Ok, before the assembled crowd I do acknowledge my incipient leanings towards hoarding. And do acknowledge that when I was forgetful and didn't order new crush rings I have taken chances and after careful examination and consideration re-used the old one. Then recently on a ride/drop-by of my friend Greg's shop where I always examine the trash barrel for thrown away goodies, I was surprised to find at least 1 or 2 lbs of (I believe used) aluminum crush rings. I inquired - the trash barrel (actually a small cardboard box) is left out for metal collectors who routinely drop by and take away the metal.  - and was told the hoard came from the bike shop next door and nothing was known about them. SOooo, naturally I appropriated them and put them in a plastic bag and took them home. Now in my defense Greg is known to have thrown away tools which he didn't want to bother fixing and bike parts. For instance I recently have acquired an extensible wrench and a handle bar mounted rear view mirror such as used on K bikes. All with permission.

Now with the crush rings home, I washed and examined them and threw out any that looked marginal. Think there's still at least a lb of them left. What is the sense of the assembled intelligences on their use? I remember a discussion years ago on another website where certain types of washers/crush rings needed to be reheated and allowed to cool to remove work hardening. Does this apply to aluminum rings? Any issues to be considered?

As long as they are the correct size, then fit them and forget about them.

Increasing heat and then cooling down is what occurs to the washers naturally during the normal use of your moto via heat transfer from the engine and drive components.

Copper will aneal with heat

Aluminium wont

It just fractures the bond between the particles

Most aluminium heads after an overheat are treated wit suspicion as they tendv to weep - become pourous

When I remove a drain plug on any of my BMWs or our cars, I check the condition of the crush washer, whether aluminium or copper, and if it looks good enough, and has had only one use and isn't papery thin, I flip it over, torque to spec, and get another use out of it.

If you're worried about them being flat or have a small build-up of corrosion, wipe a fine file across them until the surface is all shiny.

- Skinflint Nerdhead III

Dai wrote:If you're worried about them being flat or have a small build-up of corrosion, wipe a fine file across them until the surface is all shiny.

- Skinflint Nerdhead III

That's sounds like a VIZ Top Tip from one of their readers.

charlie99 wrote:Copper will aneal with heat

Aluminium wont

It just fractures the bond between the particles

Most aluminium heads after an overheat are treated wit suspicion as they tendv to weep - become pourous

Not exactly true - some grades of aluminum can be annealed. I worked in a jobbing foundry for 34 years. One product we made was disposable aluminum water pump casings used in forest fire fighting - Grade A356 if I remember correctly. Part of the production process was annealing them prior to machining. 
Hard to say what grade our crush washers are made of, but worth a try.
 https://orangealuminum.com/blog/annealing-aluminum-explained-what-it-is-and-how-it-works/

That link and any discussion about it must surely be an entirely different metal, after all, it's not even spelt the same!