Use of Alum to dissolve screws

doc_fields

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Has anyone used alum to dissolve steel screws in a movement? I know this is the watch repair forum, but I'm working on a Gustav Becker 400 day that has two screws broke flush with the plate, and in a blind hole. I'm just wanting to know if the solution will damage brass, does it have to be heated, etc. .....................doc

(and yes, I tried filing slots in the stubs, and they will not turn out because of some damage)
 

doug sinclair

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Alum will not harm the brass, but you will need to make certain that there are no other steel parts that will be harmed by the alum. Considering the size of screws that I suspect are involved, expect alum to take a while to do the job. Can anyone suggest an alternate substance to do a job on clock screws? I have used goldsmith's pickling solution on watch screws in the past. But that was on watches with nickel plates. What might this solution do to brass?
 

Gary Leck

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It will work just fine. As Doug said, make sure there is no other steel parts in the solution because alum will dissolve any steel. I used it on a 400 day clock and had no problems at all. I son't remember the ratio of alum to water but, I did heat the water and tried to keep it warm. It may take a couple of days to get all of the screw and scratching the black out of the hole every so often will help also. Good luck.
 

fuzzuki

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Common battery acid will do the same trick. And it's cheaper.

Just find any dead car battery and you're off to the races.
 

Tom Huber

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The Alum will work fine as stated above. I don't know what Fuzzuki pays for alum, but I bought mine in the spice rack at the local grocery store for 98 cents. That is certainly cheaper than any battery acid and much safer to handle.

Tom
 

ben_hutcherson

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Speaking as a chemist, I personally would not use sulfuric acid(battery acid) anywhere near brass. Sulfuric acid will react with both copper and zinc.
 

1000km

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I used this technique a few days ago to remove a sheared-off crown screw from an ETA movement.

A glass container is ideal - a small glass perhaps. Dissolve as much Alum as you can in the water. The key is to keep the solution gently warmed. If you don't, the reaction pretty much stops and the alum crystallises. I used the warming function on a rice cooker - a cup warmer would also work well.

Only ferrous metals are dissolved. A small screw will dissolve competely overnight.
 

Harold Visser

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I second the technique 1000Km uses, alum works best when the solution is kept good and warm. Why risk using bleach , battery acid etc. when alum is safe, cheap, proven and effective.....
 

fuzzuki

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I'm sorry, battery acid if free.
You can find it in any parking lot in Toronto.

I have used it for 15 years with great sucess.

You can burn out a screw in less than half an hour.
How can you go wrong?
 

Samantha

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I've always used alum from the spice rack, and like Harold V. said, it's cheaper and safer. I don't want to be digging around in a parking lot or popping hoods to get battery acid - besides, it burns the skin if it touches it, and alum won't. I've never tried bleach though.
Samantha
 

Kevin W.

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I never understood why its so dificult to obtain it here in Canada.A friend of mine in the U.S sent me some.
 

doc_fields

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Yesterday I took my unused Gevalia coffee pot, put water in it, and turned it on. After the water was heated and gone into the pot, I then added the alum, which dissolved immediately, stirred it for good measure, and added the brass plate with the steel screws in it.

I expected to see a reaction begin, like dropping AlkaSeltzer into water, but nothing discernible. One hour later, still no reaction, or so I thought. Three hours later the shiny part of the screws were gone, and it looked like a black hole there. I kept punching the "On" button to keep the warming function on every so often. Looking closely at the plate in the solution, I could see little teeny tiny bubbles coming up from the holes where the screws were. That was the reaction I was looking for, but didn't see because of its size.

I removed the plate yesterday late in the day, and picked a little debris from the holes with a toothpick, and put it back in. Hoping today it'll all be gone.........................doc

Thanks for all the comments. Alum DOES work! I much prefer a slow reaction than a quicker one and takes it's time. I'm just a little leery of acids, and not sure about bleach.
 

jkamboj

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Kevin

Let me try my source and let you know the progress tomorrow about availability of alum in Canada.

In the meanwhile, can some one suggest me alum percentage in alum solution to dissolve ss stem broken in the crown. My second question is does it dossolve the nickle plating of the crown?
I have to resicue a crown with broken stem inside.
Jaswant Kamboj
 
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jkamboj

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Doc_fields

Would you please give me an idea about the concentration of alum in the alum solution you used to dissolve steel. Just give me approximate concentration as I have to try dissolve a broken stem in a crown.
Or any one else can answer my question before I try hit and trial method please.

Jaswant Kamboj
 

Cary Hurt

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I use about one tablespoon per cup (240ml). Heat the water first to help in dissolving the alum.
 

fuzzuki

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You don't gotta pop hoods. People leave old batteries there.
That's why it's free.



I've always used alum from the spice rack, and like Harold V. said, it's cheaper and safer. I don't want to be digging around in a parking lot or popping hoods to get battery acid - besides, it burns the skin if it touches it, and alum won't. I've never tried bleach though.
Samantha
 

Kevin W.

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fuzzuki i can,t believe you would want to use something so corrosive to work on a watch, when there are much safer choices available,
 

fuzzuki

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I have used it for years, no ill effects.
If you haven't tried it why are so many of you knocking it?

I have never used Alum. Do you see me knocking it?

This is absolutly free. No dollars and no cents.

It's recycling even.

Maybe I'll try alum.
 

Kevin W.

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i guess the only problem i see is that its a acid.
Did they teach you to use this in watch repair school?
You mentioned that the schooling taught you more than a person could have learned from a past generation handed down.So they told you acid is a good thing?
Very corrosive acid is, that might be why i am knocking this.
 

ben_hutcherson

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Actually, alum is an acid also. At least, when dissolved in water, it gives an acid solution.

The key difference here, though, is that sulfuric acid(battery acid) is a strong acid.

If you look at an activity series, you'll see that iron is listed higher than copper. What this means is that iron more easily displaces the H+ from acids, or in other words it's more easily oxidized than copper.

Alum is just acid enough to react with iron, but not enough to react with copper. Thus, it's safe to use in just such an application.

Concentrated sulfuric acid will react with copper, and thus will destroy brass.

Alum is the safer alternative, not only for your own safety but also for the intended use.
 

Tom Huber

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Alum is a spice commonly used for canning pickles. It can be found in the spice rack of any grocery store.

Tom
 

Kevin W.

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Except in Canada where i live, so i had to ask someone i know who lives in the U.S to send me some.:)
 

ben_hutcherson

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Or, if you're they DIY type, it's easy enough to make yourself.

The short procedure is to dissolve aluminum foil in potassium hydroxide. This gives you potassium aluminum hydroxide and hydrogen gas(so do it outside). You can then treat this with sulfuric acid to give you potassium aluminum sulfate, otherwise known as alum.

Since alum is relatively insoluble in cold water, but very soluble in warm water, you can then take the solid alum that forms, re-dissolve it in fresh warm water, and then let it crystalize back out to purify it.

If anyone would like to try this, I can get you a more exact procedure.
 

fuzzuki

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Yes, I did learn this in school and have worked at many places that use acid to burn out screws as well.
I have never harmed a plate using acid.
You should try it before you all knock it.
It works very fast, when gently heated.


i guess the only problem i see is that its a acid.
Did they teach you to use this in watch repair school?
You mentioned that the schooling taught you more than a person could have learned from a past generation handed down.So they told you acid is a good thing?
Very corrosive acid is, that might be why i am knocking this.
 

Kevin W.

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Thanks, but i have no desire to work with something that can harm me or what i am working on.
If you enjoy using something as caustic to work on a watch, go ahead, it,s your watch.

Out of Curiosity what was the name of the school you attended?
 
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fuzzuki

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Tell me where you learned first.


Thanks, but i have no desire to work with something that can harm me or what i am working on.
If you enjoy using something as caustic to work on a watch, go ahead, it,s your watch.

Out of Curiosity what was the name of the school you attended?
 

Kevin W.

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I dont think that is relevant, i dont wish to use sulphuric acid in watch repair.
 

Kevin W.

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I find it unlikely a school teaches hazardous repair methods to their students.
I truly don,t think this was taught at the NAWCC school.
 
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Bruce Aldo

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Another common source for alum is a styptic pencil that you use to stop bleeding from shaving nicks. I am guessing it is commonly available in Canada. It is my understanding that alum works because it sets up a galvanic reaction between the steel and brass, the steel is the sacrificial element. Can anyone confirm this? I have soaked a steel screw alone in alum solution and very little happens, but if it is in a watch plate it dissolves in a day or so.

Thanks,

Bruce Aldo
 

ben_hutcherson

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Bruce,

That's certainly a distinct possibility, and I'll give it some thought to see if I can figure out exactly what's happening. It wouldn't surprise me in the least if that's exactly what's going on.

In any case, sulfuric acid really isn't the horrible, nasty stuff that some in this thread are making it out to be. The biggest dangers relate to the fact that it's very hygroscopic , and will readily absorb water from your skin. It also gets very warm upon dilution. Both of these are not a problem if it's handled with care, and are less of a problem with battery acid since it's already somewhat dilute.

The biggest issue I see is that it has the serious potential to dissolve the brass along with the steel, especially when warmed. For that reason, I don't think it's a good idea.
 

jkamboj

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I mentioned the source of Alum in Canada in my previous post in this thread. You can find this in Indian Grocery stores, its called "Fatkari" in Punjabi and Hindi language, Fatkari is a commonly used remedy as per "Ayurveda" system of medicine.

I purchased a small pack and used it as directed, dissolved about five grams in 200 ml water. I kept the crown with broken stem inside for more than 48 hours, nothing happened, then I doubled the concentration, added about 5 gram more, after 36 hours nothing happened.

Am I doing some thing wrong, or I have the wrong salt (Alum is Hydrated Potassium aluminium sulfate).

Would some one correct me please

Jaswant Kamboj
 

jimH

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I mentioned the source of Alum in Canada in my previous post in this thread. You can find this in Indian Grocery stores, its called "Fatkari" in Punjabi and Hindi language, Fatkari is a commonly used remedy as per "Ayurveda" system of medicine.

I purchased a small pack and used it as directed, dissolved about five grams in 200 ml water. I kept the crown with broken stem inside for more than 48 hours, nothing happened, then I doubled the concentration, added about 5 gram more, after 36 hours nothing happened.

Am I doing some thing wrong, or I have the wrong salt (Alum is Hydrated Potassium aluminium sulfate).

Would some one correct me please

Jaswant Kamboj
I think that's Fitkari. Yes. Alum is hydrated potassium aluminium sulfate.

Use a completely saturated solution of Alum and apply heat to speed up the process. If it is working you should notice some bubbles forming around the steel. If you really have Alum and the stem is steel it will work.
 

jkamboj

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Thanks for the response Jim

Unfortunately, no bubbles, no reaction etc. Now I have to check it out whether or not Fatkari is alum.

Jaswant Kamboj
 

Tom McIntyre

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Your mixture did not sound like a saturated solution to me. You need enough alum for it not to dissolve completely even when the solution is warmed.

You might need as much as 20% by weight to achieve this. i.e. 4 grams of alum in 20 ml of water.

As I recall my mother used a saturated solution when pickling cucumbers but that was 65 years ago and I was not paying that much attention. :D
 

jkamboj

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Dear Tom
Your suggestion seems logical to me. I would try it in the next few days and post the progress.

Thanks for the suggestion

Jaswant Kamboj
 

ben_hutcherson

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My CRC Handbook of Chemistry and Physics lists the solubility of alum(KAl(SO4)2-12 H20) as being 11.4 grams per 100 ml in cold water. For hot water, all it says is "v s" for very soluble.

So, at 10 grams in 200 mL, you're very far off from saturated.
 

berntd

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Hello,

For all the purists here who don't want to use things from the spice rack and / or old batteries, you can always splurge out and buy:

Vissin screw removing compound from Bergeon.


Regards
Bernt
 

Clockworks999

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Will this method work to dissolve a broken stem from a stainless steel crown?
If, indeed, there is a galvanic process occurring, aren't steel and stainless steel too similar for it to work?

I wonder if winding some brass wire around the crown to act as the sacrificial element would work?
 

fuzzuki

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No, I live in Canada. There was no NAWCC shcools when I was in school.
We were also taught to use Cyanide and urine to clean watch cases.

Things were different back then.

Would you use cyanide if it was the best thing for a job?

Hazardous didn't come into play back then.
It's a different world we live in these days.

Why is it so impossible for people to believe that I was taught to use battery acid to remove rust?

It works great. If you've never tried it, how can you feel qualified to comment on it's use?




I find it unlikely a school teaches hazardous repair methods to their students.
I truly don,t think this was taught at the NAWCC school.
 

Kevin W.

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Common sense should be used in whatever you do in watch repair.
Like said earlier its your watches. Use acid if you like., and whatever else.
As far as qualified anyone who has had experiences with acid can and should comment.
I have burned holes in my clothes and i almost caused serious health problems by inhaling fumes from acid.
Why do things this way when alum can be bought off the shelf.
I prefer on a message board here to point out to people safety should come first.
 
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Scottie-TX

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SDEREK, I've used CLOROX to remove a steel screw from brass. Works great. I can't attest to the future of the brass or that it would have residual effects. I did it as an experiment. It works - just another acid like H2SO4 - a strong one. I'm sure alum works. I've never tried it but I imagine it would be very slow and safe. If you can eat pickles with it, certainly ain't very caustic.
I wouldn't try to make alum. If I could find KOH, I could as easily find alum.
KEVIN, I know all here appreciate your concern for their welfare - I do. I just doubt they'll change their opinion or procedures.
 

Kevin W.

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Scottie fully understood, i just have a little trouble getting around using or thinking of using, acid, urine and cyanide in this hobby.
Maybe i just lead a dull life.
To each his own.
 

sderek

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SDEREK, I've used CLOROX to remove a steel screw from brass. Works great. I can't attest to the future of the brass or that it would have residual effects. I did it as an experiment. It works - just another acid like H2SO4 - a strong one. I'm sure alum works. I've never tried it but I imagine it would be very slow and safe. If you can eat pickles with it, certainly ain't very caustic.
I wouldn't try to make alum. If I could find KOH, I could as easily find alum.
KEVIN, I know all here appreciate your concern for their welfare - I do. I just doubt they'll change their opinion or procedures.

Thanks Scott. I just bought some Alum. I'll have to give it a try sometime and post the results.
 
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