Rust promoter

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It's probably been discussed, but I can't find the thread. I'm looking for advice on promoting rust on mild steel to make new steel more closely match rusted steel. One of my sculptures uses weathered (well rusted) salvaged steel for most of it, and a few pieces of new 11GA mild steel scrap. I have removed the mill scale (60 grit flap discs) and have left the piece outside in the rain. I know that over time it will match pretty well, but the piece is in a show in 3 weeks. Is there a way I can accelerate the rusting process?

lin's picture


Hi Bob, I have used a mixture of vinegar, salt and hydrogen peroxide and sprayed it on to rust pieces. I don't have the formula handy, but if you e-mail me at and remind me, i'll research the exact formula. Lin

Bob Turan's picture

Rust Promoter


Thanks for the tip!
I did a little more digging on the site, and also found some other useful suggestions.

Bob 2-ran

Bob Turan's picture

Here are the proportions

Bob, that formula is 4 parts white vinegar, 1 part hydrogen peroxide
(3%) and 1/2 part of salt. I find it to work well and I like the fact that it is safer than most of the chemical patinas. Lin

Rich Waugh's picture

Ahhhhh...what's in a name?

I'm always amused when people say they like something like this because it isn't a "chemical" patina. The formula for this, expressed in scientific terms, would be 40 parts H2O + 2 parts CH3COOH + 10 parts H2O2 + 1 part NaCl.

Vinegar = 5% ethanoic (acetic) acid (CH3COOH)
Hydrogen peroxide = H2O2
Salt = Sodium Chloride (NaCl)

It is ALL chemicals!


Bob Turan's picture

You're right!

Just because those are common chemicals you might have under your sink somewhere, doesn't mean they are "safe"! You don't want to mix chlorine bleach with vinegar (acid) as it will produce chlorine gas, or mix it with ammonia which will produce chloramine gas, BOTH TOXIC!

I just posted Lin's comment to the blog here, so I could find the formula again. I had to go through archived emails to find it - at least now, I know where it is ;-)

I'm now trying to match some repairs I needed to make on a well traveled Corten sculpture. I am finding that deep brown/purple patina isn't easily matched by anything I have tried, so I may just wait for "Father Time" to blend it in.

Bob 2-ran.

Rich Waugh's picture

Ah yes, that most trusted of

Ah yes, that most trusted of panaceas, Tincture of Time. Almost always does the trick.


Chuck Girard's picture

Thanks Rich

Thanks Rich Thanks Rich,  The Chemical compound formula helped.  I think I'm getting better at the Mix.  6 applicaitons in two days. With 3 Coats of Penetrol.  Thanks again for the Tip..  Hyd. peroxide, white Vinigar and Salt    ChuckHarmony: Thanks Rich, The Chemical compound formula helped. I think I'm getting better at the Mix. 6 applicaitons in two days. With 3 Coats of Penetrol. Thanks again for the Tip.. Hyd. peroxide, white Vinigar and Salt Chuck

Will Jones's picture

Dangerous Chemicals

You'll like this, Rich
Will Jones

Rich Waugh's picture

I did like that Will,

I did like that Will, thanks! I'll be passing that along to a number of deserving victims...errrr, recipients.

My father, a career research chemist and Missouri-raised skeptic, used to answer people who started spouting "statistics" about the dangers of some "chemical" or another, with the following:

"Beware of the single most dangerous substance on Earth! Oxygen. That's right, oxygen - why, are you aware that oxygen is so dangerous that less than one part per trillion in the air you breathe is fatal within minutes!"  

When they appeared puzzled he would go on to tell them that there was incontrovertible scientific proof that this was so and they could check his facts with any competent medical authority anywhere.  In a few cases he would break down and tell them that of course it would be fatal since the human body needs about 280 million parts per billion in the air in order not to suffocate.  (GRIN)

Too many people these days, raised on ten-second sound bites from the TV talking heads, have absolutely no grasp of statistics or real science. Couch some patently absurd statement in "scientific" terms and they'll swallow almost anything - except evolution and global warming, of course.  They have never developed a capacity for critical thinking and regardless of the inherent absurdity of any pundit's position, just gulp down the Kool-Aid like good little sheep.  It would be amusing if it weren't so scary.  These are the same people who vote...

Thanks again for passing that on - I'm sorry Pop isn't still around to share that with, but others won't be so fortunate.  Tongue out

There are liars, damned liars and then statistics. - Benjamin Disraeli

Craig-K's picture


While I was away for a time there was a 'helpful' soul who put a jug of Muriatic Acid in my shop. I already knew that even a capped jug was not something to have indoors but I was surprised. One could look at the state of rust on iron about the room and track right to the jug.
It had been in there a couple months but it did give me some thoughts but I never got around to rigging up a container to give it more study. - I thought a large box with little circulation and just a dish of acid might do well.
I've meddled with brass with some electric etching and masking and acid and various approaches to tarnish to come up with interesting aged look.
Dangled some pieces inside a gallon jug with tablespoon of ammonia in the bottom does a nice blue. Vinegar gets a decent green.
Reminds me of another 'helpful' [expletive] who polished a tarnished piece of brass for me. Took over a month to get about as I wanted it.

gwynlaredogranger's picture

um you can use ferric

um you can use ferric nitrate. i make my own by dissolving iron into nitirc acid.this mixture (deoending on your nitric acid strength) can be diluted again to suit your tastes with distilled suprised no one else mentioned this.

Rich Waugh's picture

I think many of us steer

I think many of us steer away form recommending nitric acid compounds due to the inherent dangers of working with nitric. There are other agents such as hydrogen peroxide or household bleach that do the job just fine and are much less dangerous to handle and store.

Ferric nitrate does have its place though. It is my etchant of choice for silver, among other things. Less aggressive than straight nitric and therefore more controllable.


Jim Cotter's picture

I think this might be

I think this might be relevant to this discussion

I tried this stuff called crud cutter from Ace hardware
on some old cast iron and if you leave it out in the weather for about a week it looks like weathered bronze, I know you are looking for a red rust look but this stuff is something to see...

Def worth a try you can buy it online also

I'll try and post some pics of what it looks like

007BigBig's picture

Looking for more

I realize this is an old thread, but I am hoping to hear some advice on getting a more red and crusty look on steel.

I found this artist and absolutely love image number 4 of 10

Any educated guesses on creating the red oranges in the center sections and the purpley red crust that surrounds it?