Clean is not food grade, and food grade is not clean
On this page11
The first direction
A used bucket, scrubbed, reused for rice. It is clean. Whether the resin was compounded for food contact is a separate fact that washing cannot change.
And a polyolefin absorbs what it holds
Which is the physical half of the same problem. A bucket that held solvent, detergent or sealant has taken some of it into the wall, and it comes back out into whatever is stored next.
So a free bucket is rarely a bargain
The commonest advice in this category is to get buckets free from a bakery or a restaurant. Those held food, which answers the absorption question, and they still may not be a resin compounded for food contact.
Ask the source what was in it
Which is the practical version. A bucket that held frosting is a different proposition from one that held floor finish, regardless of how either looks now.
The second direction
A genuinely food-grade container that held something strongly flavoured. The resin is compliant and the rice will taste of pickles, because absorption is physics rather than compliance.
Which has no cleaning solution
Odour absorbed into a polyolefin wall does not wash out. Sunlight, baking soda and time are the usual folk remedies and none of them reliably works.
Glass does not have this problem
45 glass containers on this shelf. Inert, non-absorbing, and the reason glass has been the long-term food store for two centuries.
And it has the other problems instead
Heavy, breakable, and in an emergency a broken container is worse than a tainted one. That is the trade and it is why both materials persist.
The liner sidesteps both
A mylar liner inside a bucket means the food never touches the bucket, which is why the craft uses them. We do not stock them, which is worth repeating here rather than only on the first page.
What to ask a supplier
Which resin, which additives, and do you hold a food-contact statement for it. Three questions with real answers, and a supplier who cannot answer them is telling you something.