My instructor said dish soap or soapy water. I'm pretty sure
that would apply to both oxy and acetylene tanks.

At first I spaced out and thought you meant you were cutting a tank.
One of the first things this guy said is "NEVER cut a tank".
"Your friends will ask you to. NEVER cut a tank!" He showed us a picture
of a welders body on the opposite side of the road from the tank.

Sux, cause I have one I'd like to cut. I suppose I could fill it
with water or inert gas, whatever that is. Or use a sawsall.

Sorry about the digression...

Eeeek!
That's a scary story.

there's a thread on another group about the how-tos of cutting a tank. the idea being to use it to make a BBQ pit. Then, one guy cuts to the chase and says to just buy a new, unfilled tank from a supply house. Doh!

Thanks for the plain old soap tidbit. I guess that and some of the semi abrasive cleansing pads will do just fine. Or I'll just have to pratice batting my lashes at strong, manly types...