# Urine and ancient manufacturing **URL:** \ **Category:** Factual Questions\ **Created:** [October 2, 2015, 5:10pm UTC](https://boards.straightdope.com/t/urine-and-ancient-manufacturing/733277 "2015-10-02T17:10:10Z")\ **Posts on this page:** 15\ **Page:** 2
**Author:** ![Bones\_Daley](https://avatars.discourse-cdn.com/v4/letter/b/bc8723/32.png) [@Bones\_Daley](https://boards.straightdope.com/u/Bones_Daley)\ **Post date:** [October 3, 2015, 8:25pm UTC](https://boards.straightdope.com/t/urine-and-ancient-manufacturing/733277/21 "2015-10-03T20:25:30Z")
> [@bob\_2](#): > > New management, in an effort to reduce inventory, decreed that this lead time be reduced and the castings stored inside so they wouldn’t go rusty. The result was numerous warranty claims as the machined bases warped and threw the driveshaft out of line. Typical example of what happens when accountants exert undue influence in management. It was the storing outside that gave the castings their stability … they would have been exposed to summer heat, and also to freezing temperatures … this thermal cycling was (and is) crucial to achieving stability in iron castings. ---
**Author:** ![Isilder](https://avatars.discourse-cdn.com/v4/letter/i/cc9497/32.png) [@Isilder](https://boards.straightdope.com/u/Isilder)\ **Post date:** [October 5, 2015, 12:36am UTC](https://boards.straightdope.com/t/urine-and-ancient-manufacturing/733277/22 "2015-10-05T00:36:42Z")
> [@Bones\_Daley](#): > > I always understood that time alone was the sole factor in stabilising iron castings. No, time itself does nothing. Its the cycling of warm to cold, and then the number of. The idea is that cast iron is brittle and prone to cracking, and the cycling might prevent significant cracks forming when its exposed to in-use heat cycles. On a normal day,there’s only the one cycle as the sun heats up the day and then then night cools things down. So its possible that the drain water was warm and cold, adding more cycles. On the other hand, the salts would cause corrosion ? Well cast iron is particularly slow to corrode… ---
**Author:** ![Surreal](https://avatars.discourse-cdn.com/v4/letter/s/eada6e/32.png) [@Surreal](https://boards.straightdope.com/u/Surreal)\ **Post date:** [October 5, 2015, 6:08am UTC](https://boards.straightdope.com/t/urine-and-ancient-manufacturing/733277/23 "2015-10-05T06:08:42Z")
> [@CalMeacham](#): > > If you plunge the steel into water, it forms a vapor layer that retards cooling, defeating your purpose. Plunging it into oil is better – you don’t get that Leidenfrost effect. Not so. Normally water’s high thermal conductivity and high heat capacity more than compensate for its greater Leidenfrost effect, resulting in faster quenching than with oil quenching. In general, cooling rates for various quench media are as follows: water quench \> oil quench \> air quench \> furnace quench. ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [October 5, 2015, 11:01am UTC](https://boards.straightdope.com/t/urine-and-ancient-manufacturing/733277/24 "2015-10-05T11:01:44Z")
> [@Surreal](#): > > Not so. Normally water’s high thermal conductivity and high heat capacity more than compensate for its greater Leidenfrost effect, resulting in faster quenching than with oil quenching. > > In general, cooling rates for various quench media are as follows: water quench \> oil quench \> air quench \> furnace quench. Hmm. So you’re telling me my Materials Science professor got it wrong? ---
**Author:** ![Surreal](https://avatars.discourse-cdn.com/v4/letter/s/eada6e/32.png) [@Surreal](https://boards.straightdope.com/u/Surreal)\ **Post date:** [October 5, 2015, 2:00pm UTC](https://boards.straightdope.com/t/urine-and-ancient-manufacturing/733277/25 "2015-10-05T14:00:03Z")
> [@CalMeacham](#): > > Hmm. So you’re telling me my Materials Science professor got it wrong? Either that or you’re misremembering something from decades ago. ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [October 5, 2015, 2:27pm UTC](https://boards.straightdope.com/t/urine-and-ancient-manufacturing/733277/26 "2015-10-05T14:27:23Z")
The quenching thing is probably a lot more complex than just choosing between oil and water. There will be a big difference in the way you would quench a sword and a horse shoe. If uneven cooling causes the show to warp it can be readily heated and pounded back into shape. A sword may be ruined requiring much more rework if the quenching causes uneven cooling. Massive parts may have many more considerations including the hot and cold cycling. The part about pissing on castings does sound kind of hokey, but maybe it’s purpose is to rapidly promote corrosion on the surface of the casting which could provide some stress relief. Or maybe it’s started with a prank, telling someone they had to go take a leak on their casting every day so it wouldn’t get ruined. That one might have lost popularity after left-handed screwdrivers and sky hooks were invented. ---
**Author:** ![filmore](https://avatars.discourse-cdn.com/v4/letter/f/7993a0/32.png) [@filmore](https://boards.straightdope.com/u/filmore)\ **Post date:** [October 5, 2015, 2:37pm UTC](https://boards.straightdope.com/t/urine-and-ancient-manufacturing/733277/27 "2015-10-05T14:37:53Z")
When I was a kid, a friend of my parents was telling a story where he was in Mexico and a rock broke the oilpan on his motorcycle. He said the locals mixed clay and urine to patch the hole and when it dried, it was hard as steel. He said they jammed a screwdriver straight into the patch and it did nothing. As a kid I believed it, but now I’m wondering if that’s true. Is there anything special about mixing urine and clay? Or did they use urine because it was all they had and water would have worked just as well. ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [October 5, 2015, 3:28pm UTC](https://boards.straightdope.com/t/urine-and-ancient-manufacturing/733277/28 "2015-10-05T15:28:40Z")
I saw a documentary on Russian prisons that discussed their tattoos. They used electric razors to make a tattooing gun, and for ink they used a mixture of soot and urine. One prisoner pointed out that a lot of prisoners have diseases so you want to use your own urine. ---
**Author:** ![Surreal](https://avatars.discourse-cdn.com/v4/letter/s/eada6e/32.png) [@Surreal](https://boards.straightdope.com/u/Surreal)\ **Post date:** [October 5, 2015, 3:33pm UTC](https://boards.straightdope.com/t/urine-and-ancient-manufacturing/733277/29 "2015-10-05T15:33:36Z")
> [@CalMeacham](#): > > Hmm. So you’re telling me my Materials Science professor got it wrong? > **[Steel Castings Handbook, 6th Edition](https://books.google.com/books?id=QG3_QqmPZ_AC&pg=SA24-PA32&lpg=SA24-PA32&dq=%22severity%2Bof%2Bquench%22%2Bwater%2Boil&source=bl&ots=alHtIwzikV&sig=SmpbXk0tOwIL4Rywc796b5eCKxo&hl=en&sa=X&ved=0CCMQ6AEwAWoVChMI49a16NKryAIVStQeCh2xZQeG#v=onepage&q=%22severity%20of%20quench%22%20water%20oil&f=false)** > **[Handbook of Heat Treatment of Steels](https://books.google.com/books?id=yu2r5uqJBGIC&pg=PA31&dq=%22severity%2Bof%2Bquench%22&hl=en&sa=X&ved=0CDAQ6AEwAWoVChMI87LInNOryAIVgxUeCh2JzQKa#v=onepage&q=%22severity%20of%20quench%22&f=false)** > > A unique feature is the large number of data sheets provided giving the chemical composition, physical and mechanical properties and the general characteristics of steels and their corresponding international standard grades. Also, given are the heat... [http://www.google.com/imgres?imgurl=http://www.msm.cam.ac.uk/phase-trans/2000/practicals/AP3/Image5.gif&imgrefurl=http://www.msm.cam.ac.uk/phase-trans/2000/practicals/AP3/AP3.html&h=364&w=445&tbnid=aau-iyzhwsY4BM:&docid=G6cXqLBBiGY1KM&ei=aoUSVpiaMcTbe4XplcAH&tbm=isch&ved=0CEgQMyghMCFqFQoTCJj3o-LBq8gCFcTtHgodhXQFeA](http://www.google.com/imgres?imgurl=http://www.msm.cam.ac.uk/phase-trans/2000/practicals/AP3/Image5.gif&imgrefurl=http://www.msm.cam.ac.uk/phase-trans/2000/practicals/AP3/AP3.html&h=364&w=445&tbnid=aau-iyzhwsY4BM:&docid=G6cXqLBBiGY1KM&ei=aoUSVpiaMcTbe4XplcAH&tbm=isch&ved=0CEgQMyghMCFqFQoTCJj3o-LBq8gCFcTtHgodhXQFeA) [http://www.google.com/imgres?imgurl=http://www.navaching.com/forge/forge.gifs/paths.jpg&imgrefurl=http://www.navaching.com/forge/cooling.html&h=521&w=496&tbnid=2V\_Qm5u6zdFerM:&docid=pCEN0nf3xyUYIM&ei=gYMSVr3PKYPne4mig4AJ&tbm=isch&ved=0CB8QMygDMANqFQoTCP2Thvm\_q8gCFYPzHgodCdEAkA](http://www.google.com/imgres?imgurl=http://www.navaching.com/forge/forge.gifs/paths.jpg&imgrefurl=http://www.navaching.com/forge/cooling.html&h=521&w=496&tbnid=2V_Qm5u6zdFerM:&docid=pCEN0nf3xyUYIM&ei=gYMSVr3PKYPne4mig4AJ&tbm=isch&ved=0CB8QMygDMANqFQoTCP2Thvm_q8gCFYPzHgodCdEAkA) ---
**Author:** ![Yllaria](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/yllaria/32/3452_2.png) [@Yllaria](https://boards.straightdope.com/u/Yllaria)\ **Post date:** [October 6, 2015, 1:09am UTC](https://boards.straightdope.com/t/urine-and-ancient-manufacturing/733277/30 "2015-10-06T01:09:07Z")
> [@RadicalPi](#): > > To be fair, even today, there are people who deal with this. They’re at the other end of that “flush.” True, although it’s usually not quite so up front and personal. Well, not most days. ---
**Author:** ![even\_sven](https://avatars.discourse-cdn.com/v4/letter/e/dfb087/32.png) [@even\_sven](https://boards.straightdope.com/u/even_sven)\ **Post date:** [October 6, 2015, 1:43am UTC](https://boards.straightdope.com/t/urine-and-ancient-manufacturing/733277/31 "2015-10-06T01:43:45Z")
Imagine the only physical things that your community has access to are rocks, sticks, dirt, plants, water, whatever animals you can catch and the rare piece of expensive metal. This is it. It’s all you have to make shelter and the things for daily life from. That’s all the kids have to play with. When the teenagers hang out on the weekends, that’s what they have around them. It’s not going to be long before you guys understand the properties of all of those materials. Between experimentation and chance, you are going to know these things inside and out. There are only so many combinations you can come up with. For leather, there are a million ways to figure it out. The baby keeps peeing on the hide being used as a blanket. Someone tries to store urine in a skin bag while it’s too cold to go outside to pee. Someone notices that urine has a strong smell, and figures that like most things with a strong smell it probably has some interesting properties. The same with clothes. Clothing gets soaked with urine all the time, especially in the days before diapers. ---
**Author:** ![BrotherCadfael](https://avatars.discourse-cdn.com/v4/letter/b/977dab/32.png) [@BrotherCadfael](https://boards.straightdope.com/u/BrotherCadfael)\ **Post date:** [October 6, 2015, 4:06am UTC](https://boards.straightdope.com/t/urine-and-ancient-manufacturing/733277/32 "2015-10-06T04:06:54Z")
> [@MOIDALIZE](#): > > So it’s like the first person who ate shellfish? Someone was crazy enough to try, found out you could do it, and spread the word? ``` **“He was a bold man that first ate an oyster.”** ― [Jonathan Swift](http://www.goodreads.com/author/show/1831.Jonathan_Swift) ``` > [@RadicalPi](#): > > To be fair, even today, there are people who deal with this. They’re at the other end of that “flush.” “The plumbers’ union is demanding $50 an hour!” “That’s a lot of money for remembering that water flows downhill.” “It ain’t all water!” ---
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [October 6, 2015, 4:11am UTC](https://boards.straightdope.com/t/urine-and-ancient-manufacturing/733277/33 "2015-10-06T04:11:01Z")
> [@Smeghead](#): > > [It was used in the manufacture of tweed cloth for many years.](http://www.harristweed.org/blog/2013/02/dyeing/) Nice site. Thanks. So that’s where a “dyed in the wool Commie,” eg, comes from… ---
**Author:** ![MrQwertyasd](https://avatars.discourse-cdn.com/v4/letter/m/9d8465/32.png) [@MrQwertyasd](https://boards.straightdope.com/u/MrQwertyasd)\ **Post date:** [October 6, 2015, 5:24am UTC](https://boards.straightdope.com/t/urine-and-ancient-manufacturing/733277/34 "2015-10-06T05:24:16Z")
> [@CalMeacham](#): > > The “quenching” of steel to create a tempered item has a lot of mystique and downright error in it. If you plunge the steel into water, it forms a vapor layer that retards cooling, defeating your purpose. Plunging it into oil is better – you don’t get that Leidenfrost effect. There are grisly stories about plunging a red-hot sword into human bodies – except that, being mostly water, you’d think this would be no more effective. If you dunk it in dragon’s blood you get a +3 magic sword. ---
**Author:** ![md2000](https://avatars.discourse-cdn.com/v4/letter/m/73ab20/32.png) [@md2000](https://boards.straightdope.com/u/md2000)\ **Post date:** [October 6, 2015, 5:29am UTC](https://boards.straightdope.com/t/urine-and-ancient-manufacturing/733277/35 "2015-10-06T05:29:19Z")
> [@TriPolar](#): > > … > > The part about pissing on castings does sound kind of hokey, but maybe it’s purpose is to rapidly promote corrosion on the surface of the casting which could provide some stress relief. Or maybe it’s started with a prank, telling someone they had to go take a leak on their casting every day so it wouldn’t get ruined. That one might have lost popularity after left-handed screwdrivers and sky hooks were invented. I imagined it more like… “Smitkins! What the hell are you doing out here pissing on company property?!” “Well, uh, you see boss, uh… it hardens the castings faster. Yeah, that’s it - it hardens the casting faster, I’m trying to improve the quality of our product!” “oh, good idea. I’ll order everyone to pee out here on the castings from now on.” [Previous page](https://boards.straightdope.com/t/urine-and-ancient-manufacturing/733277.md?page=1)