59 replies to this topic

[Pam S]

Has anyone tried this glaze? I just took Ancient Jasper out of the kiln. It is a beautiful dark eggplant color, but not what it was supposed to be. I fired the the load to ^6 with a slow cool (medium down to low then off to finish) it was a load of only reds and red/blacks. Refiring perhaps or not firing it with reds? I think I need to change my user name to the Frustrated Firer!

[Les]

I have used this glaze twice, each time at ^6 electric oxidation, and both times it has produced a muddy brown color. I did notice the red starts to come out where the glaze has been applied thicker. None the less, I was disappointed in it and don't intend to use it again. After all, how many bisque pieces can you afford to lose?

It would be nice to have a glaze techie from Amoco chime in on this. Do you think they read our comments? I sure hope so. It would be nice if all the suppliers actually tried to help point us in the right direction every once in a while. This glaze is new, so perhaps we'll hear from them.

[azjoe]

... It would be nice if all the suppliers actually tried to help point us in the right direction every once in a while.

Yes, it would... but in my experience they don't reply to questions emailed to them directly, so I wouldn't hold my breath that they will post here. I wouldn't treat my customers that way, but I guess that's pretty old-school these days.

[Pam S]

Well, that is disappointing.

[cracked pot]

I just took a load out of the kiln and three pieces were in Ancient Jasper. I read somewhere online, don't remember where, that the glaze needs to be fired to cone 5 fast and cooled fast to achieve the red color. I fired to cone 6, slow glaze and placed the pieces where I thought it would be cooler in the kiln. They came out with shades of olive green, dark blue and orange. Quite beautiful. The pieces also need texture for the glaze to break. Don't give up on it yet.

[Mark]

Has anyone tried this glaze? I just took Ancient Jasper out of the kiln. It is a beautiful dark eggplant color, but not what it was supposed to be. I fired the the load to ^6 with a slow cool (medium down to low then off to finish) it was a load of only reds and red/blacks. Refiring perhaps or not firing it with reds? I think I need to change my user name to the Frustrated Firer!

I absolutely love this glaze and has become a favorite of my clients. The problem that you are having is that you are not applying it thick enough. When I make or purchase a new glaze I always run a test piece putting rings of glaze starting with one coat at the bottom and then two, three and four, I top it off with a thick rim to get a drip break. What I found is that to get a more solid red you need to apply four heavy coats, if you only apply three coats then you get the dark almost black look. What I prefer is to apply three even coats and then apply a mottled coat so that some of the darker breaks come through, see attached picture. I fire to cone 6 oxidation.

Mark

Attached Files

•  3 + 1 mottled coat.jpg   140.28KB   666 downloads
•  4 coats Ancient jasper.jpg   157.44KB   721 downloads
•  2 coats with rim drip coat.jpg   175.21KB   554 downloads

[Pam S]

Ahh! Mark! Those are beautiful! Are you dipping, brushing or spraying? Thanks for the input! I will try it again!

[Steve Lampron]

ANCIENT JASPER: Hello all and stay with me as I am and old guy and not blog capable. I am the VP of Technical Services here at AMACO and the engineer that developed this glaze. I am very sad to hear that some of you are having difficulty with this glaze. It is actually a very easy glaze to work with and will yield excellant results. Let me give you a few tips on this type of glaze in general an then some specifics about ANCIENT JASPER.
Many midrange and high fire glazes used by ceramic artists are what I call FLOAT glazes. These are the pretty glazes that tend to seperate out different colors in areas where the glazes are thicker. ANCIENT JASPER is this type of glaze and what it floating out is iron oxide. Iron is one of the more interesting colorants simply because it can be in so many different oxidation states. This simply means that it can make a ton of different colors. With any float glaze, enough thickness of glaze must be applied in order for the excess iron to float to the surface. If the glaze is thinly applied, the glaze will tend to be drier and a very unpleasant color.
This glaze was not developed where any massive amount of glaze needs to be applied. If it had needed this I would have told everyone on the label. We actually never had any issues getting red at all. I always try new glazes on all of our clay bodies to make sure there isn't some issue I need to know of. We also fire them at cone 5 and cone 6 to check stability. We found no issues with this glaze on either account. By now you probably saying, great but it didn't work for me. I will list some good parameters below for you to follow and I am 100% sure you will find this glaze simple to use and that it will yield great results.
1. Temperature: The red color is actually the first color to float and the use of more heat will tend to make it turn to the purples, yellows, browns and black. This means you will tend to see slightly (and I do mean slightly) more red at cone 5 than cone 6. No soak is needed for this glaze and actually soaking it will cause more red to fade into the other colors.
2. Thickness: The glaze must be applied with enough thickness to float the iron.
3. Kiln cycle: I fire all the glazes we develop in an electric kiln at fast, medium and slow speeds. Red color will be developed at all speeds but the faster the firing ~6 hours (tons of red) the better the results. I always quality check each batch at cone 5 in 8 hours. 10-12 hour cycles will cause more red to fade to the other colors. This is most critical within 200 defrees of peak. If your elements are weak and it takes the kiln a long time to achieve the last 200 degrees, you will find less red.
4. Cool down: No special cool down is needed nor will it help develop any red color. Letting the kiln simply shut off and cool naturally is all that is needed.
4. Clay Body: I have tested this on porcelain, typical stoneware bodies, bodies with grog, bodies without grog, brown colored bodies, etc. I develop red on all of them. I have found that when using our #1 Porcelain slip that the color transition away from the red tones is very pronounced (although it makes a rainbow of the other colors). This is because for a cone 5 porcelain slip alot of soft flux is needed to tighten the body. The flux in the body mixes with the glaze and actually makes the glaze softer (simulating more heat).
5. Texture: This glaze loves texture and will make some incredible colors. The texture makes the glaze get thinner and thicker in areas. The thicker the glaze the easier it is for it to stay red. The thinner the glaze gets the hotter that area of glaze gets and it shifts to the other colors.

These simple tips should help everybody that wants to make ANCIENT JASPER work. I suggest running a few tests of glaze thickness in your next kiln load and follow the firing rules above. Three nice coats on any typical stoneware body, fired to cone 5 or 6 in 6-8 hours with no soak and no special cooling curve will yield pieces just like the ones we showed in the ads. These were just pots we made in the lab. Honestly I have never actually made a pot that didn't make colors just like those pieces.
I will attempt to post a few more photos here today and next week we will post a board I made with all of our clay bodies fired at slow, medium and fast so you can see the slight differences.
Let me know if this helps.
The photo files are too big to upload. I will have someone help me make them smaller for next week.
Steve.........

[Steve Lampron]

Guys,


These are photos of a pot made by Danny Meisinger of Spinning Earth Pottery. It shows how the red naturally breaks to other colors around texture.

Steve............  IMG_0412web.jpg   27.33KB   532 downloads  IMG_0276web.jpg   25.55KB   490 downloads





Sorry the pictures have to be so small to upload.

[Pam S]

A great big THANK YOU to Steve! I'm not trying to chide anyone, but this really need to happen more often with the use of commercial products. We are a community!

[azjoe]

ditto what Pam said!! Thank you so much Steve for posting info that helps us use your glaze successfully (and three cheers to Amaco for having you support their products within the user community).

[cracked pot]

Thank you Steve! I love this glaze and everyone who see it comments on it. It's wonderful to have more detailed application information.

[Steve Lampron]

You are all very welcome. I don't like anyone to struggle with one of my creations. I am also glad you all like the look of ANCIENT JASPER.

Steve...........

[Les]

Thank you Steve, so much. I was the poster that lamented the lack of any manufacturer's help, but you and Amoco proved me wrong. I can't wait for your pictures to arrive. In the mean time, I am going to purchase another pint of Ancient Jasper and follow your suggestions. I'm looking forward to good results. For the record, I am a big fan of the entire Amoco PC line, and highly recommend them for potter's that work with glazes "out of the jar". Thanks again.

[Pam S]

It's great to know that the manufactures are listening to us! Good customer service equals happy customers! Happy customers equals better sales! And on and on...

[Pam S]

Just opened the kiln. I fired it fast with no soak, low for an hour, medium for an hour. When I started seeing red I closed the peeps and lid. About 5 hours until the cones dropped. The witness cones were perfect. The Ancient Jasper was green with only hinds of red (last time it was more of a dark eggplant purple with green). My thought is that I'm not applying the glaze thick enough...

[Steve Lampron]

Pam,

May I suggest that I think you are correct in your assumption that you do not have enough glaze applied. I am going to tell you my thoughts on using any new glaze. I would make 6 small test tiles or extrusions (which ever is easier) out of your clay body. Glaze two of them with what you think is the correct amount of glaze (as recommended by the manufacturer and using your glazing technique), glaze two with what you think is not enough glaze and two with what you think is too much glaze. Make sure you actually make an appreciably different application of glaze on the three sets. Fire one of each application thickness laying down (simulates a plate, etc) and fire the other three standing up vertically (simulates a cup or bowl). Make sure you put them on a scrap piece of shelf in case they flow. In firing these pieces you will not only learn what the glaze looks like when it is correct, but you will also find out what it looks like when it is wrong. You will also see the amount of flow you might expect on pieces so you can compensate for this on your ware. Some glazes will show some very distinct differences in all these different applications and firing orientations and others will show very little. Hope this helps.


Steve.........

[Pam S]

I keep little pinch pots of various sizes and shapes around to test glazes on. Next glaze firing I'm going try a couple with what looks like too much and way too much;0) At least the last ones were showing the reds. I refuse to give up on this glaze as I love the look of it when done properly! Thanks for your help. Just as a FYI, I just ordered a pint of AMACO Palladium to try. I saw a piece done in that glaze and my jaw hit the floor, it was that gorgeous!

[terracotta]

I have used this glaze, I got a very bright dark red color with dark blue in textured areas. I applied two thick coats by dipping--it ran alot. Be careful not to get too hot or thick. I had to remove it from kiln shelves. I fired it to cone 6 using the firing schedule from Mastering cone 6 glazes. I will try again, but in a cooler spot of my kiln. I was a bit disappointed, I just haven't found that magical way of firing it yet.

[giltex]

Bought this glaze about a month ago and read all of the comments on the forum. This came out of the kiln after my first firing with it. I brushed three heavy coats then dabbed some highlights.

Attached Files

•  candle.jpg   17.44KB   415 downloads