What does the clock-like symbols under plastic containers mean?
Under many of my food storage containers of plastic, there are circles with numbers and an arrow in the middle pointing at one of the numbers. What does these symbols mean?
Could it be recycling information? Plastic type? Production date? Serial number? Suitable for a special type of food?
Here is a picture of a food storage container of plastic from IKEA:
(click for full size)
Best Answer
This is the date the item was manufactured. The upper dial gives the year, the middle one, the month.
The bottom indicator could be a mold identifier, and in some cases, it might be a shift indicator (although this would typically be a clock going from 1 to 3, 4, or 6 depending on how shifts are allocated rather than the example showing 0 to 5).
See e.g. this manufacturer's datasheet on mold indicators: http://www.plastixs.com/pdfs/datecodeti.pdf
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Quick Answer about "What does the clock-like symbols under plastic containers mean?"
It's a manufacturing date stamp. It signifies the month in which the item was produced. Companies with mass production use it to track batches internally.What are the clock symbols on plastic containers?
Most commonly these "clock" symbols only indicate the mold used to form the part -- quality dept at the factory can then quickly track down which mold may need maintenance if faulty product is noticed.What do the symbols on plastic containers mean?
Most people know the little triangle symbol at the bottom of plastic bottles means 'recycle' but what they don't know is just because it has a triangle on the bottom, doesn't always mean it can be recycled. The numbers indicate the grade of plastic and can also tell you about the safety and uses of that item.What do the codes on the bottom of plastic containers indicate?
The number is a resin identification code, used to help recycling plants sort materials. Recyclable plastics are labeled with numbers 1-7 to tell workers what kind of plastic it is, and how it should be processed.What is the symbol for microwavable container?
Check the bottom of the container for a symbol. Microwave safe is usually a microwave with some wavy lines on it. If they container has a #5 on it, it is made from polypropylene, PP, so it is generally considered microwave safe.What those symbols on food storage containers really mean
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Answer 2
Top to bottom: Year, Month, Week. See D-M-E injection mold components catalog p157. If a problem turns up, the date markers will allow the investgating team to run down the batch.
Answer 3
At our plastic company, the last dial is the material source identifier. We source the injection molding pellets for HDPE from different manfacturers of comparable quality to keep them hungry and to keep us from having a supply crisis. 1 = company 1's resin, 2 = company 2', etc. This way you can trace a quality issue to the date and material source. sometimes it is a shift and sometimes it is a day of the week, just depends on the company.
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Images: Karolina Grabowska, Cadu Mello, Shiny Diamond, Martin Lopez