Troubleshooting Slow Warm-Up in Kapton Heater

https://thermal-engineering.trexgame.net/beginner-s-guide-to-silicone-heater-what-to-know-before-you-specify-one

A kapton heater can solve a simple problem: place useful heat close to a part that needs it. The best result comes from a clear plan. Shape, power, contact, and control all affect the final behavior