What is this?

[Fireguy]

13829most of the pan bottom is nice and smooth but some of it feels like 300ish grit sandpaper and have these little spots . I gave her a 3 hour soak in Apple cider vinegar and scrubbed with a very fine 3M pad for dishes. It doesn't seem to be taking it off well. Is it's OK to keep boiling with this? 13830 ps, this is the first time I try to post pictures so let's see if this works. Thanks in advance

[Michael Greer]

One of my friend likes to joke that "it says stain-less, not stain-proof steel". Either some mineral has attached itself to the metal, or some magical chemistry has etched INTO the metal. It's gonna be fine to boil with either way.

[Urban Sugarmaker]

My pan has this too. It's mineral deposit. After the season last year I soaked my pan with white vinegar and water overnight. The deposits came right off with a soft scrub brush. The pan came out looking like new again. Don't use an abrasive pad or steel wool. It will make it worse the next year.

[jpcole]

I had this in my pan this year also. I think it is the begining of "hot spots" from the sugar sand that collects at the bottom of the pan while you are boiling. If you can reverse direction of your pan that may help. I drained my pans and put about two inches of water in the pan with white vinegar, and brought it to a lite boil , than let it soak to loosen it up. Using pan cleaner is another option. Be careful while scrubbing your pan that you don't scratch it to bad, that may also give you hot spots. Rinse your pan real good and you should be good to go.

[BAP]

You have nitre build up on your pan. The nitre adheres to the pan over time. The more you have on it will decrease the boiling efficiency of the pan and can eventually lead to burnt spots on the pan.

[Super Sapper]

13841It is Niter on your pan. You will need to heat up the vinegar or pan acid (I use milk stone remover) and leave it sit longer. He is a picture of mine last year.

[Russell Lampron]

It is burned on nitre and a normal condition. If left uncleaned it will cause hot spots and you will be more likely to burn your pan. Use white vinegar, not apple cider vinegar to clean it. I use 2 gallons of vinegar and add water to 2" deep in my 2 x 2 syrup pan. I bring it to a boil like jpcole does and let it sit overnight. I drain it and pressure wash it the next day and it looks like new again. I never have and never will scrub it with anything.

If you want to continue to use it the way that it is increase the depth by 1/2" to 1" and watch very closely for making syrup in the middle of the pan to be less likely to scorch it.

[Fireguy]

Thanks everyone. It came out pretty decent after letting it sit longer. All I've made this year is dark syrup so I thought this may have been the issue. Some of it flaked off like in super sappers pic.