Why are some items only ‘top rack dishwasher safe’? 62 viewsJune 9, 2021 Question31.48K June 9, 2021 9 Answers What is the difference between the top and bottom rack? In: Other fierohink commented June 9, 2021 The proximity to the giant heating element at the bottom of the dishwasher. When the dishwasher goes into its dry cycle, that heating element gets really really hot, the top rack doesn’t get nearly as hot as the bottom rack. Picture sitting right next a fire place versus across the room on the couch. Sure the fireplace warms the whole room, but sitting on the hearth is WAY hotter. So if you’re made out of plastic that could warp or deform from high heat, you should stay on the top rack. Taleeya commented June 9, 2021 The top rack water has a slightly lower temperature – so some things (like plastic items) are less likely to melt/warp dm80x86 commented June 9, 2021 Most dishwashers have a heating element under the bottom rack for heating the water and drying; top rack items can be damaged (melted/warped) by the extra heat. blipsman commented June 9, 2021 The heating element for drying is at the bottom of the dishwasher, and due to its proximity can melt plastics. markobie commented June 9, 2021 Modern higher cost dishwashers place the heating element in the water pump and super-heat the water (which also sanitizes) during final rinse so that moisture will dissipate. Meltable dishes are safe top or bottom. OStigger commented June 9, 2021 A lot of plastics used in food containers are from the polyolefin family of polymers, polyethylene (HDPE) and polypropylene (PP), which get soft and begin to deform at 140F and 180F, respectively. The heating element in many dishwashers is at the bottom, so it’s more likely that deformation of those plastics will occur the closer they are to it. Most plastic containers are made from these plastics because they A) are food safe (aka generally unreactive to the compounds found in food and do not leech chemicals or break down when exposed to food) and B) are cheap as hell. For example the clear parts of Rubbermaid containers are usually HDPE and the lids are usually PP. Nalgene bottles are usually some specialized form of HDPE. gameofbananas commented June 9, 2021 Bottom rack gets too hot. Some items can melt if it’s too hot but not melt if it warm. Hence those items can go in top rack and not bottom rack. tsohgmai commented June 9, 2021 Can I use this thread to ask why my dishes are left with water/soap spots after my dishwasher is finished? Is it the detergent I’m using? BlueFishDesign commented June 9, 2021 There is a difference where you put your dishes in the diswasher? Had no idea 0 Answers ActiveVotedNewestOldest Register or Login Other Questions You Might Be Interested In: If Vaccines contain the same germs(bacteria/virus) that cause the disease, what does vaccination hel...What is the academic reasoning behind believing we live in a simulation?Why does video chat (skype, etc.) appear to be so low in quality compared to video streaming (netfli...What’s the difference between first, second, and third countries?How does 8D music work?Why the light of stars outside the solar system don't/barely make us warmer.