Dipping Watch Parts in Oxalic Acid - Does Anyone Have Any Experience?

[Gramham]

Hello Everyone,

I will be picking up some Oxalic Acid tomorrow so I can perform some experiments on rusted steel in support of my upcoming paper Why (and How) We Clean Things.

Does anyone have any experience with Oxalic Acid?  I am open to tutelage in terms of general materials handling (the stuff is pretty strong) and especially interested in how it might be used to clean steel watch parts.  

My intention is to use Oxalic Acid to remove rust from the end-stage Winding Work parts:

- Crown Wheel(s)
- Barrel Ratchet Wheel(s)
- Ratchet Wheel Pawl ("click")



Am I crazy to do this?  How crazy?  Why?



g.
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[HectorLooi]

I picked up a 5Kg tub of oxalic acid earlier this year after watching some YT videos on how wonderful it is. But after some experimenting, I don't find it very effective.

I tried removing rust stains from cloth, removing rust from screws, yoke springs, lime scale around the taps, etc. And I wasn't impressed.

Previously, I used hydrocloric acid, phosphoric acid and citric acid for rust removal. All of these work better than oxalic acid but are more prone to creating pitting of the surface. I also tried a 50/50 mix of citric/oxalic acid. This seems to work best.

Let us know your experience when your oxalic acid arrives

[Gramham]

2 hours ago, HectorLooi said:

I picked up a 5Kg tub of oxalic acid earlier this year after watching some YT videos on how wonderful it is. But after some experimenting, I don't find it very effective.

I tried removing rust stains from cloth, removing rust from screws, yoke springs, lime scale around the taps, etc. And I wasn't impressed.

Previously, I used hydrocloric acid, phosphoric acid and citric acid for rust removal. All of these work better than oxalic acid but are more prone to creating pitting of the surface. I also tried a 50/50 mix of citric/oxalic acid. This seems to work best.

Let us know your experience when your oxalic acid arrives

Hello @HectorLooi,

Do you remember what concentration and duration you worked with?

I too am interested in the other options, and especially in phosphoric acid because of the conversion as opposed to loss factor - but I'm starting with a oxalic because it's the first one I could source easily.  Your list and my list of acids is pretty much the same, though I would also add acetic acid to the list because it's so safe to handle in typical solution(s) like white vinegar.

g.

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[nickelsilver]

I use a shop-mixed clock cleaner that was developed at the Finnish watchmaking school that uses some oxalic acid in it. I've mentioned it before but the recipe is:

1 liter 99% isopopyl alcohol

3 liters distilled water

50g oxalic acid

60g oleic acid

approximately 80g of 24% ammonia

To mix, heat the alcohol until very warm in a big pot, add oxalic and oleic acid and mix well, add the water, the solution goes all cloudy. Add the ammonia, slowly, stirring, until the solution turns clear, that's the right amount of ammonia. It's a rather abrupt change. At this point the ammonia has combined with the oleic acid to form a soap.

 

I haven't really noticed that this solution removes rust, but I imagine the oxalic is in there as a boost and maybe helps clean oxidation a bit. I've tried it at at stronger concentration, like 30g in 1 liter of water, and it does de-rust, but not like other acids. But, it does seem gentler to the underlying steel like Hector observed. One issue I have with using acids on steel for rust removal is hydrogen embrittlement. I don't know all the facts and science behind it, just that it is an issue and I don't want issues down the road, so I tend to do only mechanical rust removal.

[Neverenoughwatches]

7 hours ago, Gramham said:

Hello Everyone,

I will be picking up some Oxalic Acid tomorrow so I can perform some experiments on rusted steel in support of my upcoming paper Why (and How) We Clean Things.

Does anyone have any experience with Oxalic Acid?  I am open to tutelage in terms of general materials handling (the stuff is pretty strong) and especially interested in how it might be used to clean steel watch parts.  

My intention is to use Oxalic Acid to remove rust from the end-stage Winding Work parts:

- Crown Wheel(s)
- Barrel Ratchet Wheel(s)
- Ratchet Wheel Pawl ("click")



Am I crazy to do this?  How crazy?  Why?



g.
----

I did a little research and a post a while ago on rust removal and did come across oxalic acid. Personally i didn't think it worth a mention as there are much more readily available alternatives that do a fantasic job. The acetic acid in vinegar works extremely well. The water content did concern me but as long as the parts are thoughly and quickly dried its not an issue.

[Shane]

https://www.google.com/m?q=washing+soda+rust+removal&client=ms-opera-mobile&channel=new&espv=1

I've used this process about 20-25 years ago for cleaning a very rusty antique engine block before rebuilding it.  It worked great.  I didn't notice a significant loss of the base material or pitting but since it was all done before any machine work my standards were low.  I was concerned about hydrogen embrittlment but that's mostly a concern with harder alloys having a tighter grain structure.  From what I remember, the atomic hydrogen can get into the steel recombines into diatomic hydrogen and can't get back out and acts like an anit aggregate.  I also used this method more recently for prepping a set of wheels for my four wheel drive truck.  Still concerned and since the stakes are higher, I limited the duration and cleaned more of them manually.

Good luck and keep us all informed.

Shane 

[HectorLooi]

19 hours ago, Gramham said:

Do you remember what concentration and duration you worked with?

No. I just put half a tsp of each into jam jar filled it with enough water to dissolve it. It was probably quite concentrated. 

I sometimes mix dry citric acid, oxalic acid and scouring powder and add a little water to make a paste for scrubbing out stubborn dirt around the house, like soap scum in the shower, calcium deposits around the base of the taps, etc.