Stuey88 Posted August 7, 2011 Report Share Posted August 7, 2011 Hi all, I'm relatively new to glazing... I'm wondering whether it is possible to make a perfectly TRANSPARENT glaze up to AN INCH THICK. A friend of mine (equally inexperienced in glazing) tried a series of recipes, but either through under-firing or something else, they remained fairly opaque. I was hoping that someone knows of a successful recipe for making such a thick transparent glaze, and the firing procedure involved. Any help on the matter would be really appreciated. Stu. Link to comment Share on other sites More sharing options...
Chris Campbell Posted August 7, 2011 Report Share Posted August 7, 2011 I am not a glaze genius, but the properties of light itself would make this a daunting task. I would guess you would have to have every inch of this glaze so perfect and consistent that a light beam could go straight through it without any bouncing or reflecting. Out of shear curiosity ... Why? Link to comment Share on other sites More sharing options...
Guest JBaymore Posted August 7, 2011 Report Share Posted August 7, 2011 Matching the reversible Coefficient of Thermal Expansion to the underlying clay body is the first part of the "technical hurdles" you are going to face. With a really thick layer of glaze like that, it is going to be imperative that it and the clay body contract at the same rate once the glaze liquid has frozen. Otherwise the compression from the glaze is likely to crack the body (unless it too is massively thick) or the glaze is going to craze and blow your "clear" qualities. As a general comment here.... it is going to require a much longer firing cycle than that appropriate for thinner coatings of glazes. You will need to give time for all of the outgassing and then the tiny bubbles to rise to the surface and disburse. This is usually called "fining out"....a glassblowers teerm. I'm with Chris.... why? best, .............john Link to comment Share on other sites More sharing options...
Stuey88 Posted August 8, 2011 Author Report Share Posted August 8, 2011 Thanks for the replies,The reason I need such a thick, transparent layer is rather difficult to explain without giving a 2 page report with graphs and figures... In short, the glaze is not filling some aesthetic, artistic need. It's purpose is more physics-based. The glaze is being applied to a material to be placed outdoors, with it's function being to allow the Sun's radiation to pass through it uninhibited, whilst acting as a barrier from low temperature winds. The reason I need the glaze to be so thick is what is difficult to explain in short... I am yet to confirm whether it is possible, but I might be able to reduce the thickness to ~5mm in an attempt to make the glazing procedure much easier. Am I correct in assuming that this will make the whole ordeal easier? Does anyone, therefore, have any successful recipes + procedures for a clear gloss glaze with a thickness of 5mm? I'm sorry if I haven't explained the problem very well... The problem is a rather unique one I think... Thanks again for the help. Link to comment Share on other sites More sharing options...
missholly Posted August 8, 2011 Report Share Posted August 8, 2011 it would be interesting if you could just dip the item in molten glass. Link to comment Share on other sites More sharing options...
Guest JBaymore Posted August 8, 2011 Report Share Posted August 8, 2011 it would be interesting if you could just dip the item in molten glass. Unfortunately the COE of true glass and the COE of clay are quite different. best, ....................john Link to comment Share on other sites More sharing options...
Guest JBaymore Posted August 8, 2011 Report Share Posted August 8, 2011 The glaze is being applied to a material to be placed outdoors, with it's function being to allow the Sun's radiation to pass through it uninhibited, whilst acting as a barrier from low temperature winds. Why are you tied to a fired, ceramic solution? Have you considered any of the possible acrylics and the like? best, .....................john Link to comment Share on other sites More sharing options...
Chris Campbell Posted August 8, 2011 Report Share Posted August 8, 2011 Yes, you have tantalized our creative minds ..... It sounds as though you are trying to capture heat while blocking cold winds ... Alternative energy idea? Link to comment Share on other sites More sharing options...
Guest JBaymore Posted August 8, 2011 Report Share Posted August 8, 2011 There wouldn't be a ceramic photovoltaic substate involved in this somewhere, would there? best, ..................john Link to comment Share on other sites More sharing options...
Marcia Selsor Posted August 8, 2011 Report Share Posted August 8, 2011 john's mentioning of the C.O.E. is important, but in more simple terms...usually the thicker the transparent glaze is applied , the milkier it becomes. that usually refers to a thckness of perhaps 1/16 of an inch or more. The thickness you are contemplating would shatter the pot if it were on the inside of the piece because of the differences in the C.O.E. if it were on the outside of the pot, it most likely would run off. marcia Link to comment Share on other sites More sharing options...
John Britt Posted August 9, 2011 Report Share Posted August 9, 2011 You can try a high feldspar glaze like : 85Custer Feldspar 8 Silica 7 Whiting for a start. Johnbrittpottery@gmail.com Link to comment Share on other sites More sharing options...
Guest JBaymore Posted August 9, 2011 Report Share Posted August 9, 2011 All of us are forgetting to ask a basic, crucial question here......... What cone end point are you planning to use? best, ........................john Link to comment Share on other sites More sharing options...
Stuey88 Posted September 6, 2011 Author Report Share Posted September 6, 2011 Hi all, sorry for my almost month-long hiatus, I was trying a particular recipe for this problem... Sadly it did not work. I have, however, confirmed that the glaze need only be around 3-5mm (~0.12-0.20in). In response to a few of your questions... Why are you tied to a fired, ceramic solution? Have you considered any of the possible acrylics and the like? Are you referring to acrylic paints? or acrylic type plastics (eg. perspex)? I'm assuming you're referring to the latter as I am unaware of a transparent acrylic paint (I could very well be wrong there though). With regard to perspex, I ruled it out in the early stages of this project as I was looking for something that was commonly fixed to a clay material (in my case, it's a brick). Do you know if perspex can be applied in this type of scenario? Yes, you have tantalized our creative minds ..... It sounds as though you are trying to capture heat while blocking cold winds ... Alternative energy idea? Exactly right, the aim is to allow heat to radiate through, while blocking the cold winds. I'm not sure if I've mentioned this earlier, but the glaze is being applied to a slightly modified clay brick. The purpose of the glaze is to allow the Sun's radiation to heat up the brick underneath, while preventing the cool winds from physically touching the brick itself. The glaze doesn't necessarily have to be glaze, it was merely the most practical solution that came to mind during the conceptual phase. Whatever the substance, it needs to be able to bond to the brick. There wouldn't be a ceramic photovoltaic substate involved in this somewhere, would there? Haha, no no. Merely trying to adopt the principles of passive solar efficiency. All of us are forgetting to ask a basic, crucial question here......... What cone end point are you planning to use? Hadn't planned on a particular cone. Doesn't this depend on which glaze is chosen? I am happy to adapt to whatever recipe works. So to summarise, the revised glaze need only be ~0.12-0.20in, however, my initial tests are still having poor results with regard to transparency. Thanks for the help. Stu. Link to comment Share on other sites More sharing options...
OffCenter Posted September 6, 2011 Report Share Posted September 6, 2011 You can try a high feldspar glaze like : 85Custer Feldspar 8 Silica 7 Whiting for a start. Johnbrittpottery@gmail.com What cone? Link to comment Share on other sites More sharing options...
Chris Campbell Posted September 6, 2011 Report Share Posted September 6, 2011 Another question for you ... Why do you think the glaze has to be transparent for it to absorb heat? Or is this just for appearance? Link to comment Share on other sites More sharing options...
Stuey88 Posted September 7, 2011 Author Report Share Posted September 7, 2011 Believe me, this is definitely not for a appearances... This thing is uglier than you could imagine... The glaze itself is not intended to absorb heat. Its purpose is for the heat to bypass the glaze, while acting as a barrier to the cool winds. It needs to be transparent so the Sun's radiation will transfer through to the brick underneath, rather than reflect off the surface. If the glaze were opaque, the Sun's light would reflect off the surface of the glaze, and it would mean only the surface of the glaze itself would be exposed to the heat source, and thus the entire glaze would need to heat up enough to reach the brick underneath. The winds cool down the surface of glaze, negating much of the heat gained from the Sun's radiation. I'm not sure if I've explained that well enough, but to summarise - yes, it needs to be transparent unfortunately. Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.