When adhesive feels slower than usual, do not immediately throw away the bottle.
First, define what you mean by slow. Is the extension moving after placement? Are you having to hold it longer? Are neighbouring lashes more likely to become attached? Does the adhesive simply feel different from what you normally experience?
Those details help you troubleshoot the actual problem.
Check What Changed
Start with your environment and product. Check your temperature and humidity, the age of the opened bottle, how it was stored, and whether you are using the same adhesive you normally use.
Then consider something artists sometimes overlook: you may have changed.
As your technique improves, you often become faster. An adhesive that felt perfect when you were newer may eventually feel slow because your application speed has increased.
That does not necessarily mean the adhesive became worse. Your needs may have changed.
Do Not Diagnose by Feeling Alone
Compare what you are experiencing with actual retention and application results.
If the adhesive feels different but retention remains excellent, that gives you different information than an adhesive that feels different and is causing application problems across several clients.
The Takeaway
Before replacing your adhesive, identify what is actually happening. Check the environment, bottle condition, storage, and your own working speed.
Sometimes the product changed. Sometimes the room changed. Sometimes the artist improved.
Learn next: Why Is My Lash Glue Drying Too Fast? How Often Should Lash Adhesive Be Replaced? What Humidity Is Best for Lash Extensions?