No Tank Electrolysis or Anodising?

[Grant McCullough]

Originally Posted by Lionelgee

Hello All,

I decided to watch a YouTube clip Old Soviet motorcycle full Restoration, accessed 17th January 2021 from https://www.youtube.com/watch?v=y8HEZ-x4-_w .

The clip showed an electrical treatment that did not involve the usual tanks and immersion I associate with electrolysis rust treatment. Can someone confirm what the type of treatment actually is for me?

The treatment appears as follows - with timestamp in brackets [ ] ...

[6:00] taking alloy sheet out of AA battery cutting the alloy into small squares. Partially filling a glass jar with Orthophosphoric acid (Phosphoric) [6:24] and putting the alloy squares into the acid. Getting another AA and placing some cloth over the negative end of the AA battery.

Getting a 12 volt car battery and hooking an earth lead up to a steel motor cycle rim [6:52). The second lead is hooked to the positive terminal and the other end of the lead is hooked onto the positive end of the cloth covered AA battery.

The cloth end of the AA battery is dipped into the glass jar [6:57]. The wet cloth end of the AA battery is then rubbed on the steel motor cycle rim which completes the circuit [7:06}.

After treatment the rim is sanded down [7:25]

Is there a specific name for this treatment and what is it used for? How good or functional is this process?

Kind regards
Lionel

It is called electrolytic or electroplating, it shows him making his plating solution by dissolving the zinc strip from a battery directly into phosphoric acid. By using the brushing method he is applying a zinc plate (Rust protection)to the steel rim wiith the benefit of filling any small pitted areas too. I believe the phosphoric acid also chemically changes the red rust into black iron oxide, which also protects from corrosion. The sanding is to remove any high spots in the plating process and to give a good surface for paint adhesion. Here are a few videos describing the processes .

https://www.youtube.com/watch?=G-PtnwtOR24

https://www.youtube.com/watch?v=_Urr8BzgUog

https://www.youtube.com/watch?v=iS8Cke3CLC4
On some phosphoric acid based rust remover/converter products I have seen, they have a warning ...May cause hydrogen embrittlement.

The old dnepr/ural looks much nicer now.

[Lionelgee]

Originally Posted by Grant McCullough

It is called electrolytic or electroplating, it shows him making his plating solution by dissolving the zinc strip from a battery directly into phosphoric acid. By using the brushing method he is applying a zinc plate (Rust protection)to the steel rim wiith the benefit of filling any small pitted areas too. I believe the phosphoric acid also chemically changes the red rust into black iron oxide, which also protects from corrosion. The sanding is to remove any high spots in the plating process and to give a good surface for paint adhesion. Here are a few videos describing the processes .

https://www.youtube.com/watch?=G-PtnwtOR24

https://www.youtube.com/watch?v=_Urr8BzgUog

https://www.youtube.com/watch?v=iS8Cke3CLC4
On some phosphoric acid based rust remover/converter products I have seen, they have a warning ...May cause hydrogen embrittlement.

The old dnepr/ural looks much nicer now.

Hello Grant,

Thank you for identifying the process used to restore the Soviet motor bike's wheel rims. It is named in the second video as "Brush Plating".

I was surprised when the voice over came on the first youTube link and it was a Geoffrey Croker video. I watch Geoffrey's Land Rover Series 3 restoration videos as I have projects of the same ilk.

The second video shows a commercially available version of the Soviet home-made process. Thank you also for posting the clip about the phosphoric treatment. Maybe I should of persevered with my Senior Chemistry for longer than a week, before swapping out to another subject!

It is good to know what the process is called "Brush Plating"; or as Youtube has informed me, the process is also known as "Wand Plating". I am off to watch some more YouTube clips :0)

Kind regards
Lionel

[David Herbert]

Originally Posted by Grant McCullough

. I believe the phosphoric acid also chemically changes the red rust into black iron oxide, which also protects from corrosion..

Actually the phosphoric acid either removes the rust by dissolving it or if it can't take up any more into solution it changes the remaining rust (Ferrous oxide) which is not chemically stable into ferrous phosphate (which is black), which is chemically stable. It is however still porous and so needs a protective layer of paint.

Most self etching primers like Bondaprimer (sold in the UK) contain phosphoric acid as their active ingredient. Almost any acid will dissolve rust but most will leave an unstable surface that readily combines with oxygen causing almost instant rusting. The key is to leave a non reactive, stable surface.

David