Using glaze in powdered form

[Frenchie Argent]

I recently researched old tile making processes and keep running into the use of sprinkled powder glazes on top of the tiles before firing. Can I use any powdered glaze mix before adding water to do this? ( I found this online/“Glaze may be applied by dry-dusting a dry mixture over the surface of the clay body...”)

[StonedStudio]

"Glaze" is just a raw mixture of materials thats suspended in water for the application process.

You can dust those materials over a piece. It's just a different application process. It's just likely to be much messier, and wont stick as well.

[Hulk]

Hi Frenchie!

Good question. The quote above - the source article has been reposted many many times...

In my process, slurry is the way to go, no contest - works for non-horizontal surfaces, sticks well, allows for somewhat precise application, doesn't blow around.

Am finding that adjusting glaze specific gravity (how much water) and thixotropy* helps, also practice.

 *Thixotropy and How to Gel a Ceramic Glaze (digitalfire.com) See also several threads on the topic in this forum.

[Callie Beller Diesel]

It sounds like this website may have been one with an archeological basis or interest, rather than one that involves current practices. It was once a common to dust raw pots with powdered lead. But we don’t do that anymore, because it’s not real good for your long term health. One of the reasons bisquing is a thing is so that we could use glaze slurry, which keeps the dust down and is faster, as well as all the reasons Hulk mentions. 

 In theory, yes, you could apply powdered commercial glaze that does not include lead to raw pots, but it seriously increases  inhalation exposure to things like silica, or heavy metals that are used for colourants. Our greatest workplace hazards come from kiln fumes, or dusts. I could also see it being more difficult to control than something like a glaze sprayer that you can direct.

 

[Frenchie Argent]

The reason for the dry glaze... I am trying a William De Morgan’s technique of applying porcelain slip to bisque tile and then sticking a piece of paper with the colored image (painted in glaze) to the slip with sodium silicate. When I applied the last step using the liquid glaze, it made the paper rewetted and it lifted a little from the slip. So his process put dry glaze, maybe because of the rewetting problem... all the old information never went into details about this... so I can just take my powdered glaze and sprinkle it... ???

[Min]

I'm sure you've read a lot more on this than I have but from this link it looks like that's not quite what he was doing, at least at one point. From the excerpt below it sounds like he transferred the text from a master using pigments (which I'm thinking would be china paints, enamels or oxide solutions) onto the transfer paper then placed that onto the slip coated tiles (leather hard slip? dry slip?) which were left in place and then glaze. I'm not sure what the purpose of the sodium silicate would be, maybe to glue it all together? Is there info on dry glazing somewhere else?

Welcome to the forum!

"Described by William in a letter to his business partner Halsey Ricardo in 1895: after using the glass to help transfer the pattern from the master design to paper, pigments would be applied and the painted paper then placed face down onto slip-coated tiles, coated with glaze and sodium silicate and fired. The paper would turn into fine ash and be easily absorbed in the glaze."

 

[PeterH]

18 minutes ago, Frenchie Argent said:

The reason for the dry glaze... I am trying a William De Morgan’s technique of applying porcelain slip to bisque tile and then sticking a piece of paper with the colored image (painted in glaze) to the slip with sodium silicate. When I applied the last step using the liquid glaze, it made the paper rewetted and it lifted a little from the slip. So his process put dry glaze, maybe because of the rewetting problem... all the old information never went into details about this... so I can just take my powdered glaze and sprinkle it... ???

Like Min I've always assumed that the he used china paints (or oxides).
https://williammorristile.com/articles/tile_making_process.html

Am I right in believing that De Morgan used a lead glaze, and that these are pretty forgiving (re crawling, pin-holing, etc)? 

@Frenchie Argent What temperature are you intending to fire at?

 

[Frenchie Argent]

I also read that he used overglaze paints(lead China paints),majolica style at first on tin glazed tiles. But he switched to the paper in slip process, and used underglaze paints... so since no one gives technical info in these articles I assume since they said underglaze specifically then they contain frit etc. I was going to fire my test tile at 04 since I’m using a commercial bisque tile. Later if this process works at all I am going to use my own tiles.