blow out.

[jwhisperj]

Hello everyone,
As you know I am new to sculpting and just fired my first piece. My friend called and said that it blew out it's back and has a large crack down his face. I picked him up and she thought it was do to lack of kneading in the beginning. She does pottery and isn't really sure what happened, any ideas? Am I doing something wrong? Wrong clay?

Also, do I need to use a certain kind of wire for a armature ( not sure if that is what it's called ) or can I use what I have around the house?

Thank you all very much for your time.

Jessica

[Andrew Werby]

Did this clay piece have wire in it? If so, that would explain the "blow-out". Rigid armatures are commonly used in making statues in oil-based clay, which doesn't shrink and never gets fired. But they don't work in water-based (potter's) clay which will crack as it shrinks on the non-shrinking wire.

It's also possible for ceramic sculpture to do this if there is any residual moisture in it, or if there are any air pockets trapped inside the clay. In general, don't expect anything thicker than one inch to survive firing. If you make things that need to be thicker than that, get in there with a tool and hollow them out as much as possible, making sure that any hollow chamber is vented to the outside of the form.

There are some formulations of clay bodies that can go thicker, but they tend to contain coarse aggregate or some organic matter to lighten them (think bricks). You can mix your own clay body like that, but it takes some experimentation to get this to work right.

Andrew Werby
www.unitedartworks.com

[jwhisperj]

Thank you Andrew,
The figure did not have any wire in it, but it was very thick. I did not hollow him out so I bet you just hit the nail on the head there! I will keep that in mind and I think I will try oil based clay, I will have to do some research on it though. Thank you very much for your time.

By the way I love your third brooch.

Jessica

[iron ant]

Jessica,don't seat it as this does happen,as firing kilns and pouring molten metal is not a 100% exactly as it should go all the time.Andrew has good advice...IA

[jwhisperj]

Thank you IA, I am not to upset considering I am not a pro and this was by no means a master piece. I appreciate your reply's and am merely trying to learn from this experience. You guys have been so helpful already and I can't wait to get my hands dirty and share more! I am in the process of sticking my feelers out there to find what kind of clay works for me, so it will be a long procedure.

Thanks again for everyone's support!

[The Forge]

Try using balls of newspaper to make the inner armature for your clay pieces to be fired. It will burn-out in firing.:)

[jwhisperj]

Thanks Forge,

Silly question here but, if I were to use newspaper would I need a wire armature? If so do you have any recommendations for the type of clay that would be best suited for wire? Or do I just wrap clay around the newspaper? ( I know very dumb question..) It sounds like a great idea!
I am pretty computer illiterate and am having some trouble finding types of clay and the best uses for each kind.

What I am looking for is clay that can have wire and can be fired or self drying. That is if the self drying clay can still be worked for several days.

Thanks bunches you guys! Hope this makes sense I haven't absorbed my coffee yet. lol

[GlennT]

Andrew answered that earlier... you don't want to use wire because it does not shrink, in fact it should expand under heat, whereas the clay shrinks. Thus the different movement between the two when fired will cause cracks.

If you are using any kind of rigid armature, you should make it such that it can be removed before firing, i.e., the armature is there just long enough to support the work until the clay dries hard enough to be self-supporting.
Using newspaper has the advantage of offering support that does nopt need to be removed when firing.

I also noticed you mentioned possibly using oil-based clay. That is not a clay that you can fire. It is for modeling when the intention is to make a mold and then cast the work in another medium.

[rika]

Jessica, you mentioned air-dry clay, which is great for practice, but it's not nearly as durable as fired clay. You can use wire armature inside air-dry clay, but you have to cover the wire with something that allows room for the shrinking clay. I've been using aluminum foil loosely wrapped around the wire, and/or masking tape with good results. Cracks still can occur. Also, to prevent cracking, you have to follow the manufacturer's recommended thickness. Too thin or too thick causes cracks. You can work on air-dry clay for days, but you have to spray with water frequently and cover the piece in heavy plastic overnight.

I've seen someone use solid clay for smaller pieces (up to 12-18"). She pokes deep holes all over the piece with skewers, then smoothens the clay on top to cover up the holes. She dries each piece for a month, then fires them. But you have to use clay out of the bag, to make sure there are no air bubbles.

[grommet]

I've seen someone use solid clay for smaller pieces (up to 12-18"). She pokes deep holes all over the piece with skewers, then smoothens the clay on top to cover up the holes. She dries each piece for a month, then fires them. But you have to use clay out of the bag, to make sure there are no air bubbles.

Aren't you essentially creating air pockets unless you skewer in such a way that the air can get out?

[jwhisperj]

Thank you guys very much.
Glen I guess I just didn't really understand If Andrew meant wire in all clay or just the kind I used. Sorry for repeating the same question. I am beginning to like the idea of newspaper. It sounds pretty user friendly. Thanks for the clarification about the oil clay, not something I am ready to tackle just yet from the sounds of it.

Rika, Thank you for your info about self drying clay. It might be something worth keeping around the house for practice like you said. Tin foil around the wire makes alot of sense.

Well got to run I'll write more soon.

Thank you so much everyone, you are a real big help!
I appreciate you taking the time.

[The Forge]

Start the piece by using the 'coil method' of building and insert newspaper in the hollow as it gets higher. The most important aspect of using 'water based' clay is that the piece is thoroughly dry before firing. I go by the rule that if you touch the piece and it is cold, it is not ready. :)

[jwhisperj]

Sounds good Forge. I bet you're getting tired of the amateur q's but could you explain the coil method to me? I am not familiar with this. Do you mean twist the paper? Boy I feel like I am in over my head with you folks! You are all so nice though so that helps.

[jwhisperj]

Ok thanks everyone, I am going to give this a shot and I will post the results!

jessica

[The Forge]

I will not get tired of answering questions. That is how artists learn from the older ones. I even ask them myself. You probably know it by another name. Coil method is one of the most rudimentary ways of working with clay. You taking a small lump of clay and first forming it into a cylinder by squeezing it in your hand. Then rolling it on a table to create thin coils like 'snakes' of clay. As you roll them into a smaller diameter, they will elongate. Then you take these coils and lay them on top of each other in whatever shape that you need for the piece. As you pile them up, just smooth the inside and outside. This is used extensively in making pottery. As the 'tube' get higher, that is when you fill it with the newspaper for support. :)

[jwhisperj]

Forge,
I see. I am so new to this I had no idea about this method! Sheesh... I am thinking of trying a horse for my next piece, it is a toss up because I also want to do a standing manlike thing I drew a long time ago. A friend told me to stick with "Montana" thyme things but that doesn't really excite me, although I do enjoy horses. My main concern is the legs supporting the weight of the body while the clay is still wet. As I understand it this is when people use a temporary armature? I can fill it's body with newspaper to help keep the thickness and weight down, and go from there I guess.
There is alot more to this than I remembered. Thanks again, and if you are up to throwing out any more suggestions my way I am sure open!

[The Forge]

Make a centaur- half man half horse.

[GlennT]

Make a centaur- half man half horse.

Or a politician- half man half jackass, and usually hoarse.

[jwhisperj]

Good idea Forge.
GlenT, Thanks for the laugh, needed it on this rainy day.