A couple of days ago I asked for ideas on cleaning my stainless steel preserving pan which had a heavily 'crusted' base after making chutney.
I tried both the soaking in salt, and the vinegar suggestions with no success.
At bedtime last night I put in two dishwasher tablets, covered in boiling water, and left to steep.
This morning I was able to scrape away a lot of the carbon (?) with the back of a plastic washing up brush. Then I put un two more tablets, covered with boiling water (just) and boiled for about 10 minutes.
Eureka - every bit came away, leaving the pan like new.
I washed it thoroughly in hot water and Fairy liquid to make sure nothing remained.
Nothing left, and no scratches on my pan.
Thank you for those who suggested this solution. I have emailed it to all my preserve-making friends, and to those who - like me - occasionally forget they have something cooking on the hob when busy with other things.
It is horrid but it works. Ladies' hair colouring goo. Mix it in the pan top up with hot water to cover burned parts and leave it alone for a couple of days, or cook rhubarb in pan anything acidic. I did this when stainless pan got encrusted with burned pop corn. Worked a treat.