If you want to make real Colloidal Silver and know what PPM you made, you NEED a current limiter. 27V and a resistor is not going to do it. Without constant current (which you won't get), you have no clue what you made.
Read the articles and follow what they say. These are time tested, true procedures for doing it properly. There is no "cutting any corner" here.
Also too, the current you need to use is rather small. For silver wire, 5-10ma tops. For a silver bullion bar, 15-20ma and as I said, it must be constant current. This is the only way Faraday's law of electrolysis works. There is no other way to determine the PPM of your result. There is no meter you can buy to measure it. Constant current and proper cell voltage and time based on Faraday's law of electrolysis is the only way to do it properly.
All reducers require you heat the IS solution to maybe 120F+ degrees. They reduce extremely slowly if even at all at room temp. Even at 120F they can take a while.
The purpose of the sodium carbonate is to reduce the resistance of the water so you can get reasonably good current through the cell. It has a couple other purposes. Your cell is an electroplating cell. Without the sodium carbonate electrolyte, the silver ions you draw off the anode into the water would immediately plate-out on the cathode. This would render IS production worthless as you wouldn't make any. The electrolyte interferes with the silver plating out on the cathode where now you can build up the PPM in solution so when you reduce you actually get a reasonable PPM. The sodium carbonate also raises the PH of the solution to around 8-8.5PH (alkaline). Reducers are sugars (glucose, maltodextrin,...) and they only work and reduce in an alkaline environment.
You really need to reread the articles and study them and BELIEVE what they say. If you don't follow the procedure properly, there's no clue what you made and no way to measure it.