When you are checking shims and have a bunch out of spec its imperative that you don't mix up the buckets and shims from where they came from. I tend to find that ice cube trays work awesome for this very thing. Here is a pic of how I do them. It also works for other items as well if you need to keep small nuts and bolts separated.

 

How long does it take to thaw them before they're ready for use?

 

That’s just how I like my shims, on the rocks.

seriously, that’s a really good idea. I go through way too many ziplock bags.

 

I usually start to thaw them out the day before use.

 

I've used egg cartons, but if an extra ice try is handy, that would work too.