de-silvering process (laquer & master)

[andybee]

Here at MY45 we do mostly one step galvanics, we press directly from the so called "master".
As far as I know, de-silvering is possible, but not needed, because after some pressings,
the silver is gone ? (but I don´t know if this is correct or not).

Usually we put the nickelmaster=stamper in a acetonbath, to remove some rest of laquer.
Then we put it in a de-silvering solution, basically this is ammoniac and hydrogen peroxyde.
Usually, we put the stamper 3minutes in the desilvering solution.
At the beginning, there is strong reaction on the surface, lot of bubbles, after a while the
reaction weaker, just a few bubble. Maybe the 3minutes are too long?

When we do testpressings, there is lot of noise, especially in lead in groove.
When we skip the desilvering, the result is better.

Mossy also wrote, that it is possible, to strip off the silver from the laquer? How this works?
I searched here, but I didn´t find the desilvering process.
Any hints welcome! Thank you!

[andybee]

so, now I found an old post from chris moss:
"33% Ammonia + 33% pottasium Hydrohyde + 33% D Water mix will strip all the silver Off
Clean Nickel 100% "
But the fomula is not precise, ammonia is usually available in maximum concentration of 32% (usually 20% or 30%).
potassium Hydroxide (not hydrohyde as I suggest) is available as 99.8% powder or solutions with 20% or 40%.
but it is possibe, just to add a bit more water to get the same result...

[andybee]

no one?

[JoCrisWasGeht]

On a yellow brass surface was put a 100-200 nm thick Ag-layer.
soaked in a close recpie to the mentioned one, by you.
33 g NH3 (25%), 33 g KOH (500 g/L) und 33 g dest. Wasser.

Nothing happened.
Chemical discussion will follow - if motivated . So far: Just soaking in NH3 (25%) or KOH (50% wt)
didn't do the trick as well.




Auf eine Messingoberfläche wurde eine 100-200 nm dicke Silberschicht aufgetragen.
Rezeptur “Silberstripper“: 33 g NH3 (25%), 33 g KOH (500 g/L) und 33 g dest. Wasser.
Einlegen des silbernen Metallstücks zeigt keine Wirkung, es kehr nicht zu Messingfarbe zurück, was einem Ablößen der Silberschicht entsprechen würde.
Nun wurde das Metallobjekt in 25 % NH3 Lösung pur eingelgt. Nach 10 minuten kommt es zu Blaufärbung der Lösung. Die Silberoberfläche bleibt. Einlegen in 50%wt KOH legt auch keine Messingoberfläche frei.

[salnikov]

Hello Andy.

After the desilvering, what do you do as cleaning ?

For desilvering lacquers, we use the same desilvering solution as for stampers (father).

Cordially.