Firing Laguna WC401 B-Mix Cone 5

[ShadePeg]

Hello. New user here. Not just on this forum, but to clay in general. 

I am trying to complete a project in which I want to create what's called a 'firing peg' used in the dental lab industry. It's a similar tool as kiln furniture for clay projects, but for small ceramic ovens (pictures included). I have managed to get my hands on some Laguna WC401 B-mix and have a few questions I hope that people here might help me with.

First, I'm trying to find some firing instructions. If someone has a link to something like that, Thank you. 

Second. I'm hoping to get some advice on whether this is in fact a good porcelain clay to use. These firing pegs need to be durable and repeatedly withstand heating up to as high as 1050 C (1922 F). 

Thank you so much. I appreciate any help I can get. 

[JohnnyK]

Welcome to the Forum, ShadePeg...The WC401 is NOT a porcelain clay although it is a smooth clay similar to porcelain. The firing pegs you show here look like they could be slip cast or press molded from something other than a smooth clay. The bubbles would tend to indicate slip cast... I would think that the B-Mix would stand up to repeated firings in your environment but I would take some time to run some tests before you make your final selection. Since you already have the clay on hand, I would run a number of pins you have fabricated through a series of test cycles along with the firings you do on a day to day basis to see if it works for you....

[ShadePeg]

7 hours ago, JohnnyK said:

Welcome to the Forum, ShadePeg...The WC401 is NOT a porcelain clay although it is a smooth clay similar to porcelain. The firing pegs you show here look like they could be slip cast or press molded from something other than a smooth clay. The bubbles would tend to indicate slip cast... I would think that the B-Mix would stand up to repeated firings in your environment but I would take some time to run some tests before you make your final selection. Since you already have the clay on hand, I would run a number of pins you have fabricated through a series of test cycles along with the firings you do on a day to day basis to see if it works for you....

Johnny, Thank you. I will look into all that you have said. I appreciate the clarification on WC401 not being  a porcelain. I have looked into slip cast, but thought it was not the right method, but I will take another close look. 

[neilestrick]

Does the peg need to be vitrified? If not, then just about any clay body should work if you just bisque fire it. I would think that you could just hand build these shapes if you just need a few, but if you're looking to make a whole bunch of them then consider making a press mold.

[ShadePeg]

19 minutes ago, neilestrick said:

Does the peg need to be vitrified? If not, then just about any clay body should work if you just bisque fire it. I would think that you could just hand build these shapes if you just need a few, but if you're looking to make a whole bunch of them then consider making a press mold.

No. Does not need to be vitrified. I've looked a little further into clays and I may try B Mix ^10 WC379, but it's nice to hear that any clay might do. 

Quick question about bisque firing. Let's say I'm firing this cone 10 clay. Should I fire it to the cone 10 temp, or should I back off a bit? I've heard that not firing clay to it's full temp will help it withstand the repeated firing during it's intended use. 

Thanks for your help. 

[Callie Beller Diesel]

Yes, if the peg does not need to be vitrified, you only have to bisque it.

But.

If the firing peg is only meant to be a support for another item, a different option might be to just make yourself some wadding. The simplest recipe is 50/50 by volume alumina hydrate and any dry clay, EPK being the most typical. Mix it with enough water to make it mouldable. Wadding is typically used in wood or soda firings to keep pots from sticking to the shelves, and it’s very refractory. Wadding isn’t fired before use on the pots, and is applied while the kiln is being loaded. They are usually considered a single use item because they’re formed to suit the specific pot. But if you need the same shape every time, you could make a press mould and keep them afterwards, because it does fire up very hard. 

 

[ShadePeg]

On 6/24/2021 at 10:30 AM, Callie Beller Diesel said:

Yes, if the peg does not need to be vitrified, you only have to bisque it.

But.

If the firing peg is only meant to be a support for another item, a different option might be to just make yourself some wadding. The simplest recipe is 50/50 by volume alumina hydrate and any dry clay, EPK being the most typical. Mix it with enough water to make it mouldable. Wadding is typically used in wood or soda firings to keep pots from sticking to the shelves, and it’s very refractory. Wadding isn’t fired before use on the pots, and is applied while the kiln is being loaded. They are usually considered a single use item because they’re formed to suit the specific pot. But if you need the same shape every time, you could make a press mould and keep them afterwards, because it does fire up very hard. 

 

Callie, If I wanted to make some of this wadding and form it in a mold to fire it up as a piece that could be used repeatedly, is there a temperature range I should consider? 

Thank you. 

[Callie Beller Diesel]

No, it’s pretty loosey goosey stuff. Usually it gets mixed up and used on the spot. It goes in the kiln wet, and with 50% alumina, it’s very refractory. 

[ShadePeg]

On 7/17/2021 at 11:15 AM, Callie Beller Diesel said:

No, it’s pretty loosey goosey stuff. Usually it gets mixed up and used on the spot. It goes in the kiln wet, and with 50% alumina, it’s very refractory. 

So, what I am thinking of mixing is 50% alumina with 50% Laguna Frost (WC896) and firing it at cone 10.  It's my understanding that porcelain would be a harder, more durable material than a clay.  Does that sound reasonable to you? 

Thank you. 

[neilestrick]

2 hours ago, ShadePeg said:

So, what I am thinking of mixing is 50% alumina with 50% Laguna Frost (WC896) and firing it at cone 10.  It's my understanding that porcelain would be a harder, more durable material than a clay.  Does that sound reasonable to you? 

Thank you. 

If you're going to mix in 50% alumina, there's no reason to use a clay as glassy and expensive as Frost. You'll negate any benefits of using Frost by adding alumina to it. Basically, it won't melt tight and glassy. Porcelain is clay, it's just a different blend than stoneware or earthenware. Due to it being so dense and glassy, it doesn't hold up well to repeated firings. The reason wadding works in repeated firings is because it is not at all dense. Just use EPK and alumina. Or use a cone 10 stoneware and only fire it to bisque temps.