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Restoring: How to make the granular silvering ?
When I did restore a Lange & Söhne movement of an "Ankerchronometer",
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I had to coated many plate parts with silver. There are literature and manuals about, but only the experience and exercise lead to success.

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One takes 6 parts (no part by weight) of iodine-free common salt and 3 parts (no part by weight) of tartar. Both is sold more or less as powder. One gives these parts to porcelain mortar and pushes it to a fine mixture powder. One selects the quantities in such a way that this mixture fills a cup or a more, then one gives that into a glass, which one can close with a cover.

One procures pure silver powder free from chlorine. One needs this powder in very small quantity, if one e.g. silvers a plate of a pocket watch.

On the one hand the mixture from salt and tartar and on the other hand silver powder one keeps separately.

The work piece plate is prepared, cleaned, degreased and finely ground. If engravings are on the plate, then these are filled out before with shellac or similarly. The lacquer must be able to be dissolved later, so that the engraving shows up again. Should the engraving remains filled out in color, e.g. at a dial, then take cold email (amateur handicraftsman shop), which gets its gloss after silvering by easy warming up again.
On filled out places or varnished surfaces no silver plating develops.

Degreasing is important! I dgrease gavanically in a chemical bath.

Silvering is to make at a place and in a place, where salt and tartar cannot cause damage, so for instance on an old wooden plate, in a cheap tub of plastic, a piece of corkboard etc.

Which we still need are distilled water (gas station) and thin rubber gloves (pharmacy). To it a small stiff bristled brush from plastic (no iron or steel bundle because of rust).

I may still refer;  we silver plates to pocket watches. If one brushes large surfaces (PP Clock dials) the quantities and the tool are accordingly largely to be selected, to be measured.

The actual procedure:

I take a quantity for instance a small cup filling from my mixture and add silver powder. Attention, only a little! A pinch of silver into the cup and I mix that properly. The silver powder is in the appearance a deep grey. If one does have mixed it in the cup one sees hardly the silver. The whole mixture remains approximately „white".

A cup with distilled water is put in the tub, a little tartar powder only tartar is also available aside. We had already put on gloves. Before us the dial lies in the tub which is sufficient large for working!  We take the brush, moisten it with distilled water, dip it into the tartar powder and rub around over the plate which becomes a little damp. The brush remains damp, the humidity must be noticeable.

Beside the tub the powder mixture stands in small quantity in a further container. There we dip the damp brush in firmly and several times, because the mixture has to stuff the brush and should stick at it. With that we rub then with firm pressure around over the plate. Everything is damp. So that it remains damp, since repeatedly the brush comes into the mixture, one can add a droplet! distilled water on the plate. During the work give the mixture time for the chemical process, for running off, which follows of course only if the humidity can work. That comes up with progress.

First the rubbing round shows no traces on the plate, one believes, but silver begins to adhere - because little silver powder was taken before -, silver tiny particles stick if one looks exactly. One can give confidently mixture with the brush to the plate, however everything must remain damp, and one must rub firmly and roundly. Success comes up of its own volition, because little silver powder was taken. The silver plating "grows" slowly over the whole plate. That one sees and controls so the roundly rubbing, so that silver grain evenly develops and no accumulations arise at the edge, against drillings etc. Also it shows up a relatively "white" Silver color, silver surface. The silver plating develops in fine grain, called frosted. Well timed is to work to be stopped, otherwise the grain amass itself and the work is for throwaway.

The more silver powder in the mixture the scruffier becomes the grain, amasses itself fast, and it develops splodgy. It does not show "white" silvery color.

Beside the plate in the tub lies remainder of the damp mixture. One can up-brush this with the brush again. For the end of the work I rub always with the brush and tartar powder damp over the plate. In the tub more and more highly liquid mass amasses, which looks more dark grey than the plate looks now. The plate is silvered and in distilled water rinsed. Bright silver marks are also under the plate.

The silver plating appears " dead -white". One will probably leave that in such a way for dials. But the whole frame, plates of pocket watches are still gilded, because the silver plating oxidizes, and should shine brilliant. So plates are brushed with a fine German silver brush. Therefore one brushes directionless completely easily over the silvered surface to give a gloss.

All the rest is experience and exercise!

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