Rust removal with molasses.

**rijidij** · 12th October 2010, 01:30 PM

A mate recently told me about using a molasses dip to remove rust from old parts.
Yeah, yeah, I know…….some of you old timers on here will say, “ I’ve been using molasses for the last hundred years to remove rust from some of my old Landy parts.”

Anyway, just for interest, I thought I’d give it a try.

First, get some feed grade black molasses from a farm supplies store, about $9 for 5kgs, and mix it with water in a suitable container. I read to mix it anywhere from 10:1 to 20:1. Mine ended up about 15:1.

I had some springs for my 2A that needed cleaning up, and a couple of rusty old hand winches.

I was told to soak the things for a couple of weeks. I took the springs out after 3 weeks and hosed them off. There was pretty much no sign of rust on the outer surfaces, except for where the rust was thicker or slightly flaky, so I pulled them apart.

At this stage I hadn’t done any wire brushing, I just wanted to see how effective the molasses is.
After another week of soaking I hosed the leaves off again. It appears that where the rust is mild, it completely disappears right back to clean bare metal, but where the rust is heavier, it seems to sort of work like a rust converter, but it’s still there.

Also, it is not effective where there is grease on the surface, so de-greasing at the start might be helpful.

Reading about the process on the net, it was stated now and then that your items will start to rust again as soon as you take them out of the dip. It does appear this way, but to me it looks more like a sort of dusty residue that brushes off easily.

I took the winches out after 3 weeks and there was a big difference. Just for interest, I gave one of the winches a light wire brush (hardly touched it really) and put it back in the dip.

After another couple of weeks I took the winch out and gave it a hose off. The following pictures are after hosing off, but no wire brushing, just straight out of the dip.

The before and after shot tells the story.

Apparently it’s a method popular with old car restoration because it's not too harsh on small or thin items. Here’s a couple of shots from the net.

Conclusion………..It’s obviously a slow process, but it works and works well. Best on light rust and grease free surfaces.
For items like the spring leaves, I would probably just attack them with a wire wheel on an angle grinder next time, but for more intricate items like the winches it’s an excellent method which gets into every nook and cranny that might otherwise be quite difficult to get to. It would be great for rusty tools too.

There are commercial products available which I’m guessing work quicker, but probably cost more too.

There’s another rust removal method I’d like to try one day too….. electrolytic rust removal……… explained Here .

So, what other methods of rust removal have you used successfully ??

Cheers, Murray

**p38arover** · 12th October 2010, 01:33 PM

Yep. I've been doing it for over 20 years.

See Getting Rid of Rust

**stealth** · 12th October 2010, 01:59 PM

I made an acid bath using a 1000 litre white plastic drum. You know the square type that come on a caged pallet. Just cut the top off. I bought 20 litres of Phospheric Acid which you dilute 10.1. It works very well on light and heavy rust and quite quickly. Light rust will strip overnight and heavy scale will take a couple of days. It helps to take it out and chip the scale off after the lighter rust has been eliminated. It can be quite effective on loosening old paint as well. Then just hose off well with water. As soon as it is dry it will start to rust again so I treated everything with fish oil which is great for creeping into seams and crevices and seals the metal. Once the fish oil has dried it can be primed and painted as normal. I restored a LJ Torana coupe for my son a few years ago and rebuilt the body shell which was riddled with rust. Using a reasonably sound donor 4 door body I cut all the rust repair pieces out and treated any rusted bits in the acid first. The end result was a solid body and no rust. The entire body was fish oiled inside and underneath and in all panel joins and seams. I didn't use fish oil on the external panel surfaces where it was not needed. It was then coated in red oxide, primed and painted using acrylic laquer. There was no problems with any paint reaction and the finish in the end was superb. I have other things that I treated in the acid and fishoiled which have not been painted over and they have been sitting around for about 4-5 years and the rust has not re-appeared. Sealing with the fish oil is the key I think. Where possible I prefer sandblasting to remove rust and priming with two pack primer. The surface preparation is so much better and the primer sticks forever. Might be expensive but you get what you pay for. Sand blasting has its limitations on lighter sheetmetal though and doesn't get into tight surfaces. Warning on the acid though. It is totally unsuitable for cast metal and high tensile steel (Springs, brake drums, casings etc). It starts to dissolve the surface very quickly. It will completely dissolve cast aluminium. It will dissolve ordinary mild steel eventually as well but that takes a long time. Very effective

**350RRC** · 18th October 2010, 09:59 AM

Posted this info before........ Hydro tomato farms use phosphoric acid to control pH levels because it is much safer for employees to handle compared with hydrochloric, for example.

20 litre drum (about 80% conc) cost me $65 from a mate with a hydro farm.

One trick using this diluted (about 10% conc) is to let the part dry without washing the acid off. Can be painted over when dry and resists further rust for a very long time on parts such as washers on alloy wheel nuts.

cheers, DL

**85 county** · 18th October 2010, 11:02 AM

Phosphoric acid you can recycle. Cool it down and a crystal will form. Filter add more water and you are all go again.

Crystal’s ferrous sulfate can go on the garden in very small quantities

**jazzaD1** · 18th October 2010, 11:27 AM

I use the electrolysis method, using some scrap steel as an anode, and a Sodium Carbonate solution as the electrolyte, it works great, and fast, it removes paint in sheets, degreases parts and removes all traces of rust

I'll try and get some pics up here soon

**slug_burner** · 18th October 2010, 06:22 PM

Originally Posted by jazzaD1

I use the electrolysis method, using some scrap steel as an anode, and a Sodium Carbonate solution as the electrolyte, it works great, and fast, it removes paint in sheets, degreases parts and removes all traces of rust

I'll try and get some pics up here soon

I too can vouch for the electrolysis method. I used electric soda crystals as used in bath salts. It worked fairly quickly, I did not have the patience to do the molasses method.

**Mick_Marsh** · 18th October 2010, 07:04 PM

Originally Posted by rijidij

A mate recently told me about using a molasses dip to remove rust from old parts.
Cheers, Murray

Would this process be able to be done in at old metal (enamelled) bathtub? Would it eventually corrode the bathtub?

**rijidij** · 18th October 2010, 10:56 PM

Originally Posted by Mick_Marsh

Would this process be able to be done in at old metal (enamelled) bathtub? Would it eventually corrode the bathtub?

I don't think there would be any problem, even if there was some enamel chips as it's a comparatively gentle process. It seems to remove the rust, but not 'eat' the metal away.
Molasses comes from sugar cane and it's fed to animals, so it's certainly not considered a dangerous chemical.
I'm not sure what the rust eating component of molasses is.

Cheers, Murray

**Randylandy** · 18th October 2010, 11:51 PM

I'm guessing its the sugar that is corrosive. used to have some coke concentrate that they use in the drink machines. Over xmas period the rats got into it and when we came back to work should have seen the mess that stuff ate into anything and everything. Made you think twice about drinking coke.

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