Here are the results of an informal experiment I conducted to test the Caswell silver brush plating technique.
I started with a 1/4" square brass rod 8" long and buffed each side to a deep shine. The rod was then degreased by first wiping with alcohol and then rubbing with a rag soaked in tolulene solvent. A scratch was made in the center of the bar denoting right and left sides and the letters A,B,C,D were etched to label each surface.
The Preparation
A left was plated 1 minute, one wand stroke per second, cleaned and polished and left as is.
B left was plated 1 minute, one wand stroke per second, cleaned and polished and then treated with MAAS metal protector.
C left was plated 1 minute, one wand stroke per second, cleaned and polished and then given a coating of Carnauba wax.
D left was plated 1 minute, one wand stroke per second, cleaned and polished and then treated with MAAS metal protector followed by a coating of Carnauba wax.
A right was plated 2 minutes, one wand stroke per second, re-dipping the wand in solution after 1 min, cleaned and polished and left as is.
B right was plated 2 minutes, one wand stroke per second, stopping to clean and polish after each minute's plating and using fresh solution and left as is.
C right was plated 4 minutes, one wand stroke per second, re-dipping the wand in solution after each minute, cleaned and polished and left as is.
D right was plated 4 minutes, one wand stroke per second stopping to clean and polish after each minute's plating and using fresh solution each time then left as is.
The finger test
Rubbing the left side (1 minute's plating) A,B,C,D back and forth 250 times with the finger using moderate pressure produced
no perceptible change in the silver plating on any of the surfaces. Since the single plated left side showed no perceptible change in the plating after rubbing with the finger the multiple plated sides were not tested.
A more aggressive test was then used to determine the thickness and/or durability of the brush silver plating comparing the different times and methods of application. Next all sides were polished with Wenol metal polish on a soft cloth stopping to observe the finish after every 50 back and forth strokes with moderate pressure. The Wenol tube is marked "not recommended for plated metals".
The metal polish test
After 50 back and forth strokes
All 1 minute coated left sides had significant brass showing through so no further testing was done.
All multiple minute coated right sides showed no perceptible change.
After 100 back and forth strokes
All multiple coated sides had very slight brass showing through on the corners of the bar.
After 150 back and forth strokes
A right had significant brass showing through.
B right had some brass showing through, but was better than A.
C right had some brass showing through similar to B.
D right had a very small amount of brass showing through.
Conclusions
1. It appears that the longer you plate using the wand, the thicker and more durable the plating, but after 2 minutes there are diminishing returns on the time and effort.
2. Cleaning and polishing between 1 minute applications seems to slightly improve the coating process.
3. One should never use a metal polish not recommended for plated metals on silver plating.
4. The use of Carnauba wax to help extend the plating life of brush plated keys that get excessive wear shows promise, but could not be confirmed by this study.