Anyone have some non-destructive tricks to quickly and accurately (and cheaply) determine if rivets (1/4" diameter) installed in steel sheet metal are aluminum or mild steel?
Using a small diameter mag pickup didn't work because of the proximity of the sheet metal. Any chemicals that will react with either steel or aluminum but not both and give a pretty distinct reaction? (Alodine or cold bluing / parkerizing? ) Also, scratching or lightly sanding/filing the rivets is acceptable.