Posted by Kenneth Sloan on December 17, 2003 at 15:53:34:
Yesterday's UPS truck brought my Caswell Silver Plating kit. It consists of a DC convertor, wires leading to two small alligator clips, a "wand" consisting of a metal "spatula" with an insulated handle, and a bottle of silver solution.
This was a "middle-of-the-road" choice. Caswell offers a "wipe it on" product which does not use electricity. On the other hand, they say "theoretically, you can plate silver onto brass, but we recommend that you lay down a layer of nickel, first" - and of course offer a kit which contains all sorts of metals in solution. I decided to experiment with the silver-only kit, just to see how it went.
I have several different types of flaws in my silver plating. Yesterday I tried the kit on two of these.
First, on the guard for the bottom bow, I had a worn spot with an appearance best described as "yellow stain". It was perfectly smooth to the touch, but simply "not silver". When I first noticed it, I was sure it *was* a stain - but cleaning, rubbing, polishing...just made it a brighter yellow.
Finding a spot for the alligator clip was a minor challenge - I settled on the strap ring. Following directions carefully, I brushed...and brushed...and brushed...with minimal effect. After awhile I wiped away the mess and gave a quick rub (using old "silver polish gloves" that were just laying about). Definitely a change - but I could still see the scar. After a second, and then a third go...perfection! After cleanup, the "yellow stain" is completely invisible. Of course, since this is on the very bottom of the bottom bow, I don't really expect this touch up to last very long. If nothing else, it will probably regress the next time the tuba is professionally cleaned.
Encouraged, I moved on to a tougher problem. This was a dime-sized "fleck" on the throat just below the path of the leadpipe. Here, you could clearly see that a small patchh of silver plate had simply flaked off. Where the previous flaw was clearly due to wear - this spot had sharp edges. But, the total area of the "unsilvered" patch was similar to the wear spot on the bottom bow.
I tried...really I did - but my technique clearly lacked something (and here is where I solicit advice from the pros). I did lay down a considerable amount of silver, and definitely "softened" the edges of the spot - but what I now have looks like a very dark elliptical region (generally covering the original scar) surrounded by a bright ring. The dark spot looks mostly like a very thin layer of tarnished silver. The bright ring is more silvery...but it has a very different character than the surrounding original finish. The "silver plating" appears functional...but the spot now looks like someone put out a cigar on the spot - a nice, smooth, dark elliptical blob.
Admissions of guilt: I probably did not do enough surface prep. Essentially, I gave both spots a good rubdown with the "silver polish" gloves - but nothing in the way of detergent and certainly nothing in the way of "polishing to a bright shine".
I expect that I'll have another go at this spot in a few days, to see if repeated application can build up the plating - but I don't have much hope that the spot can be made "invisible" in the same way that the stain on the bottom bow was.
For the long term, I have this 2"x3" (mailing label sized) "yellow stain" on the inside of the bell. The appearance of this flaw is a lot like the one on the bottom bow, so I'm encouraged that I might make it disappear - but I think that in this location I'd rather leave it alone rather than risk the result that I got with the dime-sized fleck.
So...advice, please. Any tips on re-plating technique? Any advice on surface prep?