Always used new hardware and flange nuts for expedient assembly of my pump restorations but couldn't bring myself to toss a 80 year old large bolt and heavy oversized nut. Ended up with a bunch of large plastic nut containers full of brass machine screws, 5/16 up bolts and nuts, and miscellaneous do das left over from 20 years of doing gas pumps.

Don't have a media tumbler and sold my cabinet blaster so I used the common household method:
couple gals of white vinegar
Simple Green
Kroil Gal
Optional Gibbs oil

Fill each tub with straight vinegar and soaked for couple days.
Poured off vinegar and flushed each tub with scalding water and Simple Green
Poured off water and dumped content into an old towel and shake to dry
Dried out plastic tubs, returned contents and added about two ounces of Kroil and shake, coating the bolts. Let set for 24 hrs. and again dump on same towel to wipe excess and return to tubs. Optional: spray gibbs oil on them .

Process will remove rust and leave hardware with darker clean oil finish.
Vinegar will turn brass the darker red color so be advised.

Nice to use on early stuff where the nuts and bolts show or the internal mech is displayed. All probably knew this but made me happier to not throw them away.
And I hate punching them through cardboard so my blaster will clean them.
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larry ivy