Firing Kindergarten/First Grade Animal Sculptures

[kaelbu]

Hi all,

 I was thinking that I wanted to have my kindergarten and first grade students make animal sculptures for Mother's Day, but I have a few questions about firing.  I am basically a beginner and know almost nothing about firing ceramics - I have used our schools kiln before for flat objects like cookie cutter ornaments. I really want to do this project because I think it will be fun, cute, and way more creative for the kids, but I am worried about the firing process.

1) From what I have gathered it is best to hollow out clay if it is thicker than 1/2 in. Is this always true? I don't think that my students will be able to do this bit for themselves  and I'm not sure I want to take on hollowing out 24 clay animals by myself.

2) A lot of instructions I have read have suggested letting these things dry for 1 - 2 weeks. I have never done this with previous projects and have done a preheat in the kiln for 24 hours. Is this okay to do? 

Thanks for any help! 

[neilestrick]

Yes, everything should be under 1/2" thick. Let things dry a few days, then do a 5 hour preheat and you should be fine. Fire slow to be safe.

[Benzine]

A couple suggestions:

 

As you mentioned, you don't want to have to hollow out the sculptures yourself, and no one blames you.  So use a construction method, that would give you a consistent thickness, so you don't have to worry about it.  I would suggest Pinch-Forming, or formed Slabs.

My colleague, at the Elementary Buildings, has his students create Pinch Bowls, which once formed to a good thickness, they reform to turn them into "Monsters" or fish, where the opening of the bowl, becomes the mouth.  From there, they score and slip on eyes, fins, teeth, etc.  He does it with right around the same age range, you mentioned, and they turn out nicely. 

For even greater, and more exact control, over the thickness, slabs are your best bet.  Roll out slabs to the desired thickness, and then form them around an object, that has the general shape, you are looking for.  Different sized balloons work great for this.  You can use smaller balloons for the head of an animal, and a larger/ more inflated one, for the body. (Just don't forget to put vent holes in any completely enclosed space you create)  Alternately, I've had my own students wrap slabs around empty paint bottles, rolling pins, drape them over bowls, and even layered, crumpled newspaper.  A couple things with this approach:  One, thinner slabs work better, if using balloons, because they form around them easier.  I usually recommend to students, that they use a 1/4" thick slab.  Second, if using a "found" object, like a paint bottle or bowl, for support, cover it in newspaper or paper towels, so the clay doesn't stick to it.  You also do not want to mold it perfectly to the form of the object, as the clay will shrink around it, and it will then be very difficult to remove said item.  Along with this, if using balloons, it is a good idea to pop them, once the clay begins to set.  Otherwise, the clay will try and shrink, and the balloon eventually won't let it, so you'll get cracks in the clay.

 

Honestly, either method will work.  I lean more towards the pinching suggestion, as the students will better be able to do it themselves.  The slab method will nearly guarantee that you will have an even thickness, but rolling out slabs will difficult for students that young, and there are more steps involved.

 

Whatever you end up doing, just do as Neil mentioned, and fire slow, preferably with a Candling/ Water Smoking portion, before you begin the main portion of the firing. 

[Chilly]

+1 to everything above, and

When clay dries, it starts to shrink.  When it shrinks, the particles get closer together.  When particles get closer together, it becomes harder for the inside moisture to travel to the outside edges and evaporate away.

That is why we advise on maximum thickness, and to have a hole in enclosed forms.  It is to help the moisture escape, so the inner clay is able to dry out. 

No matter how long you let something dry, if the outer surface of the clay has closed up, the moisture cannot escape.  When that moisture is heated to boiling point 100C/212F the moisture turns to steam and expands 1,600 times.  Hence the explosions in the kiln.