[yedrow]

At this point in my career I'm beginning to notice a phenomenon that I'm calling the pottery no-man's land. I define it as that place between the use of radiant glazes that so coat the piece that they destroy the surface and glazes that are aesthetically unified with the pot and in so being amplify the beauty of the piece. Between those 'conditions' there seems to be an area where one's pots won't sell regardless of the perfection of form. Most of the glazes I've used have been created by other people and adjusted for the kiln at work. They are thick and do a good job hiding the flaws of the beginners we hire. But when surface is added they glob over it and I end up with something that looks more like a partially used Jolly Rancher.

Has anyone out there had this kind of issue? If so, how did you get past it, and how long did it take?

[trina]

yedrow, on 08 February 2012 - 11:28 AM, said:

At this point in my career I'm beginning to notice a phenomenon that I'm calling the pottery no-man's land. I define it as that place between the use of radiant glazes that so coat the piece that they destroy the surface and glazes that are aesthetically unified with the pot and in so being amplify the beauty of the piece. Between those 'conditions' there seems to be an area where one's pots won't sell regardless of the perfection of form. Most of the glazes I've used have been created by other people and adjusted for the kiln at work. They are thick and do a good job hiding the flaws of the beginners we hire. But when surface is added they glob over it and I end up with something that looks more like a partially used Jolly Rancher.

Has anyone out there had this kind of issue? If so, how did you get past it, and how long did it take?

Hard question to answer but i think you answered it yourself, you are using glazes that have been created by other people, and it suits them. Maybe you need to start mixing and testing your own glazes and get one that is right for you. Yes I KNOW this takes ages but in the learning you will create something for you and by you. Trina

[Chris Campbell]

Could you post images showing examples ... Be great to see what you are asking!

[yedrow]

Quote

Hard question to answer but i think you answered it yourself, you are using glazes that have been created by other people, and it suits them. Maybe you need to start mixing and testing your own glazes and get one that is right for you. Yes I KNOW this takes ages but in the learning you will create something for you and by you. Trina

The vase section is a glaze that enhances and amplifies the surface of the pot.

 2012-02-08 12.33.16.jpg (1.46MB)
Number of downloads: 147

The mug shows a glaze that destroys the surface by globbing over any treatments and blunting curves and corners.

 2012-02-08 12.34.19.jpg (1.2MB)
Number of downloads: 145

[Chris Campbell]

The world of glazing is not only choosing the right glaze for the piece, but knowing how thick it should be in the bucket as well as how thick the application should be on the pot. That mug might have looked ok if the glaze had been applied thinner because it does not look bad where it breaks on the edges.
Knowing all these things takes years so that is why production potters narrow down their glaze choices and learn how, when and why to use them.
Get a good glaze book, look at the images, decide on two or three to experiment and learn from.

Also, thick glazes do not hide beginner mistakes ...
Quick question and really none of my business ... Why are you hiring beginners?

[yedrow]

Thanks for the suggestions. I certainly am not a glaze guy yet. However, I've noticed that glassy glazes tend to go on thick. For instance, I've never seen a thin glassy oxblood red. I work in a production pottery and have never actually seen a thin feldspathic glaze look good in a functional sense if applied thin. Who knows what the future will bring though.

I'm at the point in my development that my forms are getting strong. I do want to begin work on glazes and am reading about glazes and glaze chemistry continuously. At present I'm working at home on some of Ron Roy's glazes from, "Mastering Cone 6 Glazes." Unfortunately most of the glazes I've seen do little to amplify the surface of the actual pot. The Stony Blue in the picture of the vase is a great glaze. But the rest of our glazes either obscure the surface or distract from it and become their own surface. I guess what I'm aspiring to is developing or finding glazes that act like the Stony Blue in that they 'fit' the pot closely and integrate compositionally with the pot in a continuum sense.

I had the great good fortune of being hired with no experience. The shop will occasionally hire people like that, but mostly we've hired second and third year collage students. Either way, off the street or out of a college their work looks the same in the end, as a matter of production/functional value and expression. There otherwise aren't other people to hire. I've seen potter's who've done this for over ten years come into the shop and make the same mugs people who've done it for two months make. When it comes to production 'beginners' vastly outnumber those who are experienced I guess.

[TJR]

yedro;
This question of yours is a tough one. I credit Chris for taking it on. When I glaze, I always count to 5. As in five seconds with the mug completely immersed in glaze. I also use glaze tongs. There is a tool for measuring the specific gravity of a glaze. Can't think of the name at the moment. That mug looks like the glaze is on way too think. This is a problem with division of labour. As my sainted mother would say; "If you want anything done, do it yourself."
So maybe you need to do the glazing if you are not satisfied with the work of others.
TJR.

[Chris Campbell]

I don't know if you are the owner or a crafts person at this pottery but I would suggest you hire the consulting services of a glaze guru ... It will take you years to find the ever illusive perfect fit .. perhaps one of them could jump start it. Kind of like hiring an experieced chef to tweak the restaurant menu.

[Mark C.]

working on others suggestions-
The glaze hydrometer is how you measure specific gravity of a glaze (thick or thin)-its a glass tube and costs about 20$
You need one to get it always the same-you can as I was taught see how it runs off your hand but the hydrometer is more accurate-plus I wear latex gloves past 20 years with all glazes which makes it harder to gauge

Chris's suggestion on a glaze consultant is a great idea
This Tile company has a fellow I know who does that for them-I just forgot his name at this time-(he went to school with my brother in ceramics back in the late 60''s)
Call Macintyre tile and ask for the glaze consultants phone# he works for many different ceramic places.
http://www.mcintyre-...ut/our-approach
Hope these help
Mark

[JBaymore]

Mark C., on 10 February 2012 - 12:41 PM, said:

working on others suggestions-
The glaze hydrometer is how you measure specific gravity of a glaze (thick or thin)-its a glass tube and costs about 20$
You need one to get it always the same-you can as I was taught see how it runs off your hand but the hydrometer is more accurate-plus I wear latex gloves past 20 years with all glazes which makes it harder to gauge

Actually a hydrometer is of limited use in most glaze slurries. Among other things, it measures only one aspect of the material. The rheology of the slurry is far better controled for application purposes with a viscometer. Standard in industry.

Fancy word there.... but basically a viscometer is just a container with a hole in it. You track the amount of time it takes a fixed volume of the glaze slurry to flow out of that hole with a stopwatch. Mix a specific glaze to that number every tinme and if the bisque cone is the same and the clay body is the same and the cross section of the walls of the piece are the same ... if you dip for 5 seconds.... you'll get the same thinckness of application.

It takes into account more than just the solids weight ratio to the water.

If you don't care about comparing to industry numbers..... or other potters results.... you can make one yourself with a coffe can and a drill. If you want results that match up with the industry number standards... you should buy a unit.

best,

..................john

[Matt Oz]

JBaymore, on 10 February 2012 - 03:48 PM, said:

Mark C., on 10 February 2012 - 12:41 PM, said:

working on others suggestions-
The glaze hydrometer is how you measure specific gravity of a glaze (thick or thin)-its a glass tube and costs about 20$
You need one to get it always the same-you can as I was taught see how it runs off your hand but the hydrometer is more accurate-plus I wear latex gloves past 20 years with all glazes which makes it harder to gauge

Actually a hydrometer is of limited use in most glaze slurries. Among other things, it measures only one aspect of the material. The rheology of the slurry is far better controled for application purposes with a viscometer. Standard in industry.

Fancy word there.... but basically a viscometer is just a container with a hole in it. You track the amount of time it takes a fixed volume of the glaze slurry to flow out of that hole with a stopwatch. Mix a specific glaze to that number every tinme and if the bisque cone is the same and the clay body is the same and the cross section of the walls of the piece are the same ... if you dip for 5 seconds.... you'll get the same thinckness of application.

It takes into account more than just the solids weight ratio to the water.

If you don't care about comparing to industry numbers..... or other potters results.... you can make one yourself with a coffe can and a drill. If you want results that match up with the industry number standards... you should buy a unit.

best,

..................john

Are you saying that a viscometer is also better to use then weighing a 100ml sample, or are they both used.

[JBaymore]

Matt,

Yup.... skip the hydrometer or the pint weight. Use the viscometer.

best,

.................john

[Matt Oz]

Thank you

[bciskepottery]

Our studio uses many of the Mastering Cone 6 glazes; some are very good on textured surfaces, others are not. It's mostly a matter of trial and error to see which ones, and which combination of glazes, produce the effect you are looking for on your work.


From reading the Clayart listserv, it seems Ron Roy is willing to work with folks who are looking to tweak his glaze recipes. Might be worth shooting him an email, explain what you are looking for, and asking him for suggestions, advice: ronroy@CA.INTER.NET

[Mark C.]

JBaymore, on 10 February 2012 - 03:48 PM, said:

Mark C., on 10 February 2012 - 12:41 PM, said:

working on others suggestions-
The glaze hydrometer is how you measure specific gravity of a glaze (thick or thin)-its a glass tube and costs about 20$
You need one to get it always the same-you can as I was taught see how it runs off your hand but the hydrometer is more accurate-plus I wear latex gloves past 20 years with all glazes which makes it harder to gauge

Actually a hydrometer is of limited use in most glaze slurries. Among other things, it measures only one aspect of the material. The rheology of the slurry is far better controled for application purposes with a viscometer. Standard in industry.

Fancy word there.... but basically a viscometer is just a container with a hole in it. You track the amount of time it takes a fixed volume of the glaze slurry to flow out of that hole with a stopwatch. Mix a specific glaze to that number every tinme and if the bisque cone is the same and the clay body is the same and the cross section of the walls of the piece are the same ... if you dip for 5 seconds.... you'll get the same thinckness of application.

It takes into account more than just the solids weight ratio to the water.

If you don't care about comparing to industry numbers..... or other potters results.... you can make one yourself with a coffe can and a drill. If you want results that match up with the industry number standards... you should buy a unit.

best,

..................john

I have measured my slip for years with a viscometer and a second timer John-I'll bust it out now with my touchy glazes-great to learn new/old stuff
I only have a few that need this fine tuning.
Mark

[yedrow]

Chris, actually I've consulted Jeff Zamek before and am getting a list of questions together that I might call him again. Thank for the good advice.

Mark, thanks for the suggestion and the link. I both use a hydrometer and weigh my glazes but as JBaymore said, the rheological properties of the glaze make a huge difference in the flow of the water into the bisque and thus the thickness of the glaze (as I understand at least). Some glazes flocculate different than others and balancing that flocculation is tough. The Stony Blue in the pic actually cannot be adjusted to my knowledge, at least in the sense of making it "fatter". I suspect much of the 'tricks' to getting a good glaze lie in the nature of the ratio of metal alkalies to earth alkalies in the melt and the thixatropy of the slurry in the application, and in some eutectic way the the balance between the two gives you a workable glaze. This is assuming of course that the metal alkalies in general interfere with the bonding, or flocculation, of the clap particles. For now though these are just concepts to me, I truly am just beginning to get an idea of what a glaze really is.

JBaymore, actually, I have been haphazardly looking for a viscometer for a couple of weeks. I will redouble my efforts!

Bciskepottery, you know, I think I'm going to do a couple more test firings and send Mr. Roy an email. Thanks for the info.

Thanks everyone. I wish I had found this site years ago.

[JBaymore]

yedrow, on 11 February 2012 - 03:46 AM, said:

JBaymore, actually, I have been haphazardly looking for a viscometer for a couple of weeks. I will redouble my efforts!

Bciskepottery, you know, I think I'm going to do a couple more test firings and send Mr. Roy an email. Thanks for the info.

yedrow,

Just make one for the time being. Metal can and drill a hole in it. Debur the hole with a file. As long as you compare the sucessful mixture to the new mixture using your own numbers.... it is absolutely accurate for this kind of usage.

Here's a really cheap "flow cup" viscometer version:

http://www.sheffield...p/mayvc497p.htm

Here's a better version:

http://www.janecosal...tycupzahn2.aspx


And here's the top level of the ones I'll list:

http://www.capitolsc...px?item=P1060-2


If you want really accurate "industry reliable" numbers you want what is called a torsion viscometer.... but that'll set you back almost a Grand. Uses the unwinding of a spring loaded cylinder suspended in the glaze to measure the viscosity. Usually serious overkill for us studio type folks....... like getting rid of a mouse with an AK47 on full auto.


If you talk to Ron (Roy) tell him I said "hi". We "go back" a bit... presented with him on a glaze panel at NCECA, etc. He's good folks..... really knows his stuff.

best,

.................john

[JBaymore]

I took the liberty of moving this thread to the "Technical" section from the "Aesthetics" section, since the direction it really was taking was more along that nature of things than focusing on more pure aesthetic concerns. Hope everyone is OK with that. Please keep talking about it there.

best,

....................john

[yedrow]

JBaymore, I'll tell Mr. Roy you said Howdy.

If making a viscometer about what would be the best dimensions of the cup and what size of drill bit should one use. I think I just need things standardized within my shop.

Hopefully I'm not asking too many bothersome questions, but...In my mind these things are based on some central point of reference. In this case that is going to be the diameter of the hole. Then, I test each glaze for flow, wet them, then test again until I get the finished glaze I'm seeking. But, if I flocculate the glazes (muratic acid for instance), or increase the surface tension with Veegum T or such, does that add an extra dimension to the test. Hopefully I'm phrasing this correctly. I can either wet the glaze or allow it to dry/remove water to effect the consistency of the slurry, or I can flocculate it or increase the surface tension to effect the consistency. Will these choices effect the 'point of reference' nature of the orifice, either used alone or in unison?

I'm not meaning to ask a pesky question. The answer will answer other unrelated questions as well though.

[yedrow]

My apologies it the preceding post was difficult to understand. I haven't been getting much sleep this week and I'm kind of muddled.

What size of hole should the orifice be? I'm figuring somewhere in the range of 1/8 inch. And, do the cups need to be any shape or size in general? I'm remembering this thing about pressure at the bottom of a column of water (from high school).

Please correct me if I'm wrong but: It seem as if one of the 'tricks' to getting a glaze to work lie in the solubility of alkalies in the slurry combined with the activity of those fluxes in the melt, and what part/portion of either can be modified to make the other work. At some point the nature of the slurry must be changed. Logically, the least consistent glazes must be changed the most.

Flocculating the glaze changes the viscosity and in so doing changes the capacity of water to move from the surface of the coat into the bisque (leaving a wet sheen on the newly glazed bisque). Glazes that have more solubles (need more flocculation) should be more finicky. As well, using CMC or Veegum T alters the rheological properties of the slurry and the volume that will adhere to the bisque per second of dipping. Also, when water is added to the slurry the internal viscosity is changed as well.

Changing the viscosity by adding water should give a linear like change in the flow through the viscometer and be the baseline change. My question is: Do changes from flocculants and materials like Veegum T effect the measurements of the viscometer in the same way as simply adding water does, especially if both or all are used on the same glaze?

Thank you for any help you can give on this. However, if I should be consulting a for fee expert for this type of question then I apologize. I'm just getting into the glaze thing and can't get enough information.