You could probably spend a fortune paying a test house.
My guess is that If you test it (empty) in the most powerful microwave you can find and it doesn't get too warm. You could say it was ok.
This assumes you are producing a consistent product, you should also test a statistically significant sample... (I always think 30 is a damn fine number...but I'm sure that 73% of statisticians would dispute this 25% of the time )
Presumably you have already searched for standards?
To my mind it is about exercising 'due diligence' eg... record all your testing and maybe take regular production samples and do a re-check.
I expect I will get slated by some health and safety guy who will throw his hands up in horror and shake his head. But why should your (cheap) tests be less valid than expensive ones?
Much of EMC and CE testing in the electronics business is done by 'self certification'...hmmm that's another nice phrase to throw into the file.
Good luck
Del
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I am no expert, but along wth ensuring it does not explode, I believe it is also necessary to proove that no (or minimal) chemicals will leach into the food from the container during cooking.
Test as another posted said with an empty container of yours in a powerful microwave oven, but make sure that you also have another container, filled with water nearby in the oven at the same time as some Microwave ovens do not like it if little or no energy gets used.
If your sample can be easily picked up after 5 minutes (basically cold) then you do not have a problem.
Check all new batches in the same way.
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"What others say about you reveals more about them, than it does you." Anon.
Try ....here. That should start you out. There is a surprisingly large amount of reference material found by a Google search of 'microwave safe standards'.
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Glazed ceramics will also deteriorate in domestic use and eventually heat up seriously in microwave ovens due to penetration of moisture and dishwasher chemical through sagger marks and other holes in the glaze.The glaze often crazes and the effect cumulates.