Does resin or hardener settle in the can over long periods of storage? There are no instructions to shake or stir before use, but I am still wondering if the contents of either can settle or separate such that the first part of the can might perform differently than the last?
So, is there any reason to shake or stir cans?
If the period of time is long, I WOULD stir it before use.
If we talk about epoxies: Resins are chemicaly cleaner, but hardeners are charged of components and any of them could settle by density or other reason.
With the polyester, it’s convenient if the cobalt is added, as its density is high.
In any case, I would do a proper test before laminating a part.
Yes they generally do settle
With epoxy resins, they might crystallise as well. Heating them (unscrew the lid slightly) in a bath of hot water, then give it a good shake (you did re-screw the lid, did you?) to dissolve the Crystals in the upper part of the can usually solves it.
And indeed: when in doubt, mix.
All responses appreciated. I will more closely inspect and stir my next can(s).