Sunday, October 29, 2006
Res Ipsa Loquitur
I have always held that every event in life - every action, every thought, every feeling - has already been played out in a movie somewhere. And if you’ve seen too many movies - like I have - then as your life unspools, the scenes of your life seem to play out as re-enactments from this or that movie.
This week, I’m blessed with playing Robert Redford’s Bob Woodward to the elusive Baboosa’s Deep Throat. Remember? Hal Holbrook’s parking garage freak? Then again, maybe I’m Dustin Hoffman in this scene. Because, unlike Woodward, I don’t know who Baboosa is. I just know he comes in the night and whispers in my ear.
“Follow the money... What’s that noise? Are you sure you weren’t followed? ” and when I look back, he’s gone.
So, this week, we’re chasing leads to see where zinc chloride takes us, and learning lots along the way. I’m reminded of a much younger - nineteen year old - Navy Guy me, with my buddy, Tee Newman, crawling around in the slippery, slimy free flood areas to inspect the Zincs while we were in dry dock. I remember not even being sure what it was we were supposed to be looking for. But Tee had inspected Zincs before. You see, Tee lived and thrived in the rarified air that the Navy reserved for screw-ups. He always got jobs like this. I was pretty new to screwing up, but I was finding it to be a comfortable, less hurried place to be. Like this Zinc job. It may have been slimy and nasty, but once we disappeared into the free flood, as far as our Chief was concerned, we were out of sight and out of mind. And to Tee’s way of thinking, out of sight and out of mind was where he planned on us staying the rest of the day.
The vague directions the Chief had given us were that if the Zincs looked too corroded, then we were to put in a work order to get them replaced. We took chisels and mallets with us to scrape and pound the white clumps off the big Zincs so we could see how much metal was left under all the corrosion.
Ah, yes. The white clumps. I remember Tee telling me, “Don’t get any of that white stuff in your eyes. It burns like a....” Well, you know. Swear like a sailor, and all that. And when we got down to it, there were lots of white clumps. Lots and lots of white clumps. It turned what I thought was going to be an easy, cruise kind of day into an itchy, scratchy, crappy kind of day that had me rethinking the merits of Screwing Up versus Doing What You’re Told.
The reason it turned into an itchy, scratchy kind of day and the reason Tee cautioned me about getting the white clumps in my eyes is because zinc chloride has a pH of anywhere from 1.8 to 4.0, depending on which Material Safety Data Sheet (MSDS) you look up. Here’s a couple I found online:
http://www.zaclon.com/pdf/zinc_chloride_granular_msds.pdf (This one says 1.8, )
http://physchem.ox.ac.uk/MSDS/ZI/zinc_chloride.html (This one says 4.0)
So, it’s either 1000 times more acidic than pool water, or 100,000 times more acidic, depending on which MSDS you believe. Tri-chlor tabs are 2.8 pH, or about 10,000 times more acidic than pool water, to give you a point of reference.
Neither of those numbers would be anything I’d want growing in my pump pots, though. It would be like putting tri-chlor tabs in the pump pot. Growing is what the zinc chloride does, by the way. As near as I can understand it, the zinc combines with the chloride and forms - you guessed it - zinc chloride crystals. The Wikipedia entry led me to the MSDS’s. The MSDS’s got me googling for zinc’s. And seeing the marine zincs made me remember that day in the free floods with Tee.
So, how do you always know where to point me, Baboosa? This goes deeper than I think, doesn’t it? Hmmm... didn’t Robert Redford say that about halfway through All The President’s Men?
Yes. Now I remember. Follow the Money. As true then as it is today. If you follow the money, you’ll see that the Big Three have dumped quite a few million dollars and staked their international reputations (read stock prices) on the success of salt systems. So, of course, they can’t admit that they, and we, have a growing problem.
I mean, I started out bitching about limestone degradation and DE filter tanks, and along the way I’ve discovered that it’s not just a little bit of a problem for a few select building materials and stainless steel.
I’ve learned that ALL METAL is at risk. And, so far, the manufacturer’s only fix for galvanic corrosion is to grow corrosive irritants in our pump pots.
I’ve learned that ALL STONE AND CONCRETE is affected. Plaster is a concrete... Right? White Portland Cement, if I’m not mistaken.
You think I’m just being dramatic? Look at this:
This is a book, Stone In Architecture, by Erhard M. Winkler, with a wealth of information about stone. I was put onto this book not by Deep Throat, I mean, Baboosa, but by a Brother From A Different Mother, whose as sick and tired as I am about hearing what a boon salt is for all of us. It would seem to me that anybody who lays stone for a living, or anybody who sells pools where somebody has laid stone, ought to have this book in their library. But if you don’t, never fear. Amazon has added a new feature, called Amazon Online Reader. So, just log in to Amazon - create an account, you don’t have to buy anything - and then, on the web page for this book, enter the term Halite into the box in the Search This Book icon. Then, when the Amazon Online Reader opens up, click on the reference to page 166 and look at the chart on that page.
What you’re looking at is a chart that shows the different crystallization pressures of different salts. Look down the list to NaCl. That’s our salt. Notice how it’s crystallization pressure is nearly twice as much as the next nearest compound? Notice how it’s as much as eleven times more than some of those compounds?
So, what does that mean? Now I may get this wrong, because like I’ve said before, I’m just a pool cleaner. And so if any of you experts in this field want to put in your two cents worth via the comments section of this blog and correct any errors, please feel free. But even pool cleaners can read, and what I get from reading the text that supports this page is that when salt enters stone or concrete in a strong enough concentration, that it will begin to crystallize, causing “crystallization expansion”, exerting pressure on that stone or concrete. It results in damage like you see in the picture that accompanies this post. That picture is of a type of stone called silver mist. It seems to be somewhere between a sandstone and a flagstone - like Pennsylvania blue - in density. That stone was put in six months before the picture was taken. And the damage done to it is called “roof jacking” which is a different phenomenon that what I’ve seen with limestone and sandstone, where they just disintegrate.
Now, lets’ go back to what those manufacturer’s reps always tell us about why all of this is impossible. We’re only putting 3,000 to 4,000 parts per million (ppm) in pools, and salt isn’t corrosive in those concentrations. And even Winkler says that you need 36 grams per 100 milliliters of water for halite to start to crystalize at temps above freezing. That’s 360 grams per liter, and that’s 360,000 ppm. So, it would appear that they have a point, right?
But most of the damage occurs where water splashes out onto the stone or concrete. The water evaporates, but the salt is left behind, inside the stone. The next splash deposits another 3,000 to 4,000 ppm. And the next. And the next. So, in about a year, you have heavily saturated stone and concrete. About 36 grams per 100 milliliters, in fact. Enough for crystallization to begin and the damage to start.
But it gets worse. Winkler also points out that at temps below freezing, NaCl crystallizes as hydrohalite. “The crystallization of hydrohalite below freezing point can much accelerate the decay process of stone surfaces... despite much lower crystallization pressures than for halite.” That’s on page 167. Read it for yourself.
So, as you can see, we don’t even have to wait for the build up of salt through splash out if we just get one good cold snap. The hydrohalite (salty water) will freeze and burst the stone from the inside out. Just like those other science guys I quoted in my very first rant on this blog:
“The most remarkable feature of salt scaling is that the damage is absent if the pool contains pure water...(and that) ...salt scaling is a consequence of the fracture behavior of ice. The stress arises from thermal expansion mismatch between ice and concrete, which puts the ice in tension as the temperature drops.”
Winkler published his book in 1994. Most of the studies he cites in his research go back to the mid sixties. But for twelve years there’s been a definitive text out there detailing exactly what would happen to ALL STONE AND CONCRETE if you mixed salt and water.
Galvanic corrosion has been a known phenomenon since 1800, when Allesandro Volta (Volta... volts... get it?) invented the first battery.
How come a pool cleaner knows about these things and the Big Three don’t?
Because if they knew about it, they would have told you before they sold you these salt systems. Right? Wouldn’t they?
Who’s got your back now?
There’s a chill in the air. Halloween’s right around the corner. Before you know it, it’ll be winter. Are you sure you want to keep pouring that salt in those pools of yours?
And Res Ipsa Loquitur? The thing speaks for itself.