Re: KRS - artificial weathering

From: Eric Stevens (eric.stevens_at_sum.co.nz)
Date: 09/17/04 

Date: Fri, 17 Sep 2004 21:54:48 +1200

On Fri, 17 Sep 2004 06:11:45 GMT, "zolota" <zolota3@REMOVEshaw.ca>
wrote:

>
>"Martin Reboul" <martin.reboul@SPAMFUKvirgin.net> wrote in message
>news:Joo2d.361$YE3.166@newsfe6-win.ntli.net...
>>
>> "I E Johansson" <ingerxjohanssonx@telia.com> wrote in message
>> news:W4o2d.103488$dP1.373031@newsc.telia.net...
>>>
>>> "Eric Stevens" <eric.stevens@sum.co.nz> skrev i meddelandet
>>> news:envjk0tfv5c3s7c9j8rfidcvbsepgagkc3@4ax.com...
>>> > On 16 Sep 2004 13:02:13 -0700, trolleyfan@earthlink.net (David
>>> > Johnson) wrote:
>>> >
>>> > >Eric Stevens <eric.stevens@sum.co.nz> wrote in message
>>> news:<2qtik0pbvlk7du6s6c3f4ke6fjsh6q81bv@4ax.com>...
>>> > >> On Thu, 16 Sep 2004 04:45:43 GMT, "Martin Reboul"
>>> > >> <martin.reboul@SPAMFUKvirgin.net> wrote:
>>> > >>
>>> > >> >
>>> > >> >"Daryl Krupa" <icycalmca@yahoo.com> wrote in message
>>> > >> >news:c70365ef.0409151557.51d3e94b@posting.google.com...
>>> > >> >> "zolota" <zolota3@REMOVEshaw.ca> wrote in message
>>> > >> news:<7fU1d.418855$M95.214117@pd7tw1no>...
>>> > >> >>
>>> > >> >> <snip genuine scholarly discourse, for a welcome change>
>>> > >> >>
>>> > >> >> Z:
>>> > >> >> Finally, some meat to chew on.
>>> > >> >> Thank you very much for elevating the standard of discussion;
>>> > >> >> very useful and interesting you have been, with this artificial
>>> > >> >> weathering material.
>>> > >> >>
>>> > >> >> > Does anyone here see an error in my thinking, or
>>> > >> >> > a way that such artificial aging could be detected?
>>> > >> >>
>>> > >> >> Not yet, but I'm trying to play Devil's Advocate and wear away
>>> > >> >> at it until a few pieces fall away.
>>> > >> >> But here's a poser:
>>> > >> >> is there some commonly-available sticky substance that is immune
>>> > >> >> to the effects of sulfuric acid, that might have been used to
>>> > >> >> mask the calcite and so protect it from degradation?
>>> > >> >
>>> > >> >Bitumen, but that would be hard to remove. Good old butter or lard
>>> would do the
>>> > >> >job quite well ...
>>> > >>
>>> > >> Nope. They would be hydrolysed by the acid.
>>> > >>
>>> > >> > ... and be easily removed with soap and a good scrub. That's what
>>> > >> >I'd go for.
>>> > >>
>>> > >> ... and you would fail.
>>> > >> >
>>> > >> >I doubt if they were that sophisticated however. Zolota's
>>> > >> >'weathering
>>> plan'
>>> > >> >sounds like the sort of thing that might well have been done.
>>> Basically, just an
>>> > >> >acceleration of the natural weathering processes using empirical
>>> > >> >and
>>> > >> >indetectable methods - all available in the C19 ....
>>> > >>
>>> > >> What are these indetectable methods?
>>> > >>
>>> > >> > .... without needing a laboratory.
>>> > >> >The use of salt and ice (to lower the temperature to almost -32C or
>>> zero F) is
>>> > >> >also hardly rocket science, and would have been well known back
>>> > >> >then.
>>> > >>
>>> > >> Its also a good antifreeze. Was that quite your intention?
>>> > >
>>> > >I see someone's never made ice cream...
>>> >
>>> > Salt and ice makes a freezing mixture with a lower freezing point. Get
>>> > the three together and you get a lower temperature mix. But to do that
>>> > you have to have liquid present. What Martin is looking for is solid
>>> > ice, not a sluch of water and ice. Adding salt will not help him
>>> > unless he does it in a separate bath which is somehow going to freeze
>>> > the KRS by conduction. Its a pity they didn't have plastic bags in the
>>> > 19th century. :-)
>>>
>>> Since I was one had the responsibility delivering salt to put on
>>> ice-roads
>>> here in Western Sweden 1976-79 I can confirm that between -6 degrees
>>> Celsius
>>> and +5 degrees Celsius(when supercold rain falls on ice-roads) the result
>>> when salt is spread on ice-surface will be melting water. As Eric
>>> indicated
>>> the air around helps the salt melting the ice and there will be no
>>> reaction
>>> alike David's imaginary weathering scenario. So I agree with Eric: What a
>>> pity they didn't have plastic bags in 19th century :-)
>>
>> And they put you in charge of delivering road salt - in Sweden!?
>> No wonder Volvo's are built like tanks!
>>
>> It's nothing to do with the air, it's simply that salt water freezes at a
>> lower
>> temperature than fresh.
>> Cheers
>> Martin
>
>A salt-ice-water mix will have a depressed freezing temperature but mixing
>the three can only be the sum of the sensible heat of the mix.

Sorry, you have forgotten both latent heat and heat of solution.

>If you
>started with 1 kg of ice at -9 degrees C, 500 g of ice water, and 100 grams
>of salt you will arrive at -6 C or so. If I was faking a surface I'd just
>drop the hot rock in ice water, it's the rate of cooling that does the most
>damage. A rock left outside overnight on a three dog night then hit with
>boiling water would also spall! If anything these methods may be too strong,
>but the serious forger would never have left something she was not satified
>with.
>
>It also seems to me that some stone masons must have traditionally had some
>some methods of artificially aging rocks. Say for example that a church
>wants to put an addition onto one side. The master with the reputation who
>could age the rocks to look like the originals would be in demand. It's
>probably a lost art today. Shall we all experiment with rocks using our
>freezers and kettles?

More likely confirm that my experience that stone masosn would rather
freshen up the entire church to look like new is the more common
practice.
>
>Despite what others say, a rock that had been in salt water would show no
>evidence of the salt later.

I never said that. What I was trying to pint out that Martin's attempt
to induce frost cracking by using salt to create a freezing mixture is
fraught with practical problems which he doesn't really understand.

Eric Stevens