Yesterday I pressure washed a couple records. It was fun. My theory is that traditional record cleaning techniques don't put much kinetic energy into the groove. Bristles are too thick to go into the groove, or if thin enough they are too soft to scrub. I think that the reason vacuuming is superior to towel drying is that the vacuum imparts kinetic energy to the liquid providing a weak scrubbing action for a very short time, but enough to make a difference when combined with surfactants and solvents. I wondered how much improvement a sustained high kinetic energy scrub from harmless water molecules would yield.
My PW is 5HP ~2000psi machine, I used a 25 degree green tip, about 4 inches from the record surface, so there was probably about 1000psi actually hitting the record grooves. It is enough power to remove mold and grime from my white PVC lawn furniture. I hold the nozzle 1/2" from those chairs and it does no damage. So I figure, what the heck?
I started with the PW wand about 2 feet away and looked at the shiny surfaces of the record for damage before getting incrementally closer. Finally got down to 4 inches distance and shiny surfaces on the LP gutter remained perfectly shiny, so the water is not damaging the record. How could it? I assume that a red zero degree tip would damage the vinyl if held up close, as it would damage vinyl siding when used with a professional 3000psi PW.
I had to build a contraption to hold the record securely for PW. Placed on the ground, the PW overspray at the edges was strong enough to clean the driveway concrete around it. But driveway dirt is nothing compared to dried mold and bacteria.
How did it work? Subjectively it sounded noticeably better. Even blasting with the Bulls-Eye hose nozzle on the 80psi hose made a noticeable improvement. Blasting the grooves with 80psi water makes it quieter and cleaner sounding, lower noisefloor. But some ticks and pops remain, so the pressure had to go up. I'm not yet sure whether additional pressure made any noticeable improvement.
I recorded the playback signal of each record before and after pressure washing. I will analyze these and report. I did see that some of the tick transients visible on the waveform were removed by PW, but that was expected.
Subjective opinion on the change is that pressure washing/hose blasting does make the records cleaner (duh) and reduces low level noise floor, makes the record sound louder. There was some evidence of it actually being significantly louder, but I have to test that more carefully to rule out testing error. Some ticks remain, although there is no evidence of visible scratches on the record surface. Maybe a chemical pre-treat will improve the PW cleaning further.
