Why we do not store liquids in plastic baggies.

And the results are in.....It was the iodine that diffused in our Diffusion in a Baggie Lab and not the cornstarch! We know this because the color of the solution in the baggie turned black! Had the cornstarch diffused through the baggie, the solution in the beaker would have turned black and it didn't! The bag then is semi-permeable, allowing the iodine to pass through but not the cornstarch. I guess this is why we do not store liquids in plastic baggies.