The technical specifications state that to polymerise Plastisol ink takes 2 minutes at 160°C. On your blog I read “a distance of 6-7 cm is correct: it takes quite a long time (approximately 15-20 seconds) and it reduces the risk of burning the fabric”. Why is there this difference?

I can confirm that 2 minutes at 160°C is correct for polymerising plastisol ink.
The 6-7 cm distance for 20 seconds was probably referring to the partial drying time between one colour and another, carried out using a flash dryer.