I copied this post, as I found it to be very well thought out. (I hope you don't mind)
Thanks for the help deme, this plastic knife in my back was starting to hurt....lol.
Joined: 18-March 08
Member No.: 15,005
I'll post this here as well.
Not to stir the pot but it may...
pouring anything down the drain goes to the same place in most states. Your local POTW (privately owned treatment works).
And gets treated before being reused or sent to the sewer. So if you pour vinegar down your household drain it goes to the same place as OX would. They would both be treated the same (as they are both acids). The POTW could care less if you dumped 15-20 gal of dilute OX or vinegar down the drain as long as it doesn't contain lead, copper, nickel, chromium, silver, or cadmium. This is what you should be worried about when cleaning metal with vinegar or OX.
but that ok I did the leg work already. Cleaning a chrome frame in OX yielded:
ND= non detect by my atomic absorption machine which is accurate to 0.001 ppm
I cant imagine vinegar yielding any different results.
Now that 20 gals that your poured down the drain gets diluted 1000x over by everything else sent down the drain by everyone in that POTW's service area.
Both Vinegar and OX should be neutralized before disposal. Seeing as they have almost the same pH (1.1 for vinegar and 1.3 for OX when in liquid)
Now is OX more toxic to you or your family? YES and NO
If used correctly with the proper PPE it is a very low risk chemical.
If I had a choice between vinegar or OX I would use OX. But that's just me.
Most metal resto/finishing shops now use Sulfamic acid. for rust removal and cleaning. Its less odours that both OX and vinegar about as harmful as vinegar and much less reactive.
Sulfamic is in most of your houshold descalers or lime removers as well.
This is what I use solely (sulfamic) the bath I currently have has been working for 4 months. Takes about half the time to clean a frame than vinegar and doesn't stink either.
I have access to pure sulfamic acid powder i use 4 lbs to about 15 gas of water. Which gives you about .44% by weight for the total bath.
You may be able to get this through your local chemical supplier. Or if your in the so cal area hit me up i can get ya some.
When running a tank of OX i used 1 gal wood bleach to 15 gal of water. Much more cost effective than using pure vinegar for big parts.
And if your wondering I work for a water treatment/metal finishing/plating shop.
Great post man!
I believe sulfamic was among the items that were suspected of being in the product "evapo-rust" in a thread a couple of years ago (and mentioned on page one here), along with vinegar, and other key suspects. And yes, there are indeed other things that will work. But the best results, and best bang for the buck, are king.
I do want to point out a few things that could be very confusing about that posting as well though.
First, this thread focuses on using OA crystals. Deme's mixture of 1 gallon of "premixed OA deck cleaning solution in liquid form" to 15 gallons of water could be very confusing here. Using 1 gallon of "pure OA crystals" to 15 gallons of water would yield a wicked potent mixture. A very dangerous mixture even. So lest ye readers not get the two confused! He was talking about pre-diluted OA in a bottle, NOT pure crystals.
Second, I believe your pH numbers are technically correct for Oxalic Acid, as well as for Vinegar, however I think that those numbers are very confusing, and misleading to most people here. Those look like numbers from an MSDS. Which are very much incorrect in what we are doing here.
So, not to prove anything, but to make sure people don't get mislead, or hurt, or otherwise, I will share more of what I know, and why and where these things get misleading.
(Please, anyone in the KNOW, who may shed light to any errors here, please feel free to set the record straight!)
I've been trained in the use of MSDS's once or twice a year for about 16 years. MSDS (Material Safety Data Sheets) have "Safety" as the cloak they wear. And it's kinda true. However, it's far more complicated than that.
In an age where new chemicals are being born at a rate never seen before in mankind's history, the government needed a place to start keeping track of them all, to protect humanity in general (in the big picture), they are doing so by forcing disclosure. Their actual use in practice is far more complicated than that now.
Because of forced disclosure....Science finds them handy for knowledge. Science finds them handy for discovery. Businessmen hire scientists to take the information in them and steal it for profit....Employees find it handy to discover what their employer's are killing them with. Employees find them handy to use to force employers to take steps to prevent having the chemicals kill them (such as providing protective equipment, ventilation, etc) . Employees have found them useful to use in court to sue employers for.... Etc...
Also they give emergency medical technicians the ability to diagnose, evaluate, and treat chemical injuries, illnesses, threats, burns, etc...
They give fire departments the ability to assess chemical threats, and allow them to train, and ultimately safely battle fires involving chemicals.
They give the EPA information on how chemicals may affect the environment...
In short, they are designed to be INDUSTRIAL documents, not "over the counter" back yard remedies. Just like medical journals, and Physician's Desk References (PDR), in the hands of your average Joe, they only lead to misdiagnosis.
Also, in the hands of corporations who don't want to disclose their secret formulas, they tend to be "bent" to their liking as much as possible.
But there are certain standards that must be complied with when generating them. Some can be bent, some can be broken, and some are usually not worth bending, so they are accurate.
I "BELIEVE" that the standard for measuring the pH of a chemical for the purpose of an MSDS, is to measure it at the ABSOLUTE WORST it can be. Chemistry 101. Mixing crystals in water. There are unsaturated mixtures, saturated mixtures, and supersaturated mixtures. A saturated mixture is when water is at a standard temperature (70 degrees F??) and you add as many crystals as you can dissolve in water. If you take a cup of water, and dissolve as much sugar as you can in it, eventually you will get to a point where it just will not dissolve any more, and it will just lay on the bottom. That is a saturated mixture.
If you cool the water it will hold less of them, if you heat the water it will hold more. If you heat the water, and then saturate it, and then cool it, it will become supersaturated.
If you only add a pinch of crystals to the water, it is grossly under-saturated.
So if any meaningful information is to come of a "Standard" or from an MSDS, everyone has to do it the same. In the name of safety, a "Worst case scenario" is desirable. If a truck load of Oxalic Acid tips over and it is raining, just exactly how powerful can that mixture be when someone comes into contact with it?
Therefore, I BELIEVE ALL MSDS measurements on "PURE" chemicals are done at "Saturated Mixtures". It represents HOW BAD it CAN get, so the firemen, EMTs, and workers in the factory know what to do, and how hazardous it can be if things get out of control. This does NOT apply to premixed solutions that are being marketed and branded. IOW toilet bowl cleaner brand "X" may have Oxalic Acid as the primary ingredient, but it is diluted to a pH of "whatever", "as is".
So.... the numbers above, stating a pH of 1.1, and a pH of 1.3 are the absolute worst it can be at complete saturation of the chemical.
What does this all mean exactly?
For starters, we are using a very unsaturated mixture of Oxalic Acid to clean our bike parts. We are only adding "a pinch" of crystals, to a "lot" of water. We are by no means dissolving as much of they crystals that will physically dissolve in the water.
A pH refresher course (Power of Hydrogen). Distilled water is neutral. Neutral is a 7 on the pH scale. As the numbers get lower, the mixture is more ACIDIC. As the numbers go up, the mixture is more BASIC, or ALKALINE.
An important thing to understand is that the scale is logarithmic. This means that for every number away from 7 (neutral) the jump is 10 times greater! So, 8 is ten times more potent than 7, 9 is 100 times more potent than 7, 10 is 1000 times more potent than at 7. So by the time you get near the ends of the scales, you are messing with some REALLY nasty stuff!
Here is the reality of what we are doing. Our tap water is usually between a pH of about 7.5 to 8. (ballpark). It is usually fairly hard water, and contains lots of calcium and such. Sea water is almost always around 8.4 because of the salt. ( I have done a LOT of stuff with aquaria, and I am pretty good with water conditions of the tap, and what is in the lakes, and seas, etc..)
So, assuming my tap water is at 7.5, If I start adding some OA crystals to my tap water, it will start becoming more acidic. But we are starting with water that is alkaline, so the first few pinches of OA crystals will only bring the water to a pH of 7 or neutral pH which is what distilled water is. I have to add more crystals to actually tip it to the acid side of the scales.
Being that we are only adding a few ounces of crystals to a gallon of water, we are not going anywhere near a pH of 1.3! I have never measured one of my mixtures of OA, (though now I may do so sometime) but I can always put my hands in it, and the worst damage I incur is some mild stinging in open wounds. Much like the stinging of orange juice in a hangnail, only not quite as bad.
So, without taking any actual pH measurements, my best guess as to what the pH is of the mixtures we are using would be a little less than orange juice. Maybe a 3 to a 4 on the pH scale (It would be interesting to know for sure, but I think I'm close, and I am out of pH testing chemicals) . Vinegar as it is marketed, is about a 2.
If you were to use "premixed deck cleaner", the bottle may be premixed to a pH of 2, and then diluting it with 15 gallons of water, may bring it to a 3 or 4. (I am only guesstimating here).
So, the OA mixtures we use are very mild, and take very little to bring the solution back to a neutral condition. In fact, after it is used in the bath, and after it starts reacting with things in your pipes such as calcium deposits, it is probably almost neutral by the time it hits the street pipes! I don't sell the stuff, I'm not in it for the money, I'm just telling it like it is to the best of my ability, and not wanting anyone to get confused nor hurt by having no clue about what we are mixing up here.
If we were in fact dealing with an actual pH of 1.3, that would be almost 1 million times more potent than neutral! Indeed, that is the cartoon mixture that can dissolve the spoon mixing it! lol. That could do some damage, for real. The danger increases exponentially at the ends of the scales. The old saying, watch that last step, is a big one!
Enough science for one day. lol.
As for price....One still can't call this procedure "expensive" as it was argued.
Page 9 spelled out the last price I paid for OA crystals.
$3.91 USD per pound of pure OA crystals (16 ounces), shipped (to the US). (It would be less than half of that price if you picked it up, and didn't have to pay more than the price of the OA in shipping and handling!)
16 ounces will mix about 5 gallons of water (or more) of the mixture concentrations we need to do our parts.
I don't think you will find 5 gallons of vinegar for $3.91. Still much cheaper.