Basement Laundry, Part II: What a Floor Wants

Ambrose laid down the pen, and because the floor sloped where the house had settled, it rolled down the table, and down the floor-boards and under the mahogany sideboard, and lay there among napkin rings and small coins and corks and the sweepings of half a century.
Evelyn Waugh, Put Out More Flags

Do you know how much filth can work its clever way into the pores of a basement concrete floor over sixty or so years? Well, yesterday, I found out.

Just scratching the surface (literally).

Over the last week, I've been working on finishing the basement laundry room. One part of that project is to paint the concrete floor with a grey garage floor paint. Simple, right? Well, yeah. But also very dirty.

I figured I could clean the floor, on Monday. Let it dry overnight with a space heater warming up the place, then on Tuesday, fill the holes (there's a ~4" diameter, 2" deep hole in the center of the floor where a post once was) and shop-vac the floor again, then Wedenesday I expected to be able to acid etch the concrete and paint the floor....

Well, things never go as planned. Monday, with the help of Hyeseung, we cleaned the whole room. I shop-vac-ed the floor, then mopped it and shop-vac-ed it again. I put a space heater in the room to help it dry and to hopefully bring the space up to painting temperature. Tuesday I filled the big hole in the middle of the floor, and shop-vac-ed again. Wednesday, the hole patch was not yet the color I was expecting, so I postponed the acid prep and painting, but I did mop the rest of the floor again and shop-vac again.

Yesterday I got down to the nitty gritty, the serious floor cleaning. On the floor with scraper in hand, I clawed and dug and forced out all the history that was hiding wedged under moldings, thresholds, and wall framing members.

I found that at these locations, along most of the walls, were remnants of some kind of paper insulation/underlayment for some kind of flooring:

My first thought was, "Did they have carpeting down here!?" But then I took a closer look at certain patches stubborn adhesive that spot the concrete here and there:

And I realized, I've seen this MO before.

Throughout this house, in the locations that have finished floors that are not hardwood, there is some kind of plastic flooring. I would call it vinyl, but I don't think that's quite right. The 1st floor kitchen has it. A couple of the bathrooms have it, as well as the top floor kitchenette. (I'll post floor plans soon.)

In order to finish the one bathroom that we now do have finished, I ripped up the plastic floor (and found hard wood beneath). It took about 10-12 hours of scraping to get the floor up off the wood:

I'm really glad I didn't find myself with the task of removing this flooring in the basement. I think a flood is probably what did the job, or precipitated the doing the job anyway.  At some point in this house's recent history, the basement must have held standing water, about 4 to six inches deep. Here's a shot of what the bottom edge of a typical portion of panelling in the basement looks like:

Yummy!

So, back to the scraping. I scraped and swept and repeated until I couldn't find anything more to scrape. Then I vacuumed. Then I mopped the floor again. Now, I figured, it's ready for etching. This was at about 11am yesterday. So I put on galoshes and my Mr Clean Nyplex gloves. I tracked down a respirator and my eye shields. I mixed 1 lb of sulfamic acid etcher with a gallon of hot water in a standard water jug, capped it and poked some holes in the top plastic to fashion a "watering can", and I doused the floor in acid.

As the acid hits the floor, it sort of foams and makes that classic horror movie acid dissolving sound. HISSSSS..... and fizzles to nothing. It's like putting hydrogen peroxide on a wound, only not painful and much more dramatic. It was, in a word, neat.

So, then I let it sit for about 10 minutes, after which I started scrubbing. That's when the filth's full battalion  emerged from every hiding space, every pore, to defend the status quo:

Scrub tracks in the war against grime.

Sure, the dirt seemed to be coming out of nowhere, and sure it seemed to be releasing into the acid water solution, but how the heck was I supposed to get all of this dirt up? Well, I followed directions, skeptically, and everything worked out great.

In the end, I power-washed the filth army to oblivion, with a layover in a wet vac. Power-washing is super satisfying. All told, in the course of power-washing those 40 or so square feet, I filled our shop-vac about twenty times. Which means I sucked up somewhere around 100 gallons of black, and later grey, and later clear, water. Thank the lord there was a toilet in that room.

The acid etching revealed some pretty large cracks in the concrete, and I also had to touch up that hole patch I had mentioned. I am wondering if the paint we have will span the cracks, or if I need to go buy some kind of filler and let that set. I am using a two-part water-based epoxy paint, designed for garage floors. It seems fairly robust, but can it span an eighth inch crack?

If you got ideas, please let me know. I'm going to go downstairs and see if the place is dry yet. And shop-vac some more, of course.