•The secret to cool bodies and glazes is a lot of testing.
•The secret to know what to test is material and chemistry knowledge.
•The secret to learning from testing is documentation.
•The place to test, do the chemistry and document is an account at https://insight-live.com
•The place to get the knowledge is https://digitalfire.com
It is difficult to draw a line between what is matte and what is semi-matte (also known as soft matte) from a visual inspection point of view. However from a production point of view it is much easier. Glazes generally want to be glossy (the vast majority of random glaze formulations are glossy). Matte glazes, on the other hand, are difficult to create, there is a narrow range of chemistries wherein matte effects will develop such that the glaze is still well-melted and does not cutlery mark or craze.
Matte glazes can be such because of a micro-rippled light-scattering surface, because of crystallization or because of phase changes that scatter light, each mechanism has its own firing and process challenges to maintain. Companies generally configure their process to make the glaze as matte as possible while still having good technical properties (actually some do relax the technical properties and tolerate some cutlery marking, for example). A semi-matte is a relaxing of the stringent requirements of the matte effect, a movement toward an easier-to-manufacture, but glossier product (as opposed to stony mattes which compromise functionality for even more matteness). The semi-matte space is quite volatile, small chemistry changes, or even more important, firing changes, can produce large shifts in gloss of the fired glaze. Companies can measure the amount of semi-matteness by measuring the amount of reflected light from a glaze surface or comparison of surface micrographs.
How to matte Ravenscrag Slip at cone 10 by adding talc
2,5,10,15% talc added to Ravenscrag Slip on a buff stoneware fired at cone 10R. Matting begins at 10%. By Kat Valenzuela.
2, 5, 10, 15% dolomite added to Ravenscrag Slip at cone 10R
This is a buff stoneware clay. Crystal development toward a dolomite matte begins at 15%. By Kat Valenzuela.
An incredible silky matte surface supports wild colors at cone 6 oxidation
This is the G2934Y matte base recipe with only 8% Cerdec Orange encapsulated stain. G2934Y employs a frit-source for the MgO (as opposed to G2934 which sources the MgO from dolomite). The orange color is brighter on the mug on the left because the porcelain is whiter, Plainsman Polar Ice (the other one is #6 Tile Kaolin based, P300). If this was a glossy glaze the required percentage of stain would be higher. Other colors, like yellow, are equally vibrant. But not all, testing is needed.
Out Bound Links
A glaze that is not glossy. Of course, unmelted glazes will not be glossy, but to be a true matte a glaze must be melted and still not glossy. To be a functional matte it must also resist cultery marking, clean well and not leach into food and drink. Thus it is not easy to make a good matte glaze. I...
G1214Z Cone 6 Matte Base Glaze
This glaze was developed using the 1214W glossy as a starting point. This article overviews the types of matte glazes and rationalizes the method used to make this one.
In Bound Links
G1947U/G2571A Cone 10/10R Base Matte/Glossy Glazes
These starting recipes use no frits and work in oxidation/reduction and are inexpensive to make. They can be used as bases for the whole range of typical cone 10 pottery glazes (celadon, tenmoku, oatmeal, white matte, brown crystal).
'Gloss' refers to how shiny and light-reflective a glaze is. Glazes high in glass former (SiO2, B2O3) are glossy. Those high in Al2O3 tend to be matte. Fluid glazes can crystallize to a matte surface if cooled slowly or a glossy surface if cooled quickly. The SiO2:Al2O3 ratio is taken as a general i...
Dolomite matte glazes are normally fired around cone 10 and have a pleasant-to-the-touch silky-feeling surface. The name has stuck because dolomite has been the most common source of the oxide needed for the effect: MgO (although other materials can also source it, especially talc). The unique feel ...
Formulating a Cone 6 Silky Matte Glaze at Insight-Live
Silky Mattes are much more difficult at cone 6 than at cone 10
They are fragile: It is common to find mattes that either gloss on slight over-firing or are too matte and cutlery mark, stain and craze...
G2934 - Matte Glaze Base for Cone 6
A base MgO matte glaze recipe fires to a hard utilitarian surface and has very good working properties. Blend in the glossy if it is too matte.
2014-03-26 - A cone 6 boron-fluxed MgO matte developed at Plainsman Clays by Tony Hansen (a link below will take you to its page there). This page contains technic...
By Tony Hansen