(🧵 cont.)
So when I posted this I was already done with the cleanup, but I'm terrible at posting 
When you're trying to remove oxides and other blemishes on metal, preferably you want a solution that attacks everything but the base metal.
Before I've used a concentrated solution of vinegar, salt and flour to create a paste that do indeed remove oxides and other ickyness. However it's not been ideal in that leaving an object too long in it causes acid damage, and it's much less controllable due to the amount of oxides or dirt differing from spot to spot. 
The new recipe which works fantastically, is a solution of citric acid, baking soda, and soap, and came to my attention from the Backyards Ballistic, who does like restoration video of antique guns. And it works! I've been scouring the webs since like last summer finding a recipe that doesn't involve overly dangerous chemicals, 2/3rds which I can't even get in Europe. 
I'd love for someone with better chemistry knowledge than me to explain why it works, but according to him it works through "chelation". My wild guess is with the right pH, the Citric acid acts as an chelating agent? 
The baking soda is just for pH adjustment as far as I know, and the soap just acts as a soap 
Getting to the point tho, all the crusty oxidation after 3 days was gone. And I got myself a surprise. During the cleaning run I was a bit worried because flakes of brass kept falling off. 
In turn I was wondering if the sollution somehow enabled a "dezincification" effect, which is the only way for brass to actually "rust".
It made me think, maybe the solution was removing material and the plates being in such bad condition that was enough for the oxidation process to rapidly start over and over.
But it was not, luckily! The reeds themselves are brass, and didn't suffer any such. Rather both reed plates were brass coated! :blobpika But the oxidation and corrosion once put in the cleaning solution revealed that the coating itself was no longer bonded properly to the base metal, which was tin! 
And that's the final clue to its age! Harmonica reed plates are normally made of brass, and sometimes steel. But tin is very much unheard of. Tin is a soft metal, and such it's not super ideal for being the base metal for riveting reeds onto that needs to stay put with abuse; after a while the rivets can loosen.
But with WWII going on, steel and brass was very expensive, with the whole war going on and all that. So as a cost saving measure, they just plated tin and called it a day!
#harmonica #munspill #munspel #mundharmonika #repair #KattWorkshop
[
] Fanged Menace 
