I used to take the temperatures on hair straighteners as a given but after this test with a infrared thermometer, I understand more about how my straighteners work.
The thermometer I used has an accuracy variance of + or - 2 degrees Celsius. I firstly checked the temperature of a travel straightener without heat settings. It got as high as 190 degrees which is too hot for my fine hair.
I bought my Berta straightener because apparently it's lowest setting is 120 degrees as seen on this dial. I turned it on and waited for the "ready to use" green light.
The temperature surged to 150 degrees.
But it dropped back to 122 degrees before the temperature crept up again.
I noticed a similar variance with the hotter settings. The highest at 210 degrees, set the temperature as high as 229 degrees. This was the maximum heat before dropping to 210 degrees.
Therefore the numbers on the dial shows the minimum temperature with a variance of up to 30 degrees. The straightener doesn't keep heat at a constant temperature. 120 degrees on the dial can be actually be 150 on the plates.
The test was important because my hair feels damaged at temperatures at 150 degrees and above. Heat control is a useful function but it's better to know the actual temperature, especially if you have hair that is prone to damage.