Yep, I ruined a good EAB cylinder head by leaving it in vinegar too long. Works great on steel though...
Have done a few really rusty steel wheels, hit them with the pressure washer after soaking and they look like new. You must dry the parts right away though, or they flash rust.

 

I posted this question in another thread but did not get a lot of feedback. I have a marine steering wheel that I need to restore (I volunteer in the wooden boat shop at a maritime museum). The wheel has typical cracks from "exploding" rust. I know that I need to get the rust out and halted. I restored a Banjo wheel in the past, however the rust on the rim was not that significant. I typically media blast parts however not a good option in this case. I have also used the diluted muriatic process on nuts and bolts. Has anyone gone thru this process? Your thoughts?

 

I can't see molasses eating away cast iron that fast? The block must have been pitted already and the molasses ate the rust away leaving the pits. Any rust removal method would have done that tho
Concentration of acid in molasses can't be that high.

Heck molasses is all natural so just dump it and wash it way. As for the rust left over, ferrous iron is the most abundant mineral in the ground, I'm sure adding a little more won't hurt

 

Bill, can you post a pic of your wheel? Trying to visualize where your rust is.......

 

The acid doesn't seem to affect the rough casting surfaces, just the machined ones. Not sure why. I tossed that head that I ruined....or I'd take a pic.

 

I think no one would say milk is a hazardous material. It can be.
Case in Point.....A road tanker overturned spilling say 2000 gallons of milk has the potential to be a mini environmental disaster. A trailer full of eggs even worse.

So that volume of molasses IMHO could pose a major problem to properly dispose. Add all the iron gunk maybe even lead or mercury and what ever unknown substances it draws or converts out of the iron or left over paint and you could have a real problem.

10 gallons or so... no big deal. A couple of hundred gallons...big difference.

Another thing is, there is no free pass. Who knows what this stuff really does to the metal. It may be fine now but what about 50 years from now? It's an acid treatment and acid attacks the metal. It does in a few days what would take years of natural oxidation or rusting. The reason this stuff "works" is it goes through the oxidation "rust" to get to the parent metal. In porous metal like cast iron it penetrates and attacks the iron deep inside the metal. That's why a finely machined iron part like a head or block surface comes out looking like a deck gun from the Santa Maria.

I think this stuff takes something away from the part. It goes through the layer of oxidation very fast to chew on the parent metal. That black gunk you scrub off is not all "rust". In my accidental experiments, A viable but rusty sheet metal part came out looking like a million dollars, a short time later it was a crumbly brittle POS.
For stuff like pulleys brackets this stuff may be fine. For cabs bodies and frames, I would not.

 

Scott,
I will try to take a pic the next day that I volunteer.
Bill

 

What i've always done is knock the loose rush down with a wirebrush on a drill the use Eastwood's rust encapsulator. It seems to work well, but I also realize I don't know how it'd be able to tell if it didn't.