Molasses Rust Removal

[Phil Waterman]

Hi Guys

One comment/question that I would add on molasses, washing soda, electrolysis, cleaning/degreasing of parts, temperature of the fluid.

I've tried most of these different methods for degreasing and rust removal, what I have noted is the temperature plays a big part in how quick and well the process works.

For example washing soda at 180F/82C will degrease and remove paint from small parts just soak the parts for 1/2 hour and then scrub the with a medium stiff brush and the grease and even the OD paint comes off. Yet soak the same parts in same solution overnight at room temperature and nothing happens.

Washing Soda when used for electrolysis doesn't seem to work for rust removal when the solution is much below room temperature. Discovered this, one winter, when I had my plastic tube in the corner of the shop away from the furnace result the tank never got much over 40F/4C rust removal was very slow yet when it was in the direct hot air blast of the furnace progress was much better.

Has anybody else noticed temperature as being a significant factor?

Cheers Phil

[jack neville]

I'm using washing soda and electrolysis with the power supply being a cheap 240/12 volt converter brought off ebay. Wheelie bin is outside. Working a treat but then it is summer in Australia. Strips rust and paint.

[Lynn Eades]

Jack, what amperage is your power supply? there are currently some 240/12v 4 amp ones for sale here for $20 is it good thing?

[jack neville]

Originally Posted by Lynn Eades

Jack, what amperage is your power supply? there are currently some 240/12v 4 amp ones for sale here for $20 is it good thing?

I think it is about 4 amps. Post a photo. Sounds the same.

[Matt Stephenson]

Hi all,

As an alternative, a citric acid bath also does the trick. I buy it in a 1kg pack from a swimming pool shop and mix it with tap water. Usually 2 scoops to about 20 litres of water. Removes rust and paint back to bright bare metal after about 2 to 3 days of immersion.

Im also trialling the use of Apple Cider Vinegar. So far I've used it on some small parts and the results have been surprising, with the items cleaned and rust free after a 6 to 10 hour immersion. The only problem is the availability and cost of the vinegar, so probably better for small parts only.

Regards,

[Niels V]

I must just point out, with electrolysis be careful with hydrogen formation, make sure the room is well ventilated.
And never use it for high strength steel or load bearing stuff you risk introducing hydrogen in the material, this leads to hydrogen embrittlement => almost spontaneous failure/cracks.
To reverse this parts have to baked at 200 C for quite some time to drive out the hydrogen.
In molasses it is possibly phosphoric / citric acid that is the active ingredient.

[cletrac (RIP)]

The modern way to do it!

I was amazed at how this works in the video.

[Wayne Hingley]

Originally Posted by Phil Waterman

I've tried most of these different methods for degreasing and rust removal, what I have noted is the temperature plays a big part in how quick and well the process works.

Very true Phil. Temperature has a great impact on pH. As the temperature increases, the pH will decrease (ie; the solution becomes a stronger acid). The molecules in the water will also become more active as temperature increases.

It should also be possible to speed up the process by agitating the solution, so that more fresh exchanges occur between the solution and the parts.

[Bob Carriere]

I have used a 45 gallon drum with a lye solution..... afull perimeter stainless steel plate with a 10 amp battery charger and two 12 volts truck batteries....... batteries went flat in a 2 hours and charger overheated......... it was really bubbling and cleaned a suspended cast CMP axles inside and out in 2 hours...... heavy scumof oil and paint on the surface.

Pressure washed and sun dried it looked like new.

Not sure how many amps were going in or how we could measure based on plate size .........

What is it in molasses that does the derusting...... the potassium content??? and if so would not a weak potassium acid bath be cheaper, faster, less sticky and stinky without being lethal to the environment?????

Bob C

[Wayne Hingley]

Originally Posted by Bob Carriere

What is it in molasses that does the derusting...... the potassium content??? and if so would not a weak potassium acid bath be cheaper, faster, less sticky and stinky without being lethal to the environment?????

Bob, I believe molasses has a pH of around 5-6, which means it is acidic. I suspect it is the organic acids that are responsible for the de-rusting process. Since it is a relatively weak acid, it is not too destructive on the parts (as everyone has noted). Thats also why it takes a bit of time to produce results. If you go to a stronger solution, it may be faster but also more damaging to your sensitive parts.

[Bob Carriere]

....the organic acid is?????

In sheet metal plants they wash the metal with a powder disolved in water.....very weak solution and I "think" it was potassium solution....... and they worked bare hands........ they dipped the plates only a few minutes than wash/rinsed with hot water to speed drying.....

[Jacques Reed]

What is it in molasses that does the derusting...... the potassium content??? and if so would not a weak potassium acid bath be cheaper, faster, less sticky and stinky without being lethal to the environment?????


Hi Bob,

Here is a link to just one of many explanations on how molasses and water works. Not necessarily to be taken as Gospel though. "Chelating" needs to be researched further. It may be safer than other caustic or acetic chemicals used for rust removal but that could just be the authors opinion.
His comments about pot metal, zinc castings, are correct though. Ditto for galvanized parts. It will remove galvanizing.

Environmentally it may be better too. Shipmates on chemical tankers told me that when they carried molasses in bulk they were even allowed to wash the tanks after discharging it and pump the slops into the sea. Apparently the fish loved it. With the strict regime of managing tank washing and recording it I doubt the authorities would allow it if it was extremely hazardous to the environment. It is, after all, a by product of sugar manufacture and we all know how good sugar is for us!


http://www.homercidal.com/molasses/

Cheers

[lynx42]

As you may remember from my Lynx restoration thread, I used molasses a heck of a lot to clean almost every small part. I use a 10 to 1 mix and find that it does work faster in the warmer months.

Lynda Griffith082013 025.jpg

Some of the many small bits that make up a Lynx after they have been in the solution and wire brushed after being pressure washed.

Lynda Griffith082013 034.jpg

I am lead to believe that there is no acid working to remove rust but an ALGAE which feeds on the oxygen in the rust. Rust being iron oxide (Fe2 O3). All you are left with is the iron as a black fine mix on the bottom of the solution. That is why it is safe to get on your skin and to dispose of on the grass without hurting the environment.

Regards Rick

[Tony Wheeler]

Originally Posted by Jacques Reed

"Chelating" needs to be researched further.

Hi Jacques,

You may have to wade through quite a few scholarly articles to find anything relevant to molasses. Try search terms like "biological rust removal" or "siderophores in rust removal". Also think about possible industry use, eg. environmental applications such as cleanup of contaminated sites (heavy metals) or perhaps sewage treatment. Quick search turned up a few mentions here:

http://www.envismadrasuniv.org/nl200...sidephore.html

"Sidephores in rust removal: Bacteria, fungi and plants are using biological chelating compounds in order to efficiently bind iron ions. So rust layers can be abated in a natural and gentle way. Biologists, mineralogists and biotechnology engineers have been investigating the process of biological rust removal for many years."

Who knew!!

"Iron is an important element for all living cells. It is difficult to take up iron into cells due to its poor solubility. For the iron supply of living cells, some microorganisms including bacteria, fungi, actinomycetes and algae produce an iron chelator, siderophore, outside the cells and the siderophore is chelated with ferric iron. The role of these compounds is to scavenge iron from the environment and to make the mineral, which is almost always essential, available to the microbial cell."

"Research in this field begun about six decades ago, and interest in it accrued with the realization that most aerobic and facultative anaerobic microorganism synthesize at least one siderophore. In addition, they have applications in clinical, agricultural and environmental fields. At present nearly 500 siderophores are reported from selected microorganisms."

"Currently the applications of siderophores in clinical, agricultural and environmental sector are reported in some extent. But the siderophore research is not at all initiated in most of the microbiology research laboratories. So, there is a need to discover siderophores from normal and also extremophiles in the ecosystems like deep sea, desert and forest to exploit their applications for welfare of all living beings as well as for environment, particularly cleanup of heavily rusted CMP vehicle parts."

OK, so I added that last bit. Point being that if we can identify the most suitable bugs we can selectively grow them in our molasses bath. That means providing the ideal growth medium (dilution rate, temperature, pH, additional nutrients, oxygenation) and introducing the chosen species in large numbers, preferably in active form, so it can rapidly multiply. In other words, just like home brewing or wine making, where you select the desired yeast strain and pitch it in quantity into your wort (beer) or must (wine). In this way the lag time is reduced dramatically, from several weeks to several hours, and the desired species predominates. Of course, in this case we're trying to produce siderophores, and since the strongest known siderophore is Enterobactin, which is produced by E.coli, I shall leave it to your imagination how best to introduce active E.coli in quantity into your molasses bath!


On the question of alternatives it must first be noted: "Chemically siderophores are iron binding proteins with molecular weight ranging from 400 - 1500 Da." Key word: PROTEINS.

Alternative chelating agents are ORGANIC ACIDS: citric acid, acetic acid, EDTA (Ethylene-Diamine-Tetra-Acetic acid). These bind a range of metal ions, and in addition to household use for removal of scale (calcium, lime, rust) they find extensive use throughout industry in a wide range of applications. These can be researched quite readily, eg:

http://www.glossary.oilfield.slb.com...ing_agent.aspx

"Chelating agents associate with iron [Fe+3 or Fe+2] to form soluble complexes. Citric acid, acetic acid and EDTA are effective chelating agents and can be used at temperatures up to 400oF [204oC]."

This suggests they may find use in hot tanks as an alternative to caustic soda, perhaps for non-ferrous metals like the pot metal you mention Jacques. Also if it works rapidly on rust it may be useful for small parts when you need them in a hurry. Just boil them up in a saucepan on the stove! Also worth investigating are inhibitors added to prevent flash rusting.

I notice Matt has trialled citric acid and acetic acid (in vinegar) with good results it would seem. I bought some EDTA on ebay which I'll be interested to trial as well: http://www.ebay.com.au/itm/EDTA-4Na-...UAAOSwZd1VW2YO

Something else I'd like to investigate for small parts is Immersible Ultrasonic Transducers.

Cheers,
Tony

[Tony Wheeler]

Originally Posted by Bob Carriere

What is it in molasses that does the derusting...... the potassium content??? and if so would not a weak potassium acid bath be cheaper, faster, less sticky and stinky without being lethal to the environment?????

Apologies Bob, I've only just stumbled on your question. I've never given much thought to the molasses method but the active agents will be siderophores: "Siderophores (Greek: "iron carrier") are small, high-affinity iron chelating compounds secreted by microorganisms such as bacteria, fungi and grasses. Siderophores are amongst the strongest soluble Fe3+ binding agents known."

One candidate may be Enterobactin: "Enterobactin is a high affinity siderophore that acquires iron for microbial systems. It is primarily found in Gram-negative bacteria, such as Eschericia coli and Salmonella typhimurium."

E. coli may explain the stink you mention Bob. However it's really anybody's guess what you're growing in there. Molasses is rich in nutrients so you're basically creating a giant petri dish. It will be colonized by all manner of airborne microorganisms, particularly in Spring and the warmer months when they're most prevalent. Plus of course whatever animal droppings happen to get in.

On the question of alternatives the ideal compound would be EDTA. It's a widely used synthetic chelating agent which I know about only in theory, but which I'm quite certain would be far superior to molasses method. The only question would be cost and availability in bulk, as it appears to be produced exclusively in China with minimum order quote in metric tons! However my search for "industrial grade EDTA" returned lots of these which you may be able to source locally:

EDTA.jpg


Meanwhile I found some on ebay which looks ideal for trialling:

http://www.ebay.com.au/itm/EDTA-4Na-...UAAOSwZd1VW2YO

[Bob Carriere]

From China or Greece.......

...delivery "soon" ......hum!!!!

And interesting that it can be added to lye water mixture..... probably for a soap solution......

sounds like the kind of stuff that the Homeland security would monitor to see who buys it.......

so basicaly a bacteria that can feeds on iron oxide !!!!

I think I will stick to my lye/water solution with DC current and/or sandblasting..... as crude as it may be at least I am familiar with it.... and its risk.

Cheers