RTIC and other highly insulated tumbler companies make a big noise about how long their cups and coolers keep ice. And they do keep ice for a looooong time. If you're in Alabama, RTICs and the like are nice to have.
But I'm back in the Great Northwet now. Up here, I want to know about keeping drinks warm.
I poured boiling water over tea bags and let them steep 3 minutes.
The temperatures shown are after 3 minutes of sitting uncovered. The RTIC is on the far right.
I added milk (because that's how I like my tea) and covered them up.
Two hours later (I forgot I was running an experiment), these were the temperatures.
I drank the tea in the Copco travel mug. It was a little cool but it's a sin to waste tea.
About 3.5 hours into this test we get these results.
I drank the tea in the RTIC.
According to experts, the perfect temperature at which to drink tea is 140 degrees Fahrenheit (all is lost after 112 degrees). I'm going to guess the tea in the RTIC would have been at the optimal temperature about 30-40 minutes earlier.
I'm calling "drinkably warm" at 3 hours. You could probably extend this time if you put a towel or something over the lid.
Just so in case you were wondering, I did drink the tea from the thermos later that afternoon. Because it's a sin to waste tea. It was about 65 fluid ounces of tea.
I don't think I've had so much caffeine in one day since 1998. It was rather painful.