No surfactants. Wetting agent. In everyday lingo what is referred to as surfactants defines compounds meant to cling to the surface discouraging further contamination, while pure wetting agent simply allows the (cleaning) solution to flow between the surface and the contamination helping the brush/suction take the contamination out.
Stylus of course doesn't know surfactant from plain dirt so it will sound like dirt and it will collect it from the groove and fuse it onto itself. Oh joy.
Isopropyl alc has marginally lower surface tension than water, so it mostly does the job (ratio: about 1/10 of the solution by volume - 1 part Isopropyl, 9 parts distilled water from the pharmacy
Will it magically remove the braai fingermarks from the vinyl or years of slowly fused airborne pollution? No, not even close. But, it helps (in combination with "solvent"), plus it leaves no residue and most importantly it helps the solution evaporate faster. Good stuff.
Any detergent is a wetting agent too as well as solvent for most contaminants. Unfortunately, 99.99% of detergents contain surfactants (and gawd knows what else - some are more primitive than the other) which WILL
leave gunky residue in the groove. Sunlight is a prime example - even one tiny drop of it per 1/2L of the solution leaves enough residue that your stylus will gunk-up after playing 4 LP sides.
Kleen Green is different from other common household detergents and seems to be the right(est) answer to our needs.
It works perfectly fine for me and a few more people here and I am yet to detect any residue from it.
About 10 fat drops per 1/2L of solution is my ratio.
If you are after the best in wetting agents, Ilford's ILFOTOL is apparently the current favourite.
Kodak's Photoflo has been used by many for a number of years but I heard recently that it actually does contain surfactants thus, rather not.
Back to the article; I have no reason not to believe that Tergitol NP-9 is "it" so ask your wife if she can get you some "nonylphenol ethoxylate NP-9" and then SHARE!
If you encounter one (or more) of those pesky permanently crackly LPs that appear perfectly clean after the wash & vac but still carry on crackling, you are most likely looking into one of those that somehow ended up with finest inorganic dust sediments in the groove which was then burnished into the vinyl by repeated playback without cleaning it first. No amount of any of the above cleaning solutions will help with that.
But...! Simple white vinegar often will. It dissolves or at last loosens the inorganic material. 3-5 minutes of vinegar treatment (agitate it with brush, just like normal cleaning process) followed by suction and than a normal cleaning solution & vacuum WILL make a noticeable difference.