Very nice job there - simple but effective! :thmbsp:
I use a VPI machine, now with the addition of a steaming step (Walgreens steamer), and for really dirty (or any moldy) finds I'll do a sink-wash first, but I still agree with your approach on several fundamentals. I like to apply the fluid and brush first without the motor running, coordinating the platter and brush movements by hand, as you describe.
I also use another mat for the "clean side", after doing the first side using the original "dirty" cork mat that came with the machine.
Similarly, I use a second vauum-head for the rinse cycle, so that any contaminants picked up by the velvet strips on the first (cleaning) go-round won't be re-deposited on the second (rinse) cycle. This adds the expense of a second head, but the increased peace-of-mind for a semi-perfectionist is worth it.
I'm intrigued by your use of the pads to suck up most of the liquid and grunge first, before vacuuming. I've occasionally tried using things to blot up some solution, but mostly just let the VPI suck it all up, but your approach --while costing more in used pads-- might help keep the pads on the vacuum nozzle from getting as dirty, as quickly. Then again, I wonder if there is a chance of the pad pushing some of the dislodged grunge back down into the grooves?
Also, you said that you turned the platter about eight times with the vacuum, and then still left the record to air-dry after the process. Do you still detect moisture after the vacuuming? If so, that sounds to me like perhaps your vacuum isn't doing a very good job of sucking up the liquid. My LPs usually get DRY after just 2-3 revolutions on the VPI. If they look wet, it's only the like-new shine of clean vinyl. The difference might be due to the level of contact, the material (paint-pads vs. velvet), the degree of suction, the closeness of contact, or other factors. One guy (who sells a competing wet product) says that the VPI sucks TOO fast, leaving some dry residue behind, but I can't detect any of that happening.
Here's a suggestion: You might cut a disc of rubber or similar material, just barely bigger than the size of a record label. Lay it down over the record label before clamping it (or else cut a "doughnut" ring of rubber material that fits around the clamp, and put it down around the clamp, after clamping). You could add a thin but stiff backing to this, if you wish. This extra disk/ring will help prevent any water that spills over onto the label area (despite your efforts to prevent it) from affecting the label. Most labels are fairly resistant to minor/brief contact with water, but why take more chances than necessary?
Again, nice job there, and thanks for taking time to photograph and explain it so well! :thmbsp: