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Hello!
This may be a question that's a little silly, but I can't seem to find the answer anywhere.

I've taken a liking to brushing on glazes on a banding wheel, as I've used earthenware clay/glazes for the majority of my time making pottery, and just recently decided to try a few different clay bodies and still intend to use brush-ons as much as I can.

My question comes from the level of difficulty brushing 3 coats onto Cone 6 stoneware or porcelain (that has been fired and matured to Cone 6) brings, as It's not porous and takes a while for each coat to fully dry. As I've been looking at some different company glazes/glaze combinations and techniques (specifically Mayco), a lot of them have said to bisque fire to Cone 04, and then glaze fire to Cone 6 and it makes sense to me, but I still can't find it written anywhere definitively that that is the way to go about brushing on stoneware glazes.

Is bisque firing stoneware or cone 6 porcelain to Cone 04 and then glaze firing to 6 a common practice when brushing on glazes or even dipping?
Any information regarding this topic is greatly appreciated or any tips etc. about brush on stoneware glazes are also welcome!

Thank you in advance!!
Caden. :D



 

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Hi Caden and welcome to these forums.

 

Yes, common practice is to bisque to 04 and glaze fire to 6 for a cone 6 clay, be it stoneware or porcelain. 

 

For porcelain that gets really soft and slumpy when firing to maturity then the piece can be supported while firing to top temp then glaze fired with low firing glazes but for studio potters that is not very common at all.

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yes, caden, Min has given you good advice.  bisque to a lower temperature, in your case you mention 04 and then finish with a brushed on glaze that is made to be fired at the temperature that the clay matures to, in your case cone 6.  

 

industry does the opposite to prevent losses.  they fire to maturity and then apply glaze and fire to a lower temperature so brighter colors can be used.  high temperatures usually are too much for bright colors and they burn away leaving a glaze surface with no color.

 

if you want to use brighter colors that can only go to a low temperature, fire your clay to maturity, cone 6 and when ready to apply glaze, heat the fired piece and apply your glaze.  brushing might be hard in this case since the piece will cool quickly and brushing is usually very slow.  re-heat as often as necessary.

 

 bet you only try that once and go to bisque at 04, then glaze at cone 6.

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Thank you both so much!! :D

A question to @oldlady what types of glaze would you use to achieve those brighter colors (referring to temperature)? Are you saying the exact opposite? As in bisque to cone 6 then glaze at 04? Would the risk of crazing etc. be higher when using a cone 04 glaze on a matured cone 6 body?

Thank you again!! :)

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never having done that, i have no suggestions.  all of my info comes from the school of hard knocks.  you need a graduate of a ceramics program who has real knowledge.  maybe someone else will answer with the technical info you seek.

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You can go to the manufacturer's websites  (Amaco, Spectrum, Coyote, Mayco, etc.) and check their color charts for bright colors. I've been experimenting with Amaco's  satin matte series. There are a bright red, orange and chartreuse among others.  They are cone 5-6.

 

Cynthia

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I'm going to piggy-back on this topic with a similar question. What might I expect to happen if I bisque fire cone 6 greenware already glazed with ^6 glaze to ^05 and then do a fire to maturity? I don't do a lot of glazing-mostly I go plain or clear. 

 

I mixed up some glazed greenware before I labeled my shelves and now have no clue which few pieces have a ^6 glaze and which have 05. The glazes in question are commercial with iron-so the "red" of the 6 glaze looks just like the "red" of the 05 underglaze. Most of the load to be bisqued is pieces with underglazes, which I want to fire again with more layers, but the load will also have some of these cone 6 glazed pieces that I can't distinguish. 

 

I know I will discover what does or does not happen by just doing it, but if there is likely to be a visible problem with the cone 6 glazes I'd just as soon know that up front! 

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I brush on glazes a lot. We bisque to cone 06 or 05, apply glaze and then high fire to cone 10. The bisque ware accepts the glazes fine.  hope this helps. Once in awhile I re-fire something that has already gone to cone 10 but needs a touch up. Its always hard to get the glaze to stick and the only way to do so is to warm up the piece so the new glaze will dry.   So choose a bisque temperature below the final maturity level. 06 is pretty common.   rakuku

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I find that brushing a ^6 glaze is like trying to brush icing sugar onto blotting paper.  The brush sticks to the bisque which sucks all moisture out.  Not my favourite pastime.  Bisqueing to a slightly higher temperature, say ^03/02/01 can make the bisque less absorbent making brushing easier.

 

I've also tried adding "brushing medium"/cmc gum/glycerine/...... to ^6 glazes to aid brushing.  Some work with some glazes, some don't.

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Follow up to my post above--there was no visible difference in the bisque results (^05 and ^6 glazes). The 6 glazes look fine & the underglazes as expected. Lesson learned-label my to-be-fired shelves first-too easy to forget what I've!  

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