Field Locations and Conditions:
Over the past 2 months, I have used the Primus Lunch Jug (hereafter, lunch jug) on several day hikes as well as one bike ride. Some of the hikes included part of the Carolina Foothills Trail (South Carolina), part of the Bartram Trail in Tuskegee National Forest (Alabama), Gulf Islands National Sea Shore (FL), and a series of private trails in Maryland. Elevations traveled ranged from sea level to 3000 ft (914 m). Temperatures ranged from approximately 40 F (4 C) with snow flurries, to 80 F (26 C) and sunny.
Before heading out in the field, I conducted a series of tests at home to see how long the contents would stay hot in a controlled setting. My rationale for this was due to Primus' reported findings on their retail box. Their testing was conducted with an ambient temperature of 65 F (18 C). I was curious to see if there were any differences between their results and those produced from a colder and more probable Fall/ Winter hiking temperature scenario of 38 F (3 C). In all tests, I followed the manufacturer's recommendation to prime the lunch jug by adding hot water for 5 minutes, then draining the hot water and adding the desired contents. In the first test series, the contents were 190 F (88 C) water. The lunch jug was then placed in the refrigerator (38 F/ 3 C) and the temperature was checked hourly with a digital thermometer. At 8 hours, the contents were 100 F (38 C) which was approximately 30 F (1 C) less than what was reported in the graph on the box. I also investigated the temperature change over a nine hour time period where the lunch jug was only opened at the end of the time period. In this test the contents were 200 F (93 C) water. The lunch jug was then placed in the refrigerator (38 F/ 3 C) and allowed to sit unopened for 9 hours. At 9 hours, the contents were 101 F (38 C) which was approximately 20 F (7 C) less than what was reported in the graph on the box and 12 F (11 C) less than the temperature recorded at nine hours in the hourly test. I concluded that the lunch jug does keep its content's warm in a 'cold' environment however, not as warm as the box claims. Again, this is more than likely due to the differenced in ambient temperatures used to test the lunch jug's heat retention.
During cold hike testing (<60 F/ 15 C), I packed tea and chunky soups into the lunch jug. Before hiking, I followed the manufacturer's recommendation to prime the lunch jug by adding hot water for 5 minutes, then draining the hot water and adding the desired contents. I was unable to do this on one hike and did notice that my tea did not stay warm nearly as long as it had on other hikes. Also of note, there was no heat transfer noted on the outside of the lunch jug. All of the warmer hikes (>60 F/ 15 C) were impromptu and I merely filled the lunch jug with water from my refrigerator's cold-water reservoir. The lunch jug did not disappoint and kept my drink cold throughout the hikes.
The lunch jug packed nicely into my child carrier and lumbar pack, as well as a small
daypack . The exterior coating did enhance the lunch jug's 'traction' and helped keep it in my hands more than other beverage containers I've hiked with. It also held up well on the few occasions where I tripped and it went airborne. The wide mouth made it easy to fill with liquids and chunky soups as well as consuming them. Cleaning the lunch jug at the end of the day was very easy. The wide mouth allowed easy access for wash cloth or a bottle brush.
Now for the lid. I had concerns about the lid prior to testing (see IR above). Even though the lunch jug took a couple of tough falls, the lid held up and did not crack or break, which was an initial concern I had. I did notice that the grips on the lid did not provide as much traction for my hand when unscrewing and screwing in the lid. The traction was notably worse when I tried to open or close the lunch jug with gloves on. I wasn't happy about having to take my gloves off on the cold trips just so I could get a drink. There was also a noticeable amount of flex in the lid. I also noticed that it was fairly easy to screw the lid on incorrectly, almost cross threading the manufacturer's threads. Unscrewing it when this would happen was usually not as easily done. Even when properly screwed on, the lid seemed to have two different stop points. The first stop seemed to be secure however, there usually was a small amount of leakage. The second stop was usually ¼ turn past the first stop and held the contents securely. This really bothered me on the cold hikes when I was trying to screw the lid back on with gloves on.
Even with the lid's quarks, I think the lunch jug does its job done and it kept this hiker warm on the inside during the cold hikes as well as providing a refreshing cold drink on the warmer hikes.
- Insulating capability for both hot and cold contents
- Packability for day trips
- Wide mouth for easy filling
- Traction on the exterior of the jug
- Lid (lack of traction, sealing quirkiness)