Toulouse Sand Field Notes
RATIONALE:
We are using the opportunity provided by the Frick project to test
I heated the already-ground Pech David sand for approximately 30 minutes in a pie pan on the highest setting of the hot plate. This was done in a fume hood. The sand produced small amount of smoke (steam?) when I would stir it after about 10 minutes of heating. Temperatures throughout the mixture varied, but sand close to the hot surface of the pan registered over 500 F on the IR thermometer. The sand that was hottest changed color slightly and appeared a bit more brown than other sand.
It occurs to me now that the heating process will take a very long time (hours) with lots of stirring, even at this high temperature. PHS: why?
I have to leave the lab soon, so I turned the hotplate off and waited for it to cool. The hotplate was on for approximately 30 minutes.
I suggest heating on Monday from the beginning of class and then throughout the day.
I heated the sand again beginning at 12:30pm. The sand turned much darker brown. I turned the hotplate off just before 4 pm.
Plan:
[THU] The recipe called for dry pounced sand ground very small for the face of the medal to capture detail. Elsewhere he describes using vine charcoal for a separator. On top, he describes using wet sand with the binder magistra. He suggests elsewhere to mold one day, bake/allow to dry the next day, and cast a different day. (Fol 87 b. “Mold in one day, bake slowly the next day, then cast the other”—this is the process for mold making when your sands are prepared)
[THU] The medal was laid out in one half of the casting flask resting on a large baking sheet with a large trapezoidal piece of beeswax adjacent to the top side to serve as the eventual gate. Two +/- 1” lengths of halved chopsticks were placed at the 5 and 7 o’clock positions, branching off of the bottom of the medal to give additional metal and gasses a place to go during casting and to (perhaps?) help with removing the medal from the newly-formed mold.
[THU] Finely-ground charcoal was placed in cheesecloth in order to pounce a light layer of charcoal dust across the surface of the medal and the casting infrastructure. Extremely finely-ground peche david sand was pounced over the charcoal layer, again with cheesecloth, in greater quantity, until details of the objects beneath were no longer discernible.
[THU] The recently baked Peche David sand was ground in a Krupps electric coffee grinder to ensure a uniform fineness. It was hand blended in a glass bowl with splashes of apple cider vinegar (with mother) until it achieved a consistency whereby the wet sand could be squeezed into handful-sized clumps (according to the “squeeze test”); those clumps could still be made to crumble by pinching between the fingers and thumb.
[THU] The wet sand mixture was used to fill the remainder of the first half of the casting flask. It was pressed in and compacted with the flat surface of a rubber mallet and eventually levelled with the long handle of a wooden spoon. Excess wet sand was swept away and removed from the baking sheet (returning it to the bowl of wet sand). The flask and baking sheet were held together and turned 180 degrees. The baking sheet was put back beneath the now inverted first-half of the flask.
[JAK] I repeated the process with Saint-Michel sand and vinegar, noting that this sand did indeed have larger clumps and what appeared to be a higher clay content. Certain clumps had a whitish clay that felt similar to bentonite clay (which is often used in green sand). The sand appeared dry, so we skipped the step of drying it in an oven. When I added the vinegar to the sand, I noted that it frothed, as is common in an acid-base reaction.
I made a cast of the small armed services medal using the small, mason-jar-lid casting flask. The sand took the impression rather well. I dried the sand in the mold and cast in a 3:1 alloy of tin:lead. I did not clamp the mold or use any weight on top and the medal cast poorly. Next time I suggest using some kind of clamp and pouring with the flask at an angle.
Pictures Are Here:
https://www.flickr.com/photos/128418753@N06/albums/72157676420909430
https://www.flickr.com/photos/128418753@N06/albums/72157675246512246