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I searched for this topic in this forum and could not find the information I needed so I apologize ahead of time if this is something that has been discussed here. I purchased some porcelain kitchenware on sale for the purpose of using it for slumping. The surfaces are shiny and it seems impossible to put a smooth coat of kiln wash on the surface. I work with Youghegheny COE 82 glass and have a Paragon Fusion 16 kiln with heating elements in the lid. I am concerned about the glass sticking to the porcelain and the uneveness of the kiln wash. I would appreciate any advice...

I have several pieces of kitchenware that I use as molds. If the glaze is shiny, I attack it with my hand sander or hardware cloth, anything to give it some 'tooth.' I then spray them with kiln wash. I've used a set of Chantal dishes for several years.

If you have access to a sandblaster, blast the glaze off, then kiln wash. If you can't sandblast, rough it up by hand as much as possible before kilnwashing.

If the shape permits, you can cover with thinfire shelf paper.

The porcelain coating is actually made with crushed glass that flows at 1400ºF. So, essentially it is a glass on steel mold. You will be better off with a stainless steel mold. Regular kitchenware stainless is good.

This thread seems to be answering the question I just asked in the 'Pot Melt Primer' thread. I asked about porcelain tiles but the information seems relevant. Thank you, Valerie, Bert, Brad and the original poster. Jen

Perhaps I misunderstood what you meant; I use glazed ceramic ware from the kitchen store, or thrift stores, etc. There is no metal. I'm thinking that Bert and I are talking about two different types of ware.

Valerie Adams wrote:Perhaps I misunderstood what you meant; I use glazed ceramic ware from the kitchen store, or thrift stores, etc. There is no metal. I'm thinking that Bert and I are talking about two different types of ware.

The Chantal ware I am familiar with is enamel on steel. It is often called porcelain enamel. The enamel for this is simply glass frit applied to the steel and fired to 1400ºF. I once took a class in enameling on steel, using Thompson Enamels. Typically, both sides of the steel are coated with the glass, to balance out the COE's. Glazed ceramics are essentially glass on ceramic.

A fast down and dirty method on glazed ceramic surfaces is to coat with spray adhesive, then dust on a layer of dry kiln wash. I use my small glass enamel/powder dispenser to make a smooth layer. The glue burns out but the powder stays in place. Have gotten multiple uses if the mold surface is not disturbed. Can't recommend it for a deep slump or one with detail, as the glass may drag the dry powder as it moves. Great for a shallow shape if you are in a hurry.

huh. spray glue. i like that. thanks. rosanna

Thank you all for your suggestions. I really appreciate it. Looks like I will have to do some serious sanding. I bought these items at a cooking store and believe they are 100% porcelain.

Boyce Lundstrom sells a product called Universal Mold Coat that he says can be used on stainless steel moulds as well as glazed ceramic ones. It comes as a powder and is mixed with latex paint and water. See: <http://www.boycelundstrom.com/products/ ... d-coat-8oz>

I haven't used it yet so I can't say whether or not it works.
Jennifer

Faye Malench wrote:A fast down and dirty method on glazed ceramic surfaces is to coat with spray adhesive, then dust on a layer of dry kiln wash. I use my small glass enamel/powder dispenser to make a smooth layer. The glue burns out but the powder stays in place. Have gotten multiple uses if the mold surface is not disturbed. Can't recommend it for a deep slump or one with detail, as the glass may drag the dry powder as it moves. Great for a shallow shape if you are in a hurry.

Faye, that sounds too easy....what is the max. temp. that method will handle, please?

I too, have some porcelain dishes I bought hoping to remove the glaze and use as moulds. I've put off sand-blasting or sanding them. Thanks, Jen

The simple need is to keep glass from touching glass. I have fired 2 sheets of glass on top of a sand mold with a layer of alumina hydrate sifted between the sheets of glass. This worked fine. So, whatever you can do to prevent glass from touching glass should allow for the shapes to conform and the glass on top to anneal as envisioned. If you fail to keep the glasses apart, the top glass will stick and then it will not anneal properly.

Jen, I have only ever used spray and dry powder at my regular slump temps, which would be up to 1225. I would not attempt it at fusing temps.

Jennifer, the Universal stuff does work but use with caution. I have had several pieces with the solution embedded in the contact surface of the glass. Instructions say that will wash away but it does not always. I wrote to BL about the temperature parameters thinking I had fired too hot or long; received no response. I find it works best if you paint both the ceramic mold AND the back of the glass blank prior to firing. Not bashing the product - it works - just not consistently.
The nice part is - wash the stuff off the ceramic mold and take it back for intended kitchen usage. F

Thanks, Faye. That's high enough for me. Jen

Jennifer, the Universal stuff does work but use with caution. I have had several pieces with the solution embedded in the contact surface of the glass. Instructions say that will wash away but it does not always. I wrote to BL about the temperature parameters thinking I had fired too hot or long; received no response. I find it works best if you paint both the ceramic mold AND the back of the glass blank prior to firing. Not bashing the product - it works - just not consistently.
The nice part is - wash the stuff off the ceramic mold and take it back for intended kitchen usage. F[/quote]

Faye,
Thanks for the "heads-up". May I ask - how does painting the back of the glass blank, as well as the mould, prevent the solution from embedding itself in the glass as you mentioned?
Jennifer

Am I correct to assume you must drill holes for air to escape during slumping?

Vonon wrote:Am I correct to assume you must drill holes for air to escape during slumping?

I have several "dishes" I use for slumping that don't have holes. If they're shallow enough, you don't need them.

Jennifer, total guesswork on my part. For a normal smooth contour, as in a shallow bowl or plate, you could use one coat on the mold. It's thick stuff after it's mixed with latex paint and holds up OK. I was trying to use it with some tricky shapes like a tiny egg-crate, and a deep spiral ceramic piece. By coating both the glass and the mold, when the glass moves it is less likely to disrupt the coating on the mold.

Supposedly, you can slump multiple pieces at the same time by coating between them and then slump the stack. I tried that on a small scale... needed to curve a batch of 3 inch strips so painted them up; squeezed them togther and slumped. They all stuck together.

I have probably stretched the product outside the intended guidelines. Yet my thinking can be pretty concrete at times - it's says "Universal", so we should be able to do that, right?

PS: I don't drill holes in the ceramic stuff. So far, so good.