"Ok. When are you going to paint?"
"Umm. I have to make sure it's supposed to be painted first."
"And you'll do that ... ?"
So, this weekend I dug through several websites, and eventually concluded that, yes, the quick-dry cement is paintable. Well, preferably, you coat it with masonry waterproof sealant, but I was just going to use the paint I'd bought back in December. Saturday night I scrubbed the cement so I'd have a clean surface to paint, and last night I cracked open the paint can. Which had the thick, goopy consistency of sludge. "This is paint?" I checked the can. No, it's masonry waterproof sealant. Hey, bonus!
I lathered it on, trying to keep a fairly thin coat, over the cement I laid down in January. There was one spot in the south wall where a tiny bit of moisture was coming through. Not even an actual trickle; just enough to get the paint wet there. I'd been planning to chisel it up and patch over it, but after my last round of patching, I'd lost all enthusiasm for that. The masonry waterproofer warned "not warrantied for use over paint", but I figured I'd slather some of it over the problem spot and call it done anyway. There was so little moisture coming through that I couldn't even tell where the actual leak was, or if there even still was one. I coated that spot, along with the rest of the patches, and left it to dry over night.
It's only supposed to take 3 hours to dry, so I reasoned 24 hours would be plenty of time. I went downstairs today to apply the second coat.
And found that the one spot I'd applied the waterproofer over paint was leaking. Copiously. Apparently, when it says "not warrantied for use over paint" what it means is "chemically reacts with paint to destroy any sealant properties normally possessed by either compound". O.o It was funny, in a way. Apart from breaking my multiple-weeks-without-a-leak record in my basement.
At least I could tell where the problem spot was now.
I chiseled away most of the sealant/paint/cement currently over that section of floor, stuffed in a fresh batch of cement, and am leaving it to dry now. Compared to the deluge I was getting before, this was nothing, though. I didn't even need to crouch with both hands over the quick-dry cement blob for five mintues, trying to keep water and cement from leaking out of it before it had time to set. I checked on it after an hour, and it didn't seem to be leaking anymore; I'm not sure I managed to fix any of the other leaks in one layer, so that'd be a record, too. I'll probably put off doing the rest of the sealant for a few more days, though, and give the new patch plenty of time to completely dry and set.
In other news: remember how I said that the previous job on the floor consisted of layers of paint, cement, and some other substance I couldn't identify? Now I can identify it: it was masonry waterproof sealant.
So ... um. Now that I've determined that everything I've used to try to fix my leaky basement has already been tried, to no avail, I must fall back on the idea that somehow, I will have done this better than previous handymen.
Wish me luck, everyone.