A correction to what is posted there:
1. Fill a milk bottle cap or other small container with salt, and add a few drops of distilled water - NOT enough to dissolve the salt, just enough to moisten it. You want the slurry to be thick and pasty.
This is not correct. You want a saturated salt solution. That is all. You WILL dissolve salt, a bit more than 25% w/v. If you use too little water it will take too long to reach equilibrium.
I use a shot glass of saturated salt solution in a small tupperware. The best way to do this is to take a bit of water, maybe 1/2 shot glass full, and add salt until no more will dissolve, and you have excess salt on the bottom of the glass. If you leave this overnight and still see salt on the bottom you can be assured it is saturated. Put this with the hygrometer in a small tupper or ziplock and you're good to go. Talk about thick paste and few drops of water is misleading, I think what he means is not enough to dissolve ALL of the salt ... but the amount of water should not be so little to not allow rapid equilibrium inside the closed container. The rest of the page on the thread linked above is correct.
