Wikipedia:Reference desk/Archives/Science/2016 July 12

= July 12 =

Teflon coating
What's the best way to apply a Teflon coating to stainless steel? 2601:646:8E01:7E0B:F88D:DE34:7772:8E5B (talk) 00:50, 12 July 2016 (UTC)
 * A Google search of your question provides several sources, such as: --2606:A000:4C0C:E200:A073:98E5:BA6B:E905 (talk) 04:23, 12 July 2016 (UTC)
 * This is a good starting point, but not detailed enough -- I need a source which is so detailed that even a politician would be able to use it to apply a Teflon coating (although some politicians do not need to apply any coatings to themselves, being actually born with a Teflon coating over their skin) ;-) Specifically: (1) What is the best way to roughen the surface with commonly available workshop equipment (if this is even possible)?  (2) What type of primer is needed, and under what circumstances can it be omitted?  (3) What is the best way to apply the actual coating?  (4) How many layers are typically needed for a durable coating, and how thick will it be in total with that number of layers?  And last but not least, (5) How do you do all this to the inside surface of a 1 1/4-inch pipe? 2601:646:8E01:7E0B:F88D:DE34:7772:8E5B (talk) 06:00, 12 July 2016 (UTC)


 * The short answer is "take the thing to your local Teflon™ Coating Service".  Here's a link if you really want to DIY: Application Overview for Teflon™ Industrial Coatings that explains Substrate Preparation, Surface Roughening, etc.  There are also some YouTube videos (good luck). --2606:A000:4C0C:E200:A073:98E5:BA6B:E905 (talk) 06:47, 12 July 2016 (UTC)
 * That's the info I needed. Thanks! 2601:646:8E01:7E0B:F88D:DE34:7772:8E5B (talk) 07:13, 12 July 2016 (UTC)


 * Get someone else to do it. Mixing fluorine-based polymers and ovens is not something for those who aren't doing it all the time. Andy Dingley (talk) 10:49, 12 July 2016 (UTC)
 * Right, that's what I plan to do (the DIY option is only as a last resort) -- the fumes won't kill you, but they can make you wish you were dead. 2601:646:8E01:7E0B:F89A:AB91:81AF:D78C (talk) 00:14, 14 July 2016 (UTC)

This may not be strictly related to answering your question, but out of curiosity, mind telling us why you would want to put Teflon coating on the inner surface of a 1.25-inch pipe? (Novel way of making eggs I'm unfamiliar with?) --Trovatore (talk) 18:38, 13 July 2016 (UTC)
 * Our PTFE article suggests it's commonly used in "pipework for reactive and corrosive chemicals" although I'm guessing pretty much everyone uses commercial products like   and are probably significantly wider than 1.25 inch. But there must be some systems where the pipe is that small and I'm sure I'm not the only one hoping that the OP is asking due to specific personal interest in how these are made not because they plan to DIY, whatever the purpose of the pipe. Nil Einne (talk) 20:00, 13 July 2016 (UTC)
 * FYI, my application is a packed bed chemical reactor which requires a Teflon coating on the inside both for corrosion resistance and for ease of removing the solid product -- and its basic shape is that of a 1.25-inch pipe (the diameter being dictated by the upstream plumbing and by the need to have plug flow throughout), but with outside fittings which are not normally found on any commercially available pipe, hence the need to custom-build it. 2601:646:8E01:7E0B:F89A:AB91:81AF:D78C (talk) 00:26, 14 July 2016 (UTC)

Van Allen Belts
I am thinking of making a spacecraft to fly outward and back through both Van Allen belts that surround the Earth. What sort, and thickness, of radiation shielding will I need to survive the round trip assuming I travel as fast as current space technology will allow? --86.187.170.21 (talk) 22:54, 12 July 2016 (UTC)
 * Van Allen radiation belt gives some values for radiation and shielding. The radiation received by the astronauts has been measured between 0.16 and 1.14 rads (1.6 and 11.4 mGy), much less than the standard of 5 rem (50 mSv) per year set by the United States Atomic Energy Commission for people who work with radioactivity. For comparison, a full-body dose of 5 Sv is deadly. AllBestFaith (talk) 23:18, 12 July 2016 (UTC)
 * Note also that this is not medical advice. Paraphrasing XKCD, if you are basing space travel safety procedures on a post on the internet and things go wrong, you have none to blame but yourself. Tigraan Click here to contact me 11:27, 13 July 2016 (UTC)
 * Right! It is also very important to have your insurance policies in order. YohanN7 (talk) 11:36, 13 July 2016 (UTC)


 * Is this a manned or unmanned spacecraft? Either way, a fast transit shouldn't pose to many problems. 131.251.254.154 (talk) 07:33, 13 July 2016 (UTC)


 * A Magnetic shield I think would be better. Also, consider sending just a robot to do the science. If you go yourself  and get a bad attack of the munchies along the way– the nearest pizza parlour will be a long, long, long way away. Yet, if you insist on traveling yourself, note this down in your Filofax: Both  Milliways and The Big Bang Burger Bar I think still do a home delivery service covering the Earth/Mars obits but their charges  I warn are bound to be astronomical, even to places like London in the UK. Let the magnetic force be with you – bon voyage .   The OP only mentions Van Allen's  belts but not his braces. Being elasticized, fly into one of those and you'll get catapulted back to where one started from. --Aspro (talk) 12:51, 13 July 2016 (UTC)

So how long can men be exposed to Van Allen radiation and still survive?--86.187.173.138 (talk) 20:54, 13 July 2016 (UTC)
 * The OP's question leaves no doubt that they are thinking of travelling in person. Quantitive LD50 values for human exposure to radiation might have been collected from the results of human sterilisation experiments with X-rays (see X-rays) and gamma rays (see Gamma radiation) but such experiments are no longer permitted. AllBestFaith (talk) 22:43, 13 July 2016 (UTC)