while I was over at my parents place for a party I poured some pieces that were needed for the projects we wanted to do and also to show more of this fun hobby. the two molds I poured were an insert for a large violet pot. thankfully it wasn’t one that was cleaned yet or fired, so we are only out of about $0.30 worth of slip and this is a large insert too. and the other is another mug for a friend. the photo’s of the process continue on from the first post ceramic pics
after the item has drained and sat for an hour to firm up it is ready to have the mold separated, before you can remove the top on most molds the spout has to be removed this is so the finished piece doesn’t stretch, rip or get deformed as the cover is being removed due to this spout.
this is what the violet pot insert looks like after the top has been removed. the dome section is actually scrap. that is removed before it is removed from the mold base. right now the ceramic material is like modeling clay and is very easy to cut now.
using a cleaning tool I cut near the line trying not to get too close or go too deep I go around the part. I can stay further away from the line and neatness doesn’t matter here since I have to cut, sand & smooth all the way back to that line later when it dries
making sure not to pull the finished piece as you separate the scrap section an remove it you pull it out and throw it away or find a use for it. setting it in water and stirring can turn it back into slip as far as i know but there can be consistency issues and some parts may not dissolve back to slip so we don’t try to salvage it.
oops, I cut too deeply in some spots gouging the side. no problem since it is still soft, just dab your finger into some liquid slip and wipe it across the cut to fill it in. using liquid slip is also used to “glue” pieces that have been poured together to be one piece. the complexity or shape of a figure makes it impossible to me poured as one piece.. If i find a mould that illustrates this that i like I’ll demonstrate that at a later time.
ta da, all fixed. when the part has completely dried and is ready to be cleaned the grooves left from my finger can be lightly sanded smooth.
here is the new mug I was pouring for a friend still in one side of the mold.
on the left is a mug after 3 days of drying. on the right is a mug after it has been cleaned up and is now ready to be fired for the next step of the process. tools like and xacto knife, a scotch brite pad and a wet sponge are all that are needed for simple cleaning, but to make the base and the top lip flat and level I attached sanding screen to a board and slid the base across until it was all uniformly flat and I did the same to the top for the same reason. sanding screen is used in drywalling for the same used. after it is sanded and trimmed to shape it is wiped with a damp sponge to smooth the edges a little more and to get all the dust off of the piece so it fires smooth.
the kiln itself is constructed of some kind of bricks the keep the heat inside the kiln. there are heating coils embedded into the walls to protect the elements and to optimize the space inside the kiln. My parents prefer to run the kiln in the evening. after it is loaded they start it on low to bring it slowly up to temp. every hour the come down to trigger then next switch to increase the temperature for all four switches. after that they leave it till morning. inside the kiln there is a switch that holds special wedges called ” pyrometric cones” the are designed to become soft and bend at certain temperatures and let the switch trigger to turn off the kiln at the desired temperature. for firing green-ware to become “bisque” ( once fired ceramic) takes a #4 cone. this reaches a temperature of 2124°F. usually this will take 2 hours to reach after the last switch was hit. after that they wait till morning for everything to cool off slowly. if the lid was to be opened the change in temperature would shatter the pottery on the top shelves.
all of these pieces except the large violet pot on the left were fired in one load. the inserts are fired inside the bases to make sure they still fit as they fire.
this is the violet pot base I posted about earlier. the pink glaze inside will turn clear when it is fired and the exterior will turn a darker green. the glazes will also develop a smooth glass surface like on store bought ceramics. this also seals the ceramic material so it doesn’t absorb or retain moisture. the interior glaze is actually a food save glaze that can be used on food and drink surfaces such as the mugs I am making.
if you noticed the lip and just a little past that is all that is glazed on this. this is how the violet pot works if you don’t have one. the porous material slowly pulls the water through bare ceramic to keep the plant soil moist but not flooded.
