Dissolving a stem that cannot be removed from the crown

[Francisco]

First, I would like to thank all the forum members that helped me to discover this technique.

Some times the stem may break itself in the way that following picture shows:

As seen, there is no enough room to take the stem and to unscrew it from the crown. Therefore, it seems impossible to remove the stem. Hence, a new stem should be bought, what could be sometimes very expensive.

In other cases, it is possible to unscrew the stem, but the rest of the stem is too short and the stem is expensive or spares are not available. In such cases, if the broken part is the threaded part, a stem extensor can be used. Next picture shows a stem extensor.

The broken stem would be screwed in the small tube. However, in our case, a stem extensor is not useful, as we cannot remove the broken stem form the crown.

What we are going to do is to dissolve the stem. This is possible because crown is made of a material much more resistant to corrosion than the stem.

To dissolve the stem we will use alum powder. If you cannot find it in a local store, it can be easily found at Ebay. Follows one example:

I bought this one:

We put quite alum powder in a small glass.

Really, I did put twice quantity than the picture shows. The alum powder is dissolved in water.

The crown is submerged in the water. Moreover, I added an old stem to see the effect of the alum powder on it.<o><br />

This is a very slow process. The time needed depends, of course, of the amount of stem to be dissolved. I recommend shaking the glass every couple of days.<o><br />

In this case, as I wanted to see the effect on the old stem, I wait quite a long time. Last picture was taken after 9 days. It is possible to see small pieces of the stem on the bottom of the glass.<o><br />

Alter two weeks, the crown is free of the piece of the stem. In addition, the old stem shows this horrific aspect. Please check that one part of the stem is open.

Now it is time to check whether the hole of the crown is truly free of small pieces from the stem, and if a new stem can be screwed. It seems so:

As next picture shows, there is no any problem to screw a new stem. Therefore, the crown has been repaired.<o><br />

Thanks for reading,

Francisco

[Logan]

Great tutorial thanks.

Another trick I use is nail clippers !! The sharp blades and the blade shape often allow then to grip even if only a tiny amount of the broken part is protruding.

[Toadtorrent]

Great write up. I've seen the posts talking about alum powder...but this illustrated version is tops.

[Samurai]

Very nice. Thanks for the pics

[Francisco]

I have been told that heating the water reduces a lot the time to dissolve the stem.... take into account.

[dluddy]

Another great post confirming the legend.....Thanks for sharing Francisco

[Member X]

Thanks for another great guide

[Slartibartfast]

Great tip. I would never have thought of this.

Thanks!

[FxrAndy]

Thanks Fransico, I to had read about this but not had need to use it yet, but thanks for show in the proof

[Rolexman]

Great write up thanks! Is that your Oris crown?

[Guest avitt]

Alum also works to remove broken taps...not that anyone would ever have the need to do that

[Francisco]

Great write up thanks! Is that your Oris crown?

Yes, it was.

However the thread was too damaged and I bought the gen Oris crown for my Carlos Coste. I chaned the tube... and now works perfectly...

[vlydog]

magnifico

[kronos twin]

Is this material dangerous to dispose of?

[Jkay]

Alum is used in food. It's not dangerous at all.

[sander]

I have no need for it right now but I just ordered some because you never know!

Great tip!