Underglaze decoration technic question

[kevinpleong]

I work at a high fire studio and was wondering if anyone had any techniques on how to make a under glaze wash so you can still see the texture underneath?

[Babs]

A wash can be made with just water and oxide, e.g. iron oxide, cobalt oxide or black copper oxide.

Some people apply to green ware and scrape or sand back prebisque. This means there is a dust hazard so appropriate protection required. Some texture may be lost in process depending on depth of texture.

I have collected the dust from this process and used as slip on greenware.

The other is to apply to bisque ware and wipe off with damp sponge. Some of wash penetrates the porous clay body and  thus change the colour of wiped areas.

I have used commercial underglazes, thinned a little and used as above.

[kevinpleong]

I understand how to make an oxide wash using water and oxide. I have a bunch made up. I have a rolling pin that I have been using to roll out some cherry blossom mugs. Unfortunately I want to use pink as the color and at cone 10 it usually burns out... I believe that many under-glazes are formulated so they don't burn out. I bought the pink Speedball under glaze which is rated to cone 10. I want to be able to paint the under glaze on my piece and be able to see the texture.

Edited December 5, 2022 by kevinpleong

[Babs]

I guess you'll have to test a piece. You want an overall cover, not just in the depths of the texture? 

Reds and pink tend to burn out but if rated to c10, test a piece.

Not familiar with the products you are using, may be sensitive to the glaze you are putting over it..

[Pres]

If I were doing what you want to do, I would consider spraying the underglaze on from and angle so that it would pick up and edge of the texture leaving a bare area on the other edge. I have used this technique with 1, 2 and 3 colors from different directions to accent a texture.

 

best,

Pres

[neilestrick]

You can treat the underglaze like any other oxide wash. Water it down as needed. To show texture well, brush it over the entire area, then sponge it off the high points so it stays in the recesses.

[Roberta12]

21 minutes ago, neilestrick said:

You can treat the underglaze like any other oxide wash. Water it down as needed. To show texture well, brush it over the entire area, then sponge it off the high points so it stays in the recesses.

@neilestrick have you taken the speedball pink above cone 6?  I have had maroon and pink burn out at cone 6.  Amaco Red seems to tolerate higher temps, but I haven't tried it at 10.

[kswan]

The problem with underglaze showing texture is that it is usually opaque and hides texture. You can wipe away high points like Neil said, but the filled in spots will not have fine details, if that's what you're going for.  If you want to see fine details, a better option might be clear glaze mixed with a mason stain brushed on in the blossoms. For a more blocky or stylized look, wiping away underglaze from highlights will work.

Maybe even try to mix the underglaze with clear and brush that on? Not sure if it would be concentrated enough color.

Edited December 6, 2022 by kswan
adding more

[Rae Reich]

Be sure to check with Speedball about compatible clear glazes. I have had good results from mixing commercial stains and underglazes with the clear overglaze, but pinks are the most fugitive and temperamental, especially at cone 10 (oxidation, I presume).

Test, test, test!

[kevinpleong]

Thank you. That is a concern which is why I also bought the coral velvet underglaze and I purchased the pink speedball underglaze. Both say they go to cone 10 and the there is a cone 10 test tile image on the website so I’m hoping one of them will work. Thanks for the help. 

[Callie Beller Diesel]

Pink underglazes and stains that withstand cone 10 temperatures can often be killed by reduction atmospheres. You might have to play around with some chrome/tin combinations if the underglazes you’ve chosen don’t work. I couldn’t tell what mechanism is making either of the UG’s you mention pink, as the SDS sheets are too vague. 

[neilestrick]

On 12/5/2022 at 7:31 PM, Roberta12 said:

@neilestrick have you taken the speedball pink above cone 6?  I have had maroon and pink burn out at cone 6.  Amaco Red seems to tolerate higher temps, but I haven't tried it at 10.

I use Speedball pink at cone 6 all the time. I don't love the color, though- too salmon for me- so I cut it 50/50 with white to get a nice soft pink. Could be your clear glaze causing the burnout, or maybe not putting the pink on thick enough.

[Roberta12]

On 12/7/2022 at 10:40 AM, neilestrick said:

I use Speedball pink at cone 6 all the time. I don't love the color, though- too salmon for me- so I cut it 50/50 with white to get a nice soft pink. Could be your clear glaze causing the burnout, or maybe not putting the pink on thick enough.

I actually talked to the Amaco and Duncan people and they sort of shrugged and said, well, yeah, that does happen.    I was just "gifted" some speedball pink.  I will try that!