin has a neutral pH of 5.5, so a special primer is used to raise the alkalinity level.

You should constantly renew your glue drop during the procedure! It should be changed every 20-40 minutes depending on your room microclimate, glue base and the glue itself.

Important note: Glue polymerize (dries) when it comes in contact with moisture. When in direct contact with water, a "shock" polymerization happens, but it doesn't have any negative effect on adhesive properties.
Side effects of working with cyanoacrylate glues incorrectly:

1. Respiratory organs:
Respiratory organs can get irritated. Being exposed to high concentrations of adhesive fumes for long amounts of time may cause a chronical reaction in sensitive people. In a dry environment with less than 50% humidity fumes may irritate eyes and respiratory organs.

2. Skin irritation: Glues hitch to the skin in mere seconds. They are considered to have low toxicity, but allergic skin reaction is still possible because of polymerization.

3. Eye irritation: Glue can irritate eyes. In a dry environment with less than 50% humidity fumes can irritate our eyes and cause lacrimation.