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Speedball Low Fire Glazes Aren't Glossy... What Am I Doing Wrong?!


Dsuloff

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Someone with more experience please help! I was given a very old electric kiln, there is a peep hole but no kiln setter so I am doing my best to control the temperature with the low,med,high switches. I have been firing with a cone 06, my bisque fire came out perfect, but when I did the glaze fire (using speedball low fire glazes) they were basically clear. I thought maybe I just didn't put enough on so I refired everything with another layer of glaze and they came out even worse. They are no glossy, very transparent, and rough in texture. I saw somewhere on here that if the temperature wasn't hot enough the glaze can come out rough but my cone was just starting to slump when I turned the kiln off to slowly reduce heat. I don't think my gifts will be done in time for Christmas anymore but I'm afraid to completely ruin everything I make with this glazing issue! Hopefully someone can help!

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It does sound like they are indeed underfired.  What cone are you going to for glaze?  In my classroom, we use low fire.  I bisque to 04, but glaze to 05.  The only times I've had glazes turn out rough, are when not enough was applied, or they were designed to be rough/ textured.

 

So I would say, double check how much application is suggested and/ or what temp you are supposed to fire to.

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It does sound like they are indeed underfired.  What cone are you going to for glaze?  In my classroom, we use low fire.  I bisque to 04, but glaze to 05.  The only times I've had glazes turn out rough, are when not enough was applied, or they were designed to be rough/ textured.

 

So I would say, double check how much application is suggested and/ or what temp you are supposed to fire to.

I am firing the glaze to 06, I usually do the same in my classroom but we have a nicer kiln there! It sounds like they are under fired but I don't know how? There is no sign of the glaze running either as there is still a good half inch of bisque at the bottom.

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I will have to try firing them at a lower temperature! I tried to attach pictures but it says the file is too big. They are definitely low fire though. Do you think I can add another layer of glaze and refire them (for the 3rd time) again?

 

Also- since I only have low medium and high switches, how do you recommend firing? I've been turning it on low for about an hour, medium for an hour, and then high until I see my cone start to slump.

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HI, some points to consider…

-The bended cone you are seeing doesn’t necessarily mean the rest of the kiln reached the same temperature. I’m not sure what you mean when you say until I see my cone start to slump. You could check Orton’s website if you’d like to see a diagram of what a properly bended cone looks like. Maybe your kiln is not reaching cone 06.

- Is the firing time equal in both kilns?

- If the kiln you have at home is smaller or less insulated, you might need to fire a cone higher, do a soak at max temp or slow cool the kiln so the glaze gets to melt fully.

Some glazes start melting way before the cone drops, others melt fast near the end of the firing, and others bubble and need time to heal. I never fire glazes to cone 06 anymore. I fire with a 04 or 03 cone in the sitter and Speedball glazes rarely give me any troubles.

Speedball glazes I think use a different kind of gum and brush differently. I made test tiles big enough so I could brush the whole tile with one coat, ¾ with two coats, ½ with three coats, and ¼ with 4 coats to see the difference in terms of opacity and glossiness…  

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Thank you for all of the input! My kiln at home is about half the size as my kiln at work but it seems to be very well insulated, I can't even feel if it's on when I touch it. All I have on my kiln at home are two peep holes to look through at my cones. When I see the top of the kiln start to bend I leave my kiln on high for about an hour or when the rest of the cone starts to fall and then I turn my kiln off and leave the lid shut until it's room temperature. I am thinking I am just firing everything too hot based off of everything I've read... I usually only have my kiln on for a total of 4-5 hours so this surprises me.

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I would fire to cone 05 or 04. You need to fire until the tip of the cone touches the shelf. You must use large cones, not the small ones that go in the sitter. Fire 1/2 hour on low, 1/2 hour on medium, then high till done. Don't worry about how long the firing takes. Some smaller kiln fire quite fast. 

 

How many coats of glaze did you apply the first time?

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I would fire to cone 05 or 04. You need to fire until the tip of the cone touches the shelf. You must use large cones, not the small ones that go in the sitter. Fire 1/2 hour on low, 1/2 hour on medium, then high till done. Don't worry about how long the firing takes. Some smaller kiln fire quite fast.

 

How many coats of glaze did you apply the first time?

I will need to get the larger cones, I have been using the smaller ones. I applied 3 coats of glaze (worried that it would run) and it came out virtually clear, and the glaze is not transparent on the bottle. So I applied another coat thinking I didn't apply enough and they came out very rough but still pretty clear.

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