Most frying pans are making secret plans to kill you in your sleep.

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ZonkeyBallsVicZincprimeiroTiffaneeBubTrish

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Brianl

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Secret? Hell mine came after me with a running blender. pretty scary....well until he ran out of Electrical cord and and the blender just shut off. Then there was this long awakward pause before the pan slinked back in the cabinet.

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Brianl Brianl

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Yeah, and let's hope the multidimensional living part of frying pans never finds out how to break into our dimensions. When that day comes, we will all be screwed.

+222 Reply

primeiro primeiro

They're plotting to kill us because so many people insist on using a metal spatula on non-stick ones... then wonder why the non-stick coating gets ruined.

+222 Reply

Thedudeyouhatetomeet Thedudeyouhatetomeet

In response to “They're plotting to kill us because so many...

I have two spatulas, both of them wooden.

Yet, I still can swear I can hear them planning on killing me.

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ZonkeyBalls ZonkeyBalls OP

Secret? Hell mine came after me with a running blender. pretty scary....well until he ran out of Electrical cord and and the blender just shut off. Then there was this long awakward pause before the pan slinked back in the cabinet.

+222 Reply

Brianl Brianl

If you could refrain from posting the intricacies of my secret world domination plans that would be great :)

+222 Reply

AliceD AliceD

Polytetrafluoroethylene

by That Guy

Arizona State University
April 27,1999

Introduction

Polytetrafluoroethylene (abbreviated PTFE, also known by the trademarks Teflon, Silverstone, T-Fal, Supra, Resistal, and others) was discovered accidentally in 1938 by Roy J. Plunkett of DuPont’s Jackson Laboratory in New Jersey. Since then, this seemingly innocuous material has quietly flooded the country. If the average person ever thinks about Teflon at all, it is to idly wonder, “How do they get it to stick to a fry pan?” But even a partial list of Teflon’s uses reveals that a vast amount of this material has been brought into the world. Common uses include:

Non-stick fry pans, cake pans, pizza pans, breadmaker pans
Deep fryers, waffle irons, griddles
Portable heaters
Irons with non-stick sole plates
Self cleaning ovens
Heat lamps
Curling irons
Hair dryers
Stovetop burners
Coffee makers
Medical implants
Prosthetic devices
High performance industrial filters
Scientific instruments
Electrical insulation

PTFE is widely used for its stability at high temperatures. Most polymers are unstable above the boiling point of water, but PTFE is stable at least to 260 C, and in some applications up to 400 C. It is used in electronic equipment for its combination of chemical resistance, heat resistance, and dielectric stability.

In all of this, there have been very few voices urging caution. A person who reads a lot might run across an occasional warning that Teflon releases poisonous gases when overheated. A few people might wonder about eating the flakes of Teflon that fall off their non-stick fry pans, but nobody ever seems to worry much about it.

The purpose of this paper is to investigate those questions and others, including:

Are there any hazards in the manufacture, use, or disposal of PTFE?
Is PTFE recyclable, and what are the proper disposal methods?
What are the breakdown mechanisms and resulting products of PTFE?
Are Teflon oil additives actually any good?
Is it true that PTFE kills parakeets?

Production

The manufacture of PTFE may begin in two ways. First, calcium fluoride is reacted with sulfuric acid to make hydrofluoric acid, and methane is chlorinated to trichloromethane. Alternately, the process can be done with hydrofluoric acid and trichloromethane already procured. Then they are reacted with a catalyst of antimony trifluoride to produce chlorodifluoromethane, which forms tetrafluoroethylene (TFE) with no catalyst at 590 to 900 C. The yield is typically about 95%, which is very important in the economics of the process. TFE tends to self polymerize (that is how PTFE was discovered), but careful control is required to get it to polymerize in the desired manner. Low molecular weight PTFE is not strong enough to be a useful material. Overall, the processes are complicated and very different from the methods used for other plastics, so PTFE is significantly more expensive.

PTFE is manufactured as a raw material in the forms of resin, powder, pellets, or aqueous dispersion, and then shipped to other manufacturers who actually make it into products. The forms are chemically identical but require completely different handling methods. Each form is processed in a different manner according to very specific instructions provided by the manufacturer. Getting the world’s non-stickiest stuff to stick to a fry pan is a very good trick, and DuPont won’t say how they do it, except that a “primer” is used. The dangers in these processes come not from the PTFE, but from the other materials involved. Powder methods usually involve combustible lubricants and extrusion at high temperatures and pressures, so fire is a danger, along with any other hazards from the lubricants. Water dispersions usually require baking to dryness, with possible release of TFE gas and the various surfactants used to stabilize the dispersion. In all cases the first line of defense is ventilation, but careful design is needed to be sure the ventilation actually removes noxious products. Merely blowing a lot of air around is not sufficient.

The only danger in producing raw PTFE, other than a fire in the factory or a slippery spill, is the TFE gas, which is also the primary product released during decomposition. The combination of TFE and tobacco presents a unique and insidious hazard. It is recommended to completely ban tobacco products from the work place. This is discussed further in the section on toxicity.

Fate

The fate of PTFE is rather simple: it is very likely going to be PTFE forever. It is the least reactive material known. It is not attacked by any known acid or base or any other kind of reagent, and does not dissolve in any known solvent, although if it has voids, the voids can absorb liquids or gases. There are just two things that will break down PTFE: temperatures in excess of 260 C, and ultraviolet light. Above 400 C, finely powdered PTFE can react violently with finely powdered metals, especially aluminum and magnesium. These conditions can be easily produced by grinding or sandblasting PTFE coated products, so some caution is warranted in machine shops and reclamation operations. Another hazard is pumping aluminum flake slurries through pumps or fittings lined with PTFE. This can cause unexpected and maybe violent failures in the equipment.

PTFE does not burn, but if heated, it breaks down into sub-micron particles and several toxic gases. These products are discussed in the section on toxicity. PTFE and PTFE coated products should never be mixed with domestic or industrial waste that may be incinerated. Preferred disposal methods are recycling and landfill. Incineration is permissible only in a plant equipped to remove hydrogen fluoride and other acidic combustion gases. Liquid dispersed resins are disposed by filtering out the solids and sending them to a landfill. The water always contains TFE gas (which is water soluble), but can be adequately processed by any waste water treatment facility that is prepared and permitted to do so.

Of special interest is the use of Teflon as an additive to motor oil. This seems like a good idea, but it doesn’t work as one might expect. DuPont has never endorsed the use of PTFE for this purpose, but apparently cannot stop dealers from using the Teflon trademark as long as the product actually contains DuPont Teflon. Recall that one method used in manufacture is extrusion of PTFE dispersed in a lubricant under certain pressures and temperatures. PTFE won’t stick to anything, but it will polymerize with itself and become lodged on rough surfaces or in tight passages. This is exactly what it does in a gasoline engine. Granules of PTFE form and grow, adhering by mechanically gripping roughened surfaces inside the engine, and sometimes plugging oil passageways and clogging rings. If this happens, PTFE can actually prevent normal lubrication. This is an application that should be avoided. If the used oil is improperly discarded there is little chance of the PTFE in it being broken down or reformed. If the oil is sent to a rerefiner as it should be, the PTFE must be filtered out and sent to a recycler.

Measurement

Because of the extreme nonreactive nature of PTFE, the only practical way to measure it is to physically separate it and weigh it When that is not possible and a precise measurement is needed, professional technicians must be hired at rates from $800 to $2000 per day, plus $25 to $150 per sample analyzed. In toxicity testing, only PTFE is used, so measurements are obtained by filtering the products out and weighing the filters. Several grades of filters are used together, since the effects depend more on the size of fume particles than on inherent toxicity. In other settings, a common approach is to analyze everything else in the system and assume that the mass not accounted for is PTFE.

Of greater concern is the presence of the monomer TFE. Small amounts of this gas are released at temperatures below the breakdown of the polymer, and increasing as the temperature rises toward 400 C. (In the case of non-stick fry pans, the amount of gas released by the PTFE at usual frying temperatures is comparable to the amount of gas released by the plastic handle.) Other gases are released at higher temperatures, and all these gases are easily measured with conventional instruments. In determining safety requirements for handling resins, such as in a factory, a measurement is not usually considered necessary. Instead, equipment is selected to cope with one milligram of TFE per kilogram of PTFE processed, since the solid product reliably contains very nearly that amount of the gas. It is suspected that this small amount of gas is responsible for the softening of solid PTFE at temperatures below 260 C. There is some evidence to support this, but it is not certain.

Toxicity

PTFE is not toxic at all, but when heated above 400 C it releases fumes that cause fever. This is called “polymer fume fever,” or PFF. In humans the symptoms are nearly identical to the symptoms of “welding fume fever,” and very similar to the effects from inhaling soot or other finely divided powders. The symptoms depend mainly on the particle size, which is about 0.05 micron. It is presumed that the particles are small enough to enter the alveolae and cause mechanical irritation there. Only one case of a person being killed by fluoropolymer (not necessarily PTFE) fumes has ever been reported, and that involved burning materials in a facility not equipped to handle the emissions.

Parakeets are known to be much more sensitive than humans to fume fever, and parakeet lovers are very worried about Teflon products in their homes. DuPont acknowledges that these things are true, but points out that frying with butter also releases similar amounts of toxic gases, and no bird has ever been known to die accidently from either butter or Teflon.

Researchers have also pointed out that the extreme toxicity sometimes observed in tests is only caused by pure fumes of PTFE produced by high temperatures without flaming. Mixing the polymer fumes with any other kind of fumes, such as wood smoke, greatly reduces the observed symptoms. The reasons for this are not clearly understood, but it has been confirmed. It is thought that the effect may be caused by the test apparatus, which recirculates fumes through the furnace, breaking any clumps back into fine particles.

TFE is also considered non-toxic, or at least non-carcinogenic, but causes the same PFF symptoms as PTFE particles. The TFE molecule is always smaller than the PTFE particles, so it is a more threatening nuisance. Symptoms also include choking, eye and nose irritation, mild central nervous system depression, and dry cough. Inhaling large amounts can cause cardiac arrest and death. A limit of 5 PPM in work areas has been recommended. TFE also has an annoying tendency to be absorbed by tobacco. Each cigarette in an open pack, carried for a few hours in an area where the concentration of TFE is within recommended limits, can absorb enough TFE to cause polymer fume fever when it is smoked outside the building later. This is quite remarkable but very real. Tobacco products should not be brought into the building at all. Likewise, PTFE and other fluoropolymer products should be used with great caution where tobacco products are made.

Other gases released by heating PTFE include:
1.Carbonyl fluoride -- Symptoms may include skin irritation, eye corrosion, respiratory irritation, or difficulty in breathing, and these symptoms may be delayed several hours. Immediate medical attention and/or observation may be required.
2.Hydrogen fluoride: A highly corrosive acid that can be absorbed in toxic amounts through the skin. Symptoms may be delayed. Immediate medical attention is required.
3.Perfluoroisobutylene: Symptoms in animals include wheezing, sneezing, and abnormally deep or rapid breathing. High concentrations cause pulmonary edema and death. Little is known about human exposure.
4.Carbon monoxide: High concentrations and/or long exposures cause sleepiness and possible nosebleed, followed by death.

These gases are usually only produced at temperatures well above 400 C and in the presence of water vapor. Very small quantities of these gases have been detected in finished products, apparently caused by the forming process and trapped within the plastic for a time. This illustrates the important of exactly following the manufacturer’s processing instructions. Such residual contamination can accumulate in sealed packages and closed storage areas, so packages should be opened in a ventilated area and storage rooms should be ventilated before entering them.

It is worth emphasizing that all of the dangers associated with PTFE occur almost exclusively in manufacturing or recycling operations. The danger from a piece of Teflon in any normal setting, including fumes and flakes from an aging fry pan, is zero.

Treatment and Pollution Abatement

The recommended treatment for waste PTFE is either recycling or landfill. Discarded PTFE is not a pollutant, and it is only a hazard if it is burned. The most abundant combustion product is TFE gas, which is not toxic but causes a fever when inhaled. The extreme sensitivity of some birds to TFE has been noted. At higher temperatures, PTFE also yields hydrogen fluoride, carbonyl fluoride, and a small amount of perfluoroisobutylene. Any installation that would incinerate PTFE must be prepared to remove these components from the exhaust. Modifying non-stick cookware for use in other ways should only be attempted with great caution, since such items are almost always made of aluminum, and attempts to grind or otherwise machine the combination of aluminum and PTFE can cause a fire or explosion.

Conclusions

PTFE is the safest material ever made by man. The manufacturing process is somewhat hazardous, and burning the waste is definitely hazardous, but otherwise it is totally safe, even for the extreme sensitivities of budgies. The only application found that is unsafe is as an additive in motor oil, and even then it can injure only the motor.
References

1. “Guide To The Safe Handling of Fluoropolymer Resins” 3rd Edition, 1998
Fluoropolymers Division Of The Society Of The Plastics Industry, Inc.

2. “Polytetrafluoroethylene Decomposition Products” http://www.osha-slc.gov:80/Chem...CH_263700.html
Occupational Safety And Health Administration, US Department Of Labor

3. ”Beaks - Teflon Kills Birds” http://www.iserv.net/~beaks/teflon.htm
Reprinted from The Parrot Post (The Parrot Club Of Manitoba) Feb. 1994

4. “Oil And Teflon: Slick 50 And Other Teflon Additives” http://edge.edge.net/~deschamp/teflon.html
Mike Deschamps

5. “Frequently Asked Questions About DuPont Fluoropolymers” http://www.dupont.com/teflon/faq/index.html
DuPont Corp.

6. “Polytetrafluoroethylene” http://www.psrc.usm.edu/macrog/ptfe.html
University of Southern Mississippi

+222 Reply

that_guy that_guy

Not mine. I welded them to my stove...Wait, what if they can carry a stove?..Screw that, I'm moving.

+222 Reply

azlotto azlotto

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