I picked this sign up a while back and finally got around to cleaning it. I tried all the recommended products but nothing would touch the contamination on its finish. As a last resort I applied muriatic acid for about 15 to 20 seconds and rinsed/dried and repeated as necessary and that did the trick. As you can see, the red had a lot of fading so about an hour of "stand on it" buffing (someone on here suggested that), it looks much better. This was by far the toughest one I have had to clean so far.



Before


After

Cleaned up really nice!

When using muriatic acid, do you need to dilute it with water? 10-1 or something? When youre finished do you have to neutralize the piece with baking soda or anything, or just rinse with water? I have a couple signs i would like to try it on this weekend. thanks

Is there a thread on here anywhere that goes through the proper cleaning techniques for old signs? And for how to deal with rust on cans for instance.

Also, has anybody tried tannic acid to remove rust? Its in tea and coffee and i hear it works well to remove rust.

Looks SUPER!

Anyone ever try Efferdent mixed with water to a pasty state and use it on stained porcelain? It will work!

I have done this many times with Muriatic acid and it works great. All I do is wash it off with a water hose and it breaks the acid down and then just wipe it down it with a dry towel. Then put a coat of wax on it because it will rust again if left exposed, just a hint dont put the acid on in direct sunlight because it seems to burn the finish a bit

Where can you buy Muriatic acid?

Home Depot

I used the acid at 100% and just rinsed well with water. I got the acid at Tractor Supply.

Anywhere you can get Pool & Hot Tub Chemicals.
To neutralize, use Baking Soda mixed in water, before pouring down the drain.
Use any ACID in a WELL VENTILATED AREA & ALWAYS wear EYE & SKIN PROTECTION.
Keep containers of ACID covered, fumes will enhance Rust.

the product you buy at pool companies is 3 times as strong as what you buy at hardware stores,so keep that in mind and adjust the time you leave it on.