The same lid system on two different bodies produces two genuinely different tools, and each is better at things the other does badly.
What Glass Does Better
It goes in an oven, which plastic does not. Cooking and storing in the same vessel removes a washing-up step and a transfer.
It does not stain or absorb odour. Tomato sauce leaves no trace, and last week’s curry does not haunt this week’s rice.
It is easier to judge as clean, since nothing is absorbed into the surface, and it does not scratch the way plastic does.
What Plastic Does Better
- Weight, which matters in a lunch bag every single day
- Not breaking when dropped, which matters with children
- Cheaper, so a full set is affordable
- Stacks and nests more compactly
- No thermal shock risk
Ranges carrying both bodies under one lid system, of the kind at mysnapware.com, allow a household to use each where it belongs rather than committing to one.
The Weight Difference Is Not Trivial
A glass container full of lunch is noticeably heavier than a plastic one, and a week of carrying it makes the point.
For anyone commuting on foot or by bicycle, or for a child’s lunchbox, that alone settles the question.
Glass Breaks
Tempered glass is considerably stronger than ordinary glass and it is not unbreakable.
When it does fail it granulates rather than splintering into shards, which is a genuine safety property. It still means glass fragments in a kitchen, and any food near a breakage should be discarded rather than picked over.
Glass is a poor choice for a child’s lunch bag and for anywhere it will be dropped on tile.
Thermal Shock
The specific risk with glass. A rapid temperature change can crack it: a dish straight from the freezer into a hot oven, or a hot dish onto a cold wet worktop.
Let glass come toward room temperature before a big change, and set hot dishes on a dry trivet rather than a cold surface.
Plastic and Heat
Polypropylene handles microwaves and top-rack dishwashers, and it should not go in an oven or under a grill.
Prolonged high heat is what warps a plastic container, and a warped rim no longer seals.
The Practical Answer
Glass for the fridge, the oven and anything strongly coloured. Plastic for lunches, travel and anything carried.
Same Lids, Different Jobs
Which is the argument for a system rather than a mixture.