passatdoc
Well-known member
Now and then you will see articles, mainly plastics, labeled as "upper rack dishwasher safe". Certainly, if a dishwasher has an exposed heating element and in particular if heated dry is used (assuming it's still even an option), a plastic utensil will be exposed to greater heat on the lower rack and may warp or melt.
However, some newer dishwashers do not have exposed heating elements, and there is no "heated dry" option (vs. "energy saver dry") any longer. My eight year old Bosch has a concealed heating element and drying occurs because water condenses on the steel tub sides, pulling water off the dishes and plates....the heating element does not activate during the drying phase.
So, in this setting, would the temperature experienced by a plastic utensil really vary that much between top and lower racks? It seems that the temperature would be rather uniform throughout the tub.
I have had some plastics that warped...usually large, thin-walled plastic containers from Costco (nuts, candy, popcorn, etc.) that I was trying to recycle for other uses. However, the warping occurs regardless of rack level and most likely signifies that this light plastics were never intended for a 140 F final rinse!! (in fact they probably were never intended for dishwasher use, period!!).
However, if you only count items that were meant to be reusable, like the Glad food storage containers you get at the market (good for food storage or freezing), or lightweight plastics like the bins on a coffee grinder (upper holds the beans, lower holds the ground coffee), I have never had a warping issue in this dishwasher. The previous dishwasher was a MOL GE Potscrubber (good riddance to bad rubbish) and I always used "Energy Saver Dry" (i.e. exposed heating element off), though had I used the "Energy Hog Dry", I suppose I might have seen some warping.
I recently bought a Panasonic rice cooker and the glass lid--which has a plastic rim and center knob--was marked "top rack safe only". It's gone through a dozen or more washes so far, sometimes upper and sometimes lower rack, without any problems.
Your take?
However, some newer dishwashers do not have exposed heating elements, and there is no "heated dry" option (vs. "energy saver dry") any longer. My eight year old Bosch has a concealed heating element and drying occurs because water condenses on the steel tub sides, pulling water off the dishes and plates....the heating element does not activate during the drying phase.
So, in this setting, would the temperature experienced by a plastic utensil really vary that much between top and lower racks? It seems that the temperature would be rather uniform throughout the tub.
I have had some plastics that warped...usually large, thin-walled plastic containers from Costco (nuts, candy, popcorn, etc.) that I was trying to recycle for other uses. However, the warping occurs regardless of rack level and most likely signifies that this light plastics were never intended for a 140 F final rinse!! (in fact they probably were never intended for dishwasher use, period!!).
However, if you only count items that were meant to be reusable, like the Glad food storage containers you get at the market (good for food storage or freezing), or lightweight plastics like the bins on a coffee grinder (upper holds the beans, lower holds the ground coffee), I have never had a warping issue in this dishwasher. The previous dishwasher was a MOL GE Potscrubber (good riddance to bad rubbish) and I always used "Energy Saver Dry" (i.e. exposed heating element off), though had I used the "Energy Hog Dry", I suppose I might have seen some warping.
I recently bought a Panasonic rice cooker and the glass lid--which has a plastic rim and center knob--was marked "top rack safe only". It's gone through a dozen or more washes so far, sometimes upper and sometimes lower rack, without any problems.
Your take?
