'21 Bell New York Telephone Co. Flange Sign BIN

[magicbrain]

I purchased this '21 Bell New York Telephone Co. Flange Sign with a BIN price of $165.00 + $10.00 shipping.
Having just received it, I don't know if I got a deal or not - it is in decent shape with one ding, but I took a gamble as it is covered with some kind of film which may or may not come off.
I will try cleaning it using the method posted by Sargeguy
https://tinyurl.com/y8eyvz9z

[Key2871]

I once bought a transatlantic cable sign, it was grubby and a little bent. I took it home gave it a good cleaning, and then used semichome polish and it looked great.
So that's what I would try, doing a small area see if it comes off. It could just be cigarette smoke stained, that's what it looks like

[magicbrain]

It could just be cigarette smoke stained, that's what it looks like

No, I wish - now that I have it in my hands, it's something else on there almost like hard water stains - this sign clearly spent years/decades outside somewhere - a New York City street maybe.

[Key2871]

Vinegar and baking soda is good for cleaning hard water stains and grub. It's cheaper too.

[Doug Rose]

I used Citrix Stripper and fine steel wool on an old NET sign that looked just like yours. Porcelain will not be damaged. Try on the side you do not plan on displaying and do a small area to test. My sign came back looking like new.....good luck....Doug

[Sargeguy]

That is one of the harder stains to clean.  The stain embeds itself in pores and cracks in the porcelain.  I recommend soaking in distilled water for a start. That will loosen the bond.