Glaze and oxides not mixing

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Hello! 

I'm a newbie potter and know very little glaze chemistry but I have spent a year decorating pieces for other potters.

I have been using oxides, wax and etching to decorate glazed pieces but have recently run into issues when using new glazes.

The technique I've been doing -

Starting with a piece that's been dipped or brushed 3 - 5 times with a white glaze I draw on the dried glaze with a pencil, I then wax over the drawing, etch the lines, brush on a dark brown oxide and go over it with wax. In the past the part that is etched will retain the oxide and the wax on wax will get rid of unwanted oxide - creating a clean line drawing.

Recently in using new glazes ( Amaco satin matte and Amaco opaque white ) I am not getting the same results. The glazes used in the past were hand made, they seemed more chalky and dry, these glazes feel more wet (even after days of drying time). The oxides are basically being completely brushed off when I go over it with the wax. It will stick if I don't go over it with wax but not as well as with previous glazes.

Wondering if anyone has any insight about this? I would greatly appreciate it 

[Hulk]

Hi Off!

Good question; am interested to read responses.

My guess would be the commercial brush-on glazes have ingredients that cause that slick surface. Perhaps those experienced in prepared glazes can suggest alternatives.

Thanks for sharing your process. Would you consider posting pics?

[Callie Beller Diesel]

On a side note, I’m not sure why you‘d recoat the lines with wax after you’d added your oxides and wiped off the excess.

I would venture that Hulk is correct. Commercial glazes have binders and gums in them that make them more brushable. Usually if you’re mixing your own, you don’t add those things because it’s a lot faster to dip pieces than to brush. Gums and binders can hold glaze onto the pot, but they also slow down drying. How long are you leaving the oxides on the pot before wiping away the excess? I know of a few people that use the wax Mishima technique you describe with underglazes on green ware. They tend to leave their underglaze washes on for several hours or overnight before wiping.

 

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41 minutes ago, Hulk said:

Hi Off!

Good question; am interested to read responses.

My guess would be the commercial brush-on glazes have ingredients that cause that slick surface. Perhaps those experienced in prepared glazes can suggest alternatives.

Thanks for sharing your process. Would you consider posting pics?

Thank you for your insight! That makes sense. Here's an example of a successful piece.

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45 minutes ago, Callie Beller Diesel said:

On a side note, I’m not sure why you‘d recoat the lines with wax after you’d added your oxides and wiped off the excess.

I would venture that Hulk is correct. Commercial glazes have binders and gums in them that make them more brushable. Usually if you’re mixing your own, you don’t add those things because it’s a lot faster to dip pieces than to brush. Gums and binders can hold glaze onto the pot, but they also slow down drying. How long are you leaving the oxides on the pot before wiping away the excess? I know of a few people that use the wax Mishima technique you describe with underglazes on green ware. They tend to leave their underglaze washes on for several hours or overnight before wiping.

 

The wax gets the excess oxide off best, then I pat the oxide with toilet paper.

Thank you for insight, this is quite helpful. I normally wax / wipe almost immediately and it works perfectly (with the handmade glazes) 

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This is an example of the issue I'm running into.

[neilestrick]

After you etch the lines and go over it with the oxide, just go over the surface with a barely damp dense sponge (like a makeup sponge, or a Xiem finishing sponge). No need for another layer of wax. If the oxides are getting wiped out of the lines, consider using a commercial underglaze instead, as they have binders and hardeners that will keep them in place better.