How long do you have to heat (dehydrate) filament

I have previously posted how to convert a Sanlu dehydrator. I want to explain how I use it to improve print quality.

I set my dehydrators to low limit 49C high limit 50C, low limit 16%RH and high limit 17%RH. Both limits must be out for the heater to heat (<49C and >17%RH).

When you put a new roll into the dehydrator the first thing you notice is the RH% goes up as the TempC goes up as the moisture leaves the plastic. At some time you will notice the TempC is significantly lower than 49C and the %RH is <17%RH. This is the point at which you can use the filament having removed the moisture.

I have some plastics that come in at 24%RH and are printable, the finish improves when I move the moisture down. I have found this takes from 2 to 4 days. Sunlu takes 4 days and the finish significantly benefits from from waiting

This is set and forget. The temp stays high until RH% hits required level then drops down to a much lower maintenance temp.