Topless & Cold ...

Worked out most of the kinks for testing the tumblers when used with a cold fluid ... beer!

Used a Zojirushi pump type thermos with crushed ice to get the water down to 32 degrees.  The pump filtered the ice out of the fluid as the tumblers were filled one right after the other.  All tumblers were at room temp (75 degrees) prior to being filled.  To prevent stratification of the temps, a bamboo skewer, long enough to reach the bottom of the tumblers, was used to stir the water one minute before the temp was recorded.  With temps being measured every 15 minutes, that process kept the temps within one degree from top to bottom.

Since beer was the fluid being simulated, it was only fair to add in one of my favorite beer glasses:



Here are the results:



The first temps were recorded at the five minute point.  Good thing my favorite beer glasses stay in the freezer, 'cuz there was a ten degree jump in the fluid temp in the first five minutes.  The generic tumbler saw a two degree jump and the other two saw only a negligible jump in temp.  There was only a 43 degree difference between the fluid and the tumblers, so that makes sense ... the hot test saw three times that difference.

The line up of mugs, based on ability to keep fluids cold, matches the line up from the hot fluid test ... as would be expected.  The Zojirushi and the Yeti are both very efficient at keeping your beer cold ... in fact, it looks like the beer will go flat before its too warm to enjoy drinking.

The only conclusion I can see is that if you keep your glasses frozen, then any of the four tumblers will work for beer.  For large Margaritas, you might want to move up to one of the branded tumblers.