RogueRose - 6-11-2015 at 03:47
I boiled down the filtered solution of Cal Nit and poured it into a 1/2" diam PVC mould (testing for timed release of fert) at 9" long while it was
hot liquid. It solidified and cooled then the very top of the pipe started absorbing H2O and got the watery look. About 8-12 hours later I finally
cut the length of the pipe to remove the cal nit plug. When I picked it up and started pressing with the razor, I noticed there was significant heat
coming off the top end of the material. I then noticed that the top was now dry, the moisture/watery look had disappeared and there was now a
division 1/2 way down the pipe - the top/hot part being more white and the bottom/room temp part was a darker cream color.
Anyway by the time I got the fert plug out it had all turned bright white and was warm.
What's the deal with this?
Ozone - 6-11-2015 at 20:03
Heat of crystallization, perhaps?
See "specific examples" where, "When the temperature of 17° C in the phosphonitrate solution was attained, a temperature jump to 24.5° occurred. The
phosphonitrate solution was cooled in continuation from 24.5° to 17° C at the same constant rate of cooling of 12° C/hour. During the temperature
jump and when the temperature of the pulp had again reached 17° C, a more rapid crystallization of the calcium nitrate took place."
http://www.google.com/patents/US4008309
For more on this, see "hot ice" (sodium acetate) which is the most common demo for this phenomenon.
https://www.youtube.com/watch?v=Yxk3OZWq9Ls
O3
[Edited on 7-11-2015 by Ozone]