Flash rust removal.

[SteveD]

I derusted a 78 frame during lockdown last year. It was crusty. It now has a fair bit of flash rust on it.

What are your preferred BUDGET techniques for removing it? Cheers.

Boiled linseed has been recommended.

I plan on painting, not powdercoating it.

[Rob Frankham]

The best way is to remove it electrolytically... however you need to submerge the workpiece in solution to do it.

There are numerous pages and videos on how to go about it but, in essence, the workpiece (frame) is suspended in an alkaline solution... washing soda is a regular choice... and surrounding it with sacrificial anodes (basically pieces of wast metal which will be eroded by the precess). fairly close but not touching. DC Electric connections are made to both the workpiece and the sacrificial anodes. It is essential to make sure that the negative supply is connected to the workpiece and positive supply to the anodes (otherwise the workpiece will be eroded!!!). Voltage and current isn't critical. A common solution is to simply to link up a vehicle battery. Currents may be quite high in a workpiece as large as a frame and a fuse in the supply is a VERY good idea as any contact between an anode and the workpiece will produce a direct short.

The benefits of the process are:

It removes the rust but doesn't remove any of the sound metal (unlike any abrasive process).

It also tends to remove paint and any other surface contamination.

The effect is more pronounced where the workpiece and anode are closest but it will remove rust from hidden and inaccessible areas even if it takes a bit longer.

It doesn't require an enormous amount of 'elbow grease.

Some (a small proportion) of the rust is deposited back onto the workpiece as elemental iron which has some protective qualities (Note, some proponents claim that the rust is turned back into steel. This isn't the case. That steel is gone forever).

Drawbacks:

You need a suitable sized tank for the workpiece. Plastic storage boxes are quite cheap but getting one large enough for a complete frame will prove difficult. I have had succesful results with a large box by doing thejob in two sittings. There is a drawback with this though (see next point).

Once the process is completed, you need to protect the surface immediately. The surface is completely unprotected steel and will start to rust straight away. If you can't paint straight away, you need to cover the surface with a rust protection like grease otherwise you'll be back where you started.

This process is cheap and simple but, like most things, it requires a bit of planning and care.

Rob

[SteveD]

Thanks Rob. I'm sure there are tubs of various types that would be the right size. I have seen this technique used before and successfully too. They were small bits and pieces...tools.

So far all I've tried is rubbing it off with vinegar. A bit tedious but cheap...just time and elbow grease. I'll stick with that unless someone has a simple cheap and reasonably easy method.

I have some Zinc Guard Rust Reformer in a pressure pack. It'll get a good spraying pdq this time once I've cleaned it up.

First thing will be to add some weld to where the centre stand hits it.

[Kurt in S.A.]

I haven't done this on such a large piece, but I needed to get some rust off of the nuts and washers on a mechanical clock I was working on. I bought a bottle of Rustoelum rust remover...it's a gel. I poured a little in a bowl and put the items in there for a couple of hours. I was pretty impressed with how it clean them up.

Kurt in S.A.

[SteveD]

I haven't done this on such a large piece, but I needed to get some rust off of the nuts and washers on a mechanical clock I was working on. I bought a bottle of Rustoelum rust remover...it's a gel. I poured a little in a bowl and put the items in there for a couple of hours. I was pretty impressed with how it clean them up.

Kurt in S.A.

Thanks Kurt. I'm wondering if a vinegar gel might work. The vinegar sure does and making it a gel might help it soak a bit longer?