Rust Removal -
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post #1 of 30 Old 07-14-2012, 06:29 AM Thread Starter
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Rust Removal

as jeep owners rust is a big part of our life.

any of you chem dudes (not the snort chem dudes) ever heard of this rust removal process.

might be an old wife's tail, but i know sometimes working on an old vehicle, you need to save the part as there just are not any other replacement parts out there.
"> I use molasses in solution, 5 parts water to 1 part molasses, although I've seen folks go as high as 10 to 1. Immerse the rusted part in this goo and forget about it for a while. It's not fast; surface rust might take a week, while deep rust might go 2 or 3 weeks. But I don't have to come up with a safe way to dispose of nasty chemicals, either. My well is no further than a couple hundred feet from my septic system, so anything I pour into the ground has a shot at working its way into my drinking water. Normally, we store the nasties until the town has a hazmat disposal day, typically once a year.
> Molasses contains something called a chelating agent, the chemistry behind which I don't claim to understand. It binds to the iron oxide, but it won't attack the rest of the metal that isn't oxidized. This process, like the others, won't make metal grow back, so if the surface was deeply pitted, it will come out deeply pitted, but a very rust-free deeply pitted. The surface will be clean, bare metal, so when you pull your parts out, be prepared to paint them, oil them, or come up with some kind of protective coating, or they'll oxidize very quickly again, sometimes in minutes if the conditions are right.
> I've got a small vat of this going in my basement right now with a number of tools soaking in it, and more in the waits.

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post #2 of 30 Old 07-14-2012, 06:40 AM
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I read about the molasses trick when I researched rust removal techniques. It sounds interesting, but messy and smelly.

I eventually found an off-the-shelf product called Phosphoric Prep & Etch (Home Depot - $16). Just spray it on, let it sit overnight, then wire-wheel and clean. The acid neutralizes the rust.

Here are a few examples of parts I used P&E on. I don't represent them in any way. I'm just a satisfied customer.

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post #3 of 30 Old 07-14-2012, 06:57 AM
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sounds alot like electrolytic rust removal heres a link to a conversation from another forum. i learned how to do it reading it
it works very well and if your careful you can keep it a relitivly safe and non hazardous process
ive used prep and etch and it works well for what it does. its really useful for removing surface rust.

one reason i opted to use electrolysis is its alot more easily disposed of. you can suck the bare water off the top and either pour the rest in a drain or it will dry into a dust and you can put it in your regular trash, also theirs waste management centers that take it i believe as well. its also an overnight process not a several week process like the molasses quote states.
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post #4 of 30 Old 07-14-2012, 09:24 AM
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My jeep seems at times to be more rust than metal, so this thread is interesting. The chelation process you are referring to with molasses I wasn’t aware of, but amfamiliar with chelation in boiler water and cooling tower water treatment toprevent rust and scale in chemical plants. The downside of the molasses chelation seems to be the time it takes andthe odor, from what I’ve found on the net. Seems there are ‘green’ products available that are sewerable and shouldnot affect your ground water, but then you also said you have alternate meansof disposal. The chemical formula forrust is Fe2O3.nH2O and The overall chemical equation for the formation of rust is
Iron + water + oxygen = rust

4 Fe(s) + 6 H2O(l) + 3 O2(g) = 4 Fe(OH)3(s)

Iron(III) hydroxide, Fe(OH)3 then dehydrates to produce Fe2O3.nH2O(s)or rust.
Chelation is the formation or presence of two or more separate coordinate bonds betweena polydentate (multiple bonded) ligand and a single central atom, ligands are called chelants, chelators, chelatingagents, or sequestering agents.

Thechelate effect describes the enhanced affinity of chelating ligands for a metalion compared to the affinity of a collection of similar nonchelating(monodentate) ligands for the same metal.

Considerthe two equilibria, in aqueous solution, between the copper(II) ion, Cu2+ and ethylenediamine (en) on the one hand and methylamine, MeNH2 on the other.

Cu2+ + en = [Cu(en)]2+(1)

Cu2+ + 2 MeNH2 = [Cu(MeNH2)2]2+(2)

In (1)the bidentate ligand ethylene diamine forms achelate complex with the copper ion. Chelation results in the formation of afive–membered ring. In (2) the bidentate ligand is replaced by two monodentate methylamine ligands ofapproximately the same donor power, meaning that the enthalpy of formation of Cu—N bonds isapproximately the same in the two reactions. Under conditions of equal copperconcentrations and when the concentration of methylamine is twice the concentrationof ethylenediamine, the concentration of the complex (1) will be greater thanthe concentration of the complex (2). The effect increases with the number ofchelate rings so the concentration of the EDTAcomplex, which has six chelate rings, is much much higher than a correspondingcomplex with two monodentate nitrogen donor ligands and four monodentatecarboxylate ligands. Thus, the phenomenon of thechelate effect is a firmly established empirical fact.

The thermodynamicapproach to explaining the chelate effect considers the equilibriumconstant for the reaction: the larger the equilibrium constant, thehigher the concentration of the complex.

[Cu(en)] =β11[Cu][en]

[Cu(MeNH2)2]= β12[Cu][MeNH2]2

Electricalcharges have been omitted for simplicity of notation. The square bracketsindicate concentration, and the subscripts to the stability constants,β, indicate the stoichiometry ofthe complex. When the analyticalconcentration of methylamine is twice that of ethylenediamine andthe concentration of copper is the same in both reactions, the concentration[Cu(en)] is much higher than the concentration [Cu(MeNH2)2]because β11 >> β12.

Anequilibrium constant, K, is related to the standard Gibbs free energy, ΔG by

ΔG =−RT ln K = ΔH − TΔS

where Ris the gas constant and T is thetemperature in kelvins. ΔH isthe standard enthalpy change of the reaction and ΔS isthe standard entropychange.

Sorry about that, it is the chemical engineer in me. To simplify all that bruhaha and make a long story short, that laboriousexplanation was merely to point out how the chelating agent (molasses, phos acid, etc) displaces (bonds with the rusted material) therusting/oxidizing agent and once removed, the metal can be coated withsomething (paint, chrome, etc) to prevent the introduction of moisture, which facilitates the oxidation. Products like Evapo-rust are chelatingagents for sale that is environmentally safe and sewerable. When I sealed my gas tank with POR, Ipassivated the rust with a phosphoric acid product which was also sewerable and similar to the spray on product used in Matt's post, that I just happened to already have in the shed. This is some info/hype on evapo-rust fromtheir website (the advantage here being the lack of the odor and a much shortertime frame than with molasses):

EVAPO-RUST is an amazing awardwinning rust REMOVER which is utilized by the U.S. Army, U.S. Navy, U.S. AirForce, FBI, NATO, Government Contractors, Engine Builders, Auto Enthusiasts,Gunsmiths, Forensic Labs, OEM’s, Farmers, Antique Restorers and more.

EVAPO-RUST is non-corrosive tosteel and does not harm brass, copper, aluminum, gold, lead, titanium, steel,cast iron, chrome, solder points, vinyl, plastic, rubber, silicone, glass,cork, or wood. EVAPO-RUST has an indefinite shelf life* and can be used overand over until it absolutely stops working. On average, one gallon de-rusts upto 300 pounds of light to moderately rusted steel.

EVAPO-RUSTis easy to use. Fully immerse the rusted item in EVAPO-RUST and check progressin about 30 minutes; no scrubbing necessary. Soak times will vary from 30minutes to 24 hours depending on severity of rust, type of steel, andtemperature. EVAPO-RUST is water based, therefore the active molecules willslow down as temperature decreases and increase as temperature increases. Werecommend utilizing EVAPO-RUST at a bath temperature above 60 F.

EVAPO-RUST has a surfactant toaid in penetrating oils and dirt. However, surface contaminants do slow theprocess and can shorten the life of EVAPO-RUST . Oils, greases and cosmolineshould be removed prior to de-rusting. Cleaning the part prior to soaking inEVAPO-RUST will also help in the disposal of the spent product.

NOTE: Althought Evapo-rust rustremover is designed to be a soak, it can be utilized in certain situations as aspray, a chassis was de-rusted using Evapo-Rust as a spray to de-rust a chassis.

EVAPO-RUSTworks at a pH of 6.1 to 7 (neutral) through selective chelation. This is aprocess in which a large synthetic molecule forms a bond with metals and holdsthem in solution. Most chelating agents bind many different metals. The activeingredient in EVAPO-RUST bonds to iron exclusively. It can remove iron fromiron oxide, but is too weak to remove iron from steel because the iron is heldmuch more strongly.

Once the item has been de-rusted, you have several options: 1)Washand rinse the item off and go to the next process for painting, coating, etc.2) Wash & rinse the item off and apply a long term rust inhibitor (see nextparagraph); or 3) Wash and rinse the item and dip back into EVAPO-RUST, removeand let dry. EVAPO-RUST will provide about 10-14 days of rust inhibition,depending on the humidity. Wash and rinse when ready to paint or applylong-term CPC.

To protect the cleaned metal during storage or shipment, use Rust Bandit or Daubert Cromwell corrosion inhibitorpackaging - film, paper, emitters, or other as required by the type of metal,packaging application, condition and duration of storage. For product selectionassistance, call Daubert Cromwell at 800.535.3535, e-mail, or click the logo at the bottom of thepage to access

EVAPO-RUST is non-hazardous and ships U.S. Postal, UPS or regularfreight (class 55). The product is sewerable in neat form and, in most cases,only the chelated iron content of the solution will dictate disposalrequirements. The pH of virgin EVAPO-RUST is 6.1. The pH of the spent solutionwill vary from 6.1 to 7, which means there is no need to neutralize the alreadyneutral solution. Check with your local water treatment facility and dispose ofaccording to local, state, and federal guidelines.

From another website, this seems toexplain the molasses process. I believeI’d opt for the evapo-rust or something similar.

Everyone hasheard how molasses dissolves rust, so make a trip to the local pet food andgrain store and get your molasses.
The formula is two litres of molasses in 7 litres of water. Put this mixture ina plastic bucket or container and partly cover to help stop evaporation. Leavefor about three weeks, down by the back fence (it pongs a bit), until itferments. It should now have a skin on the top, which should be peeled off. Nowyou can immerse your rusty parts in this solution. Leave for about two weeksbefore removing them, by then all the rust should be dissolved (use rubbergloves, long tongs, or tie pieces of wire to the parts before you start, asthis mixture contains ACETIC ACID).

After removal, wash off the brown muck straight away with a stiff brush underhot running water. As soon as the parts are dry, treat them with rust converterand paint them as soon as possible, or if not painted, wire brush and oil them.This must be done immediately because surface rust will start to form as soonas the metal is dry, because it is so clean it has no protection.

Apparently the water and molasses mixture when left exposed to air, fermentsand produces, amongst other things, Acetic Acid. This reacts with the oxygen inthe rust and when the iron oxide (rust) is all reduced the process stops, sothe steel or iron is not affected, but the surface of the metal is now virtuallyin original condition and subject to immediate attack by oxygen in the air andbegins to rust, so must be protected.

The benefit of using molasses is that it dissolves that rock-hard rust thateven wire brushes can't touch and carborundum cloth can't reach and by usingarrangements of odd-shaped containers like old concrete troughs half full ofdirt and lined with heavy plastic sheet, it is possible to derust largerobjects that would not stand sand blasting.

This mixture will still derust for quite some time, (six months or even more).

Hope I didn’t put anyone to sleep……..
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post #5 of 30 Old 07-14-2012, 07:09 PM
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I wish I could submerge my 5 in EVAPO-RUST over night
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post #6 of 30 Old 07-15-2012, 03:46 AM
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molasses takes way too long. id rather just go with a wire wheel and some elbow grease. had heard about evapo rust but never checked it out. id have to ship it here and a five gallon bucket would be around 100 dollars.
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post #7 of 30 Old 07-15-2012, 05:18 AM
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Evaporust is sold at harbor freight. I've used it and it does a pretty good job.
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post #8 of 30 Old 07-16-2012, 02:21 PM
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I use all three methods. I have a plastic 55 gal barrel I use for an electrolysis tank. Large parts go in the tank overnight then hosed off and wire brushed, any residual rust is treated with Ospho (phosphoric acid).
Small parts like nuts, bolts, springs go in to EvapoRust, that stuff is great.
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post #9 of 30 Old 07-16-2012, 02:47 PM
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I don't know much about chemical rust removal, but i sure am a fan of mechanical rust removal. I recently had my entire frame blasted for $250, well worth it to me. I am now doing all the little do-dad pieces and hate wire wheeling.

Hence i am one more wire wheel injury (so basically next time i use it) away from heading to my favorite crappy chinese tool store and dropping $200 on this baby. For the infrequent use as a weekend warrior it would get, i assume this chinese made non-industrial blaster would be fine. And it sure would speed things up also. Problem is the garage gets smaller every time i buy another tool!

Looks like it would house anything the size of the skid plate and smaller basically. With the exception of the block, frame, quarters, grill, body and axles, most everything else should fit in there. That is a lot of parts!

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post #10 of 30 Old 07-16-2012, 03:26 PM
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The chemical stuff does the trick for the remaining rust that just wont come away or is in too tight a spot.

A word of warning on the HF cabinet. That thing is an ergonomic nightmare. The glove position in relation to the distance to the viewing window is all wrong. It puts you in a hunched position that sent me to the chiro for an adjustment.

You will not find a new one cheaper but if you could find a used cabinet, look for one that stands taller as to allow you to stand more vertically.
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post #11 of 30 Old 07-16-2012, 03:31 PM
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I have that blaster. Works well enough on small things. Get a tube of RTV and seal up every joint when you're assembling it. Take the light apart and seal that up.

I hate using it though because it coats everything in the garage with aluminum oxide.

I stick to mechanical rust removal as well. Knotted wire cups on an angle grinder is my favorite method. Anything too complicated to hit with that gets sent to the blaster.

If something needs to be etched, then I will use phosphoric acid.

I picked up some evaporust today to clean miscellaneous hardware because I'm tired of blasting nuts and bolts. I cold blue all my hardware after its been cleaned up.
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post #12 of 30 Old 07-16-2012, 03:53 PM
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Phosphoric acid works great. I've used prep and etch and made my own by ordering some 18 molarity and diluting it down to 2 molar phosphoric acid. It did an awesome job on the frame but handle with care

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post #13 of 30 Old 07-16-2012, 09:29 PM
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I recently purchased a 20 ton shop press from Greg Smith equipment sales for the exact same price as the one at Harbor Freight. The quality and finish of the one at Greg Smith was much better IMO. Their showroom had tons of blast cabinets of better quality and comparable prices to Harbor Freight. I buy lots of stuff from HF, but now I'm gonna check both places.
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post #14 of 30 Old 07-17-2012, 11:26 AM
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This is the cabinet I am using right now. It is great. Much less stress on my back. For the record, I stripped my jeep and used the HF blasting cabinet for hours. So much so that I blew the copper tube in the 80gal compressor due to over heating.

Much more expensive but if you can afford it, that is the one to get.
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post #15 of 30 Old 11-25-2013, 03:03 AM
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Using acid over the metal may destroy the protective letter from the surrounding surface. Removal of rust from metal can be a tough job. We need to adapt to new methods for prevention and removal of rust from metals.
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