Hi Vicky, it looks like we are back in the bad smell business, tip-wise of course!! Plastic containers absorb smells for two reasons. Firstly, plastic is porous; secondly, fat, which is often where aromas are most concentrated, “sticks” to plastic unlike to glass or porcelain. I researched the problem and found varied options on how to sort it, so I set to test them in my kitchen to find the most effective one. The options I found include: 1. place the box upside down on grass in your garden overnight, 2. leave it open in your fridge for one hour; 3. fill the box with cold water and a bit of baking soda and let it sit for one hour; 4. microwave the container with water and lemon juice/vinegar; and 5. fill it with water, store it in your freezer and get rid of the resulting ice cube. I discarded this latter one from my benchmark as it is too complicated to be practical. Option 3 sounded the most interesting so tried it with baking soda and vinegar, another smell killer. I smudged tinned sardine oil on the inside of 6 boxes, put their lid on, and left them at room temperature an entire day. On the evening I washed all the boxes in hot, soapy water and here it was: a bad fishy smell in all my boxes! The experiment could start. I treated five boxes using each option, my control being the sixth box, left untouched. The results were compared using as a caliber my highly sensitive nostrils and those, somewhat less reliable, of my four-year old son Jules who happens to hate tinned sardines. And the winner was …. the baking soda (option 3), which was relatively quick, effortless and more effective than vinegar. The overnight grass option appeared to work too and required the least effort but I found my box chewed up by a fox so that disqualified it. The fridge option did not work that well, as the smell changed from fish to cheese (there was rather smelly camembert hidden somewhere in the fridge). The microwaving option worked but I rated it as a second best as not all plastics are microwave friendly. Remember that as for healthcare, prevention is always better than cure. To prevent smells from settling inside boxes, follow these two rules: 1. always wash your boxes in cold or lukewarm soapy water rather than hot, as heat favours plastic absorption of smelly molecules. 2. always store your boxes open, that way you won't trap humid air inside them. Last, for those interested in the bad smell topic, check out my previous tips on how to remove bad smells on a sponge, in the fridge, microwave, on in the house after cooking smelly food.