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underglazes/lowfire/cracking

updated mon 16 may 05

 

Elizabeth Priddy on thu 12 may 05


I think it works best when the iece is bisqued or when it is just barely leather hard.
A true coat of color is best applied to bisque so that you can see the coverage or lack of it.
If you do it on wet clay or leather it tends to be streaky.

For some colors, it is best to bisque it again before applying the clear glaze on top as the unfired velvets have some stuff that can opacify or make the clear go matt.

The brightest clearest strategy I have found is to apply a white slip to the leather hard piece and fire it. Then apply your color and either refire or go ahead with a coat of clear and fire.
If it matts the clear, you can just apply another coat and fire it again.

Don't go by the work on my site to see this, though, as that is all cone 6 stoneware and another technique altogether. I use this for work with students who like to paint but who
are not interested in chinese brush style.

E

Jonathan Kirkendall wrote:
Question to those who work with lowfire clay - when is the optimum time
to add underglazes to earthenware work? After years of working at
stoneware temps, I'm having fun experimenting with cone 04 earthenware -
well, fun, until I add the underglaze colors using Velvet underglazes
and ended up cracking all the rims...a full week's work of manipulating
forms and experimenting and nothing working. Grrrrr. I've been
painting the underglazes on when the piece (bowl form, but ovaled and
trimmed) at leather hard, and right about the time I think to myself
"Ah, how pleasing!" I notice cracks in the rim.

Should I bisque the work first then add underglazes?

Beginner's mind...

Jonathan in DC

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Elizabeth Priddy

252-504-2622
1273 Hwy 101
Beaufort, NC 28516
http://www.elizabethpriddy.com

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Jonathan Kirkendall on thu 12 may 05


Question to those who work with lowfire clay - when is the optimum time
to add underglazes to earthenware work? After years of working at
stoneware temps, I'm having fun experimenting with cone 04 earthenware -
well, fun, until I add the underglaze colors using Velvet underglazes
and ended up cracking all the rims...a full week's work of manipulating
forms and experimenting and nothing working. Grrrrr. I've been
painting the underglazes on when the piece (bowl form, but ovaled and
trimmed) at leather hard, and right about the time I think to myself
"Ah, how pleasing!" I notice cracks in the rim.

Should I bisque the work first then add underglazes?

Beginner's mind...

Jonathan in DC

Eleanora Eden on sat 14 may 05


I work all the time with velvets and other underglazes on either dry
or bisc pots and they both work equally well. When it comes to EZ
strokes I think that coverage is more even on dry clay than bisc but
you don't mention those.

Assuming that the rims of your bowls would have been fine without the
added velvets.....you are saying the velvet cracked off the rim, or
the rim of the pot cracked?

Eleanora




>Question to those who work with lowfire clay - when is the optimum time
>to add underglazes to earthenware work? After years of working at
>stoneware temps, I'm having fun experimenting with cone 04 earthenware -
>well, fun, until I add the underglaze colors using Velvet underglazes
>and ended up cracking all the rims...a full week's work of manipulating
>forms and experimenting and nothing working. Grrrrr. I've been
>painting the underglazes on when the piece (bowl form, but ovaled and
>trimmed) at leather hard, and right about the time I think to myself
>"Ah, how pleasing!" I notice cracks in the rim.
>
>Should I bisque the work first then add underglazes?
>
>Beginner's mind...
>
>Jonathan in DC
>
>______________________________________________________________________________
>Send postings to clayart@lsv.ceramics.org
>
>You may look at the archives for the list or change your subscription
>settings from http://www.ceramics.org/clayart/
>
>Moderator of the list is Mel Jacobson who may be reached at
>melpots@pclink.com.

bonnie staffel on sun 15 may 05


My thoughts about your rims cracking is that you have added the wet
underglazes to the bottom area first and in the meantime the rims are
getting dryer unevenly. I have found (outside of faulty clay) that most
cracking problems are from the drying process. Perhaps you could wrap the
outside of your pot rim with plastic while you are working in the lower
areas. Spritzing it occasionally may also help in retarding the drying
process. I would then cover the entire piece so the moisture can even out.

Regards,

Bonnie Staffel
http://webpages.charter.net/bstaffel/
http://vasefinder.com/bstaffelgallery1.html
Charter Member Potters Council