Another easy way to restore ID plates is to simply use a cheap brush plater which are available on line.
http://www.ebay.com/itm/Plug-N-Plate-Ni ... 536wt_1192
You can use this plating system on many of your smaller phonograph parts during a restoration project also.
First clean the plate and give the entire plate a coat of black lacquer not too heavy just an even coat.
Once the plate has dried completely, put a little rubbing compound and water on a perfectly flat surface, (I like to use a small piece of glass). Now with the face of the ID plate down, slide the plate around pushing the plate down into the compound using an even pressure. The use of a small piece of wood a bit smaller then the plate size will help keep an even downward pressure but it is not necessary..
The point here is to remove the lacquer from all the high points on the plate and soon you will start to see raw brass.
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These high points are the part that are to be plated in the next step. ***
You can occasionally wash the plate off and check your progress to make sure you removed all the lacquer in the proper areas. You can also use a Q-tip dipped in some compound to do some of the fine detail work if needed but don't get too picky. Keep in mind what the plate looked like before you started and also the fact that it's 100 years old.
It might sound a little complicated but it is really easy.
If you do rub too hard you might get into the black background but it's easy to correct. Just thoroughly dry the plate, shoot some more lacquer on it and start the sanding/lacquer removing process over again.
Once you are happy with the piece, all the high areas should be a shiny bright brass.
Make sure the plate is clean & dry and try not to touch the plating surfaces with your fingers as you could have some natural oil on your hand. Hold it by the edges or use rubber gloves.
Now hook up the the plating pad or brush with the wires and alligator clips provided. The power supply can be a couple of 1 ½ volt batteries if you like but most kits come with a 4 ½ volt plugin power supply.
The positive lead goes on the brush and the negative lead clips onto the plate..(be careful not to scratch the plate).
HERE'S THE FUN PART
Now wet the pad/brush with the the nickel solution and using a slight pressure apply it to the plate. Always keep the pad/brush moving and don't stay in one spot too long. Keep moving the pad/brush around the plate with the solution on it. The soluction will not hurt the black lacquer finish but try to concentrate on the exposed brass details.
Thats it,, right before you eye you will see the nickel transfer to your ID plate in just the places that you want it. The whole process will take you less then an hour..
I have used it many times and have had great success with it.
fmblizz