I'll give a little more background as to what my experiences have been
Spot Size: I’ve had some individuals insist on using an 18 mm spot size. The justification was that there would be less overlap and therefore it would be safer. With a test spot of an 18 mm spot size and a fluency of 10 Joules, the hair was completely removed. However, I noticed the texture of my skin had changed for the worse and looked somewhat scaly with a large amount of small tannish dots which looked like hypopigmentation. The skin also seemed reddish, even weeks after the test spot.
I should note that I followed all of the pre and post procedure instructions, including not working out before or after, staying out of the sun, not applying excessive heat to the area, and using sunscreen.
Fluency: I’ve learned that as the spot size decreases, joules can be increased, and as the spot size increases, joules should be decreased. Despite my insistence that an 18 mm spot size and 10 Joule fluency resulted in adverse effects on the texture of my skin, the next technician I saw insisted that the fluency was too low to have any effect (even though my hair had disappeared). She insisted I stay with an 18 mm spot size and increase the fluency to 18 Joules. The adverse texture effects on my skin resulted again from an 18 mm spot size and fluencies of 18 Joules and 20 Joules. Regardless, the hair was once again completely removed.
Pulse Duration: The largest discrepancy I’ve seen has been for Pulse Duration. I’ve had some say 3 ms is best for dark skin, while others have said a longer pulse duration approaching 100 ms is best for dark skin because it spreads the heat out over a longer period of time, making the procedure safer. Others have said 20 ms should be the max, and others that this setting doesn’t even matter and is never changed from 3 ms. Does anyone know which pulse width should be used for dark skin? Longer or shorter?
Cryo: The technicians I’ve asked about Cryo say there’s no difference between 40/20 and 30/20. Can someone confirm or deny this?
Settings that worked for me: I’ve noticed the settings which worked best were with a 12 or 15 mm spot size combined with a fluency ranging from 16-18 Joules and a Pulse duration of 10 ms. As stated earlier, whenever a spot size larger than 15 mm was used, even with a fluency as low as 10 Joules, I experienced adverse texture effects with my skin which included reddening, a scaly look, and small tannish dots. I experienced no such adverse texture effects with a 12 and 15 mm spot size.
However, it seems as if many technicians don’t want to use smaller spot sizes - is there a medical reason for this? Does anyone know why a larger spot size, despite technicians saying it’s safer, may’ve resulted in the adverse skin effects?
It would be great if someone knowledgeable about the topic could give me info, I'd really appreciate it