Firing Porcelite lattice object problem
July 27, 2016 at 12:11 am #823
Hi, I did my first firing on my lattice-like model following the instructions of “Fast Bisque for open lattice type objects, Cone 3” and things didn’t go as I would expect….
This is the link of some photos of the result,
would you take a look at them and identify what went wrong?
The fact that it broke is my fault, since the clay cylinder used as a container for the alumina hydrate and model got stack in the kiln, due to glass residues of previous kilned objects.July 27, 2016 at 9:42 am #824
I am just trying to make sure I understand what happened. Was there alumina hydrate in the cup when fired? How was the alumina hydrate used? Slowing down the firing is going to help your solid wall. The fast firing schedule is only for objects that only have a lattice structure. Since there is a solid wall on the inside a slower firing schedule is recommended. The object looks like it was restricted while it shrank. Something was not letting it shrink. That is why there are so many lines on it. Also the resin might need to be filtered through a kitchen strainer to throughly mix it if it has been sitting for a while.July 27, 2016 at 1:43 pm #828
The object is a cup with a lattice external decoration attached to the main solid body near the lip of the cup.
“Was there alumina hydrate in the cup when fired?”
Yes I filled the cup with alumina, sprinkled the bottom of the clay cylinder, turned the cup upside-down inside the clay cylinder and filled the inner and outer parts of the decoration with it, so yes it probably didn’t have much space to shrink.
Of what I understand it would be better if I didn’t fill the inside of the cup with alumina ?
Sorry but I don’t understand how the filtering with the strainer will mix the resin…July 28, 2016 at 11:02 am #829
Filtering the resin with a strainer will help break up the clumps of ceramic if any have formed. If there is not enough ceramic in the resin then it will shrink and warp differently than if it is fully mixed. The amount of ceramic material is important for good quality prints.
The best way to fire a cup is upside down but use the support material that is made from the printer. I leave supports on the inside of the cup and it still attached to the base. You can also use traditional wet clay porcalain to help support the object. Aluminum hydrate should only be used as support material on the outside of the cup. Not on the inside. The our side support can act like a nest around the cup. You can fire this way as well. The cup should be fired right side up with the opening facing up. The aluminum hydrate should be on the outside with no powder on the inside.
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