Whatever said in the earlier posts are good reasons for using Kapton tape but, it gives low angle diffraction peak and compared to Kapton tape I prefer magic scotch tape, if I am going to use at ambient conditions, compared to Kapton tape the absorption of magic  scotch tape is less.

because of  Its high mechanical and thermal stability and high transmittance to X-rays , and that make it the preferred material. It is also relatively insensitive to radiation damage.

moreover, Kapton is regularly used as an insulator in ultra-high vacuum environments due to its low out-gassing rate.

Also, at high temperature diffraction, you find temperature room, for example HTK1200, equipped from Kapton with a graphite deposit (T> 1000 °C) or aluminum (

Kapton tape is also used to cover highly active material (some pharmaceutical substances) on the holders (to protect people who manipulate it). The powders are then measured (XRPD) through it, as X-rays can go through...

Whatever said in the earlier posts are good reasons for using Kapton tape but, it gives low angle diffraction peak and compared to Kapton tape I prefer magic scotch tape, if I am going to use at ambient conditions, compared to Kapton tape the absorption of magic  scotch tape is less.