It gets rid of rust stains on tile and porcelain enamel very well, though. I fixed an apparently permanent stain on my bathtub that way, and it worked on JT's floor tiles too. The usual commercial brand round here is Naval Jelly.
Cheers
Phil Hobbs
--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics
160 North State Road #203
Briarcliff Manor NY 10510
hobbs at electrooptical dot net
http://electrooptical.net
HF is so corrosive it eats through glass - in labs, it is stored in stone bottles. Even when dilute, I'd be sceptical to the stopping power of ordinary gloves if I spilt it.
STONE!!?? The labs I worked in used plastic bottles.
Don't confuse an acid's "strength" with it's ability to dissolve a given material. Some materials are susceptible to one acid while resisting attack by another "stronger" acid. It often depends on how soluble the corrosion products are.
There is also the matter of the acid's concentration. The product described is only about 2% HF... and comes in a plastic bottle.
I can guarantee that anybody trying to remove rust with gels or liquids is going to get some of the stuff on themselves and all over the place by the time they're done. It would be prudend to check compatibility of protective gear and the substance being used. I recently leaned MEK soaks right through the rubber gloves I usually use.
The kicker with HF acid, strong or weak is it's absorbed though the skin and messes with your nerves. You don't want any direct exposure.
I just checked some pickling paste used for cleaning stainless steel welds it is is 2-6% HF and is says use face shield and acid resistant rubber gloves
and understand what is being explicitly stated, and what is being stated by inference.
A few examples:
"Hydrogen fluoride goes easily and quickly through the skin and into the tissues in the body. There it damages the cells and causes them to not work properly."
"Quickly take off clothing that may have hydrogen fluoride on it. Any clothing that has to be pulled over the head should be cut off the body."
"The damage may progress for several weeks, resulting in gradual and lingering narrowing of the esophagus"
Yes. Home Depot sells it, pretty concentrated too. It was for etching concrete IIRC, or some such. Liquid, not gel. It was a lot cheaper than the Naval Jelly, which they had too.
Oh, here it is:
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Phosphoric-acid containing products are magic as rust-converters. I used a bit on ye olde car as a stop-gap to temporarily keep an exposed rusty spot from propagating. It stopped the rust cold, and it's been years. I never did get around to "fixing it."
I second the magic of phosphoric acid rust converters. I have a number of old tools that started rusting badly when I moved to the rust belt of Ontario, Canada. I tried the various rust preventers but they were ineffective. I found the phosphoric acid products worked very well.
I like to study the chemistry to see how things work. In the case of phosphoric acid, there are two reactions, a fast and a slow. The fast reaction is
Fe2O3 + 2H3PO4 --> 2FePO4 + 3H2O
(Note there are three water molecules generated for every two molecules of rust that is converted.)
The resulting coating of FePO4 is hard, black and inert. I tried putting a couple of drops of bleach (sodium hypochlorite) on a tool that had been treated. Nothing happened. The black coating did not react. Hopefully this means rust spots on the car will be protected from the road salt in the winter.
The slow reaction takes longer:
2Fe + 2H3PO4 --> 2FePO4 + 3H2
Note this produces hydrogen gas instead of water. You can see the reaction by putting some steel screws in a bowl and addding H3PO4. This will produce bubbles of hydrogen and the screws will turn black. They won't rust.
There is Canadian product called Rust Check Rust Converter. It is sold in Candian Tire stores at $9.99 for 236mL. Here's the TinyUrl link:
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There is also a spray can version but I prefer to apply the liquid using a small brush so it goes where I want.
They also have a "Rust Remover" product that is in a similar can but it is completely different. It removes the rust without converting it and leaves no protection.
The MSDS for Rust Converter is unavailable at the moment, but it consists of 30% phosphoric acid, 30% tannic acid, and 30% isopropyl alcohol. The concentrations are not listed in the MSDS.
The tannic acid reaction also produces a hard, black, inert coating. Presumably this fills the gaps in coverage that may be produced in the phosphoric acid reaction.
The tannic acid chemistry is included here:
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The isopropyl alcohol does two things:
it penetrates narrow gaps and carries the phosphoric and tannic acid into tight joints.
it combines with the water produced in the first reaction and removes it from the metal when it evaporates.
As far as I can tell, the Rust Check product is the only one that contains tannic acid and isopropyl alcohol. I have not tried any other products to see what difference there may be, but I am quite happy with the performance of Rust Check. The only thing is the price. I tried buying phosphoric from a chemical supply house, but they wanted $50 per gallon and $50 for shipping. Now that I know there are cheaper sources, I will see if I can make my own. It will always be needed here in Canada.
Thanks for the tip for the cheap source of phosphoric acid.
Last weekend, I winterized my roof with its annual dose of wet patch roofing tar along the seams. I have 3 boxes with various grades of rubber, latex, nitrile gloves. I tried some gloves from each box, only to find that they tore apart when even slightly stretched. The oldest box may be 10 years old, so that would be expected, but one box was purchased new about a year ago. I still don't know what destroyed all the gloves, but I suspect it might have something to do with my kitchen chemistry experiments.
I didn't have time to go to the hardware store and buy some new gloves, so I used what I had, being careful not to stretch or rip them. That didn't work. The gloves came apart at the finger tips and wrist. I ended up with tar on the hands.
Even more topic drift and drivel:
A friend gave me his 4D Maglite to fix. The cap was stuck, which meant the battery inside had leaked and was probably stuck inside the aluminum tube. I confirmed this when I finally removed the cap using two pipe wrenches. It appeared that I might need to center drill the batteries and remove them with a big auger bit. I've done this before and it's rather messy. There must be a better way.
Next, I then decided to inspect my own flashlights. I have 6 Maglites scattered around the house, office, and car. Two of them (3D and 2D) had leaky batteries. I was able to extract the batteries from one, but the other is firmly corroded in place.
Next, I tried an experiment. Household ammonia cleaner reacts somewhat with the aluminum oxide(?) crud produced by the potassium hydroxide electrolyte in alkaline batteries. So, I poured some ammonia down the flashlight tube, which eventually leaked into the reflector and lamp area. After I cleaned up the mess, I discovered that the ammonia had completely etched away the metallic coating on the reflector. Oops.
At this point, my brain finally engaged and I realized I was using the wrong chemical. I switched to phosphoric acid (Naval Jelly Rust Dissolver), not caring much if it also attacked the aluminum. When the volcanic belching of corrosive muck finally subsided, and after a water rinse, the batteries from my 2D light came out fairly easily using a broken tape measure jammed between the battery and the aluminum tube. Unfortunately, it also undermined the black paint on the aluminum flashlight tube, which caused much of it to flake off. Lesson learned, dilute the phosphoric acid next time.
One more 4D flashlight to go. What (else) can go wrong?
--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
I've found that both still leak and Energizers are worse than most but if you're into warranties, that's the way to go. Don't know how many times they'll replace stuff for you though. I bought 100 no-name AAs from Home Depot about five years ago. They're just starting to leak. I've found that it's better to replace alkaline batteries no more than a year after they've been put into service and more immediately if they've been used for any time (say, 20-50% discharge).
The appliances are too expensive and warranties are too much hassle. ...which, of course, the bunny and copper are counting on.
I took Energizer up on their warranty once and they came through! They sent me a check for $100 based on my word alone. I think I had a problem with a Ray-o-vac battery once and they require substantiation of your claims, almost as much as an insurance company would... receipt of purchase, photos of damage...
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