I came across some information somewhere about using ketchup as a cleaning agent... I decided to try it out on a small section of one of my very dirty stoves. I applied some ketchup and after twenty minutes, I scrubbed it off with a soft brush. Has anyone had a similar experience? Is this simple and inexpensive method safe for brass?
I won't say whether ketchup is safe for brass. It's the vinegar in ketchup that does the work. I use 1 cup of flour, 1 cup of vinegar, and 1 cup of fine salt, which I mix and apply. With both methods, it's important to wash well with soapy water to remove any residue from the above.
I'd welcome thoughts from somebody who knows the science. From my understanding, if any substance is corrosive enough to eat brass oxide, it will also be capable of stripping the zinc from the sound brass. Open to correction.
Vinegar, which is an acid (acetic acid), can be neutralized using a base. The most common and effective method at home is to use baking soda (sodium bicarbonate). Here are the most common ways to neutralize vinegar: Baking soda: When baking soda comes into contact with vinegar, an effervescent chemical reaction occurs, converting the acid into water
I am no chemist, or cook for that matter, but the active ingredients in ketchup as a cleaner of brass are acetic acid (vinegar) and citric and malic acid (tomatoes). All blended into a sugary paste which has good stay put properties. There are posts on this site where Kerophile shares the secret of his GSR ( George's Stove Restorer), a blend of starch wallpaper adhesive and citric acid, which performs a similar function without the food waste. I have also used a quick dab of rust remover like Jenolite (active ingredient: phosphoric acid) to remove a build up of blackened tarnish, quickly wiping away and neutralising it before it dissolves the zinc out of the brass.
The 'before it dissolves the zinc' has always seemed a bit iffy to me, what's the likelihood of unwittingly significantly weakening the brass before the change is detectable to the eye? In other words can damage be done before things turn pink?
Baking soda turns the acid to carbon dioxide gas, water, and salt I believe I prefer soap and dislike removing patina
@Blackdog Not intending to suggest it would dissolve all the zinc, but pinkening of the brass can be achieved after not very long at all. You may not notice it under pickling grime and certainly not under a layer of opaque ketchup paste. I make no comment as to whether or not it is harmful to the item, but I find it aesthetically unpleasant and, as the zinc was there for a reason, I would prefer it to stay that way.
Thanks to everyone for your various opinions. Indeed, I checked the ingredients in the ketchup, and it contains two fairly harsh ingredients. Most of the stoves I buy come from flea markets and junkyards. Some are so caked in grime that washing them with detergents doesn’t do anything. They often require various soldering repairs, so cleaning is a necessity. In such cases, I usually used wet sandpaper, working with progressively finer grits (600–1000). Of course, there are beautifully patinated pieces (like this No. 51) that just need a quick wipe with a cloth and don’t require any cleaning. I think I’ll carefully try one of the methods recommended here. I think that with a little practice, they won’t damage the surface the way abrasive materials do.
That's my concern with most cleaning methods. Be it acids stripping the zinc, polish containing ammonia or other abrasive methods physically thinning the brass, we can't really be sure when we are affecting the structural integrity of the pressure vessel.
