Pots took two days to absorb glaze

[Lainer]

Hello. I am new to this forum and I have a two part question. I’ve recently fired greenware and accidentally included a glazed item. Some of the pots stuck together in the kiln. Managed to get them apart all but one.  I wondered if including the glazed piece could have caused this even on those pots not near it  and on a different shelf.  
 

Today I applied glaze to the pots, and the glaze did not absorb and took two days to dry.  This is glaze that I’ve used previously with no trouble, so I’m wondering if something happened in the kiln that could have contributed to this?  Thank you for any help you can offer. 

Edited September 17, 2023 by Lainer
Clarity

[Lainer]

My friend fired the greenware at cone 04. 

Edited September 17, 2023 by Lainer

[Min]

Hi and welcome to the forum!

What cone did you bisque fire to? What type of clay is it, lowfire, midrange or highfire?

[Lainer]

Thank you for your reply and welcome.  My friend actually owns the kiln and I believe bisqued to cone 4.  The clay is stoneware (fired at 5-6).  Like I said we did have have one bisque item already glazed which did stick to a piece of greenware laid on top it. But others items on different shelves stuck together as well. 

[Min]

3 hours ago, Lainer said:

I believe bisqued to cone 4.  The clay is stoneware (fired at 5-6)

If the kiln was fired to cone 4 then for a typical bisque firing this was way too hot. Common bisque cone is 06 - 04.

Common cone numbers go from 022 up through 14. The zero in front of cones 022 up to 01 is very important. There is a big difference between a typical cone 04 bisque and a cone 4. Cone 04 will leave the pots porous enough for glaze to easily stick to it, cone 4 is nearly at the maturity level, this is why the glazed pot fused to the bisque piece that was on top of it. 

It's difficult but not impossible to glaze overfired bisque. Try warming the piece up in the oven then dipping it in the glaze. Brushing glazes go on easier but each coat will take longer to dry. It might be easier to remake the pots rather than try and glaze them.

edit: I wouldn't fire a bisque piece on top of a glazed piece even at cone 04. Some glazes start to flux (melt) enough at cone 04 that they could still stick to a bisque piece.

Edited September 15, 2023 by Min

[oldlady]

lainer,   not a criticism but a suggestion.   the vocabulary used in pottery is very broad.   your definition of  "bisque" may be just a little different from someone else's understanding.   there are a number of terms available in a glossary here in the first section of the forum.

my problem is in your description of a "bisque  item  already glazed."   bisque is a noun, bisqued is a verb.  bisque usually describes a piece that has been fired with no other substance on it.   i am picturing a fired item with some sort of liquid glaze applied to the surface but not yet fired on.   or one that has been fired again with a covering of glaze that remains on the piece so it is finished.

there is also an "EDIT" function located in the 3 little boxes on the top right so you can correct the title.  it is easy.

Edited September 17, 2023 by oldlady
correction

[Lainer]

Thank you for your suggestions. Much appreciated. 

[Bill Kielb]

On 9/15/2023 at 6:51 AM, Lainer said:

Thank you for your reply and welcome.  My friend actually owns the kiln and I believe bisqued to cone 4.  The clay is stoneware (fired at 5-6).  Like I said we did have have one bisque item already glazed which did stick to a piece of greenware laid on top it. But others items on different shelves stuck together as well. 

Not sure this helps but ….

Sounds like your friend errantly bisque fired to cone 4 instead of cone 04  ( we have all done it)

cone 04 = 1063 f  (sintered and absorbent)

cone 4 = 1162 f ( starting to melt - explains why things stuck together elsewhere)

lowfire cone 06 - 04 often used to bisque low, mid and highfire clays leaving the body sintered open and ready for decorating, but a bit sturdier than greenware.

[Babs]

The above advice is sound but unless clay is also v low fired clay, doeant explain the unglazed ware sticking together at cone 4, @Lainer, did they distort also? Bloat?

What is the firing range recommended fir yiur clay?

[Min]

2 hours ago, Babs said:

The above advice is sound but unless clay is also v low fired clay, doeant explain the unglazed ware sticking together at cone 4, @Lainer, did they distort also? Bloat?

 

Agreed. Did the wording change from the original post? I took the first post to mean it was a glazed piece that stuck to bisque. 

[Lainer]

Thank you.  I did change the wording as advised by someone from this forum.  New to pottery making on my own and I’m learning the lingo.  Anyway there was one piece (glazed) included in the firing that we believe was previously fired.   That said quite a few of the pots were stuck together when we took them out of the kiln.   There was no distortion or bloating.  They actually came apart with a slight tap.   My bigger question regards how long it took the glaze to dry.  Two days for one coat.  I tried painting it on and dipping. In fact the first dip didn’t fully absorb but seemed spotty, like it absorbed in some places but not others.  
 

I really appreciate your thoughtful responses.   I had taken several classes before setting up my own little studio.  So much to learn!

[Pres]

Hi all, I have to chuckle a bit over this discussion, as it has never happened to me in the past, because I always used cone packs firing the kiln to the drop of the cones. At school I used sitter with the mini cones then bars. Always kept the cones for glazing on a glaze ware shelf, and kept the cones for bisque on a greenware Unfired ware) shelf. In the last two years, I have noticed several times that I had set the kiln to ^06 for a glaze firing, or ^6 for a bisque as I am now using a kiln controller with a touch screen that uses a scroll of cone numbers. . . if not careful, easy to do. Thank goodness I always double check everything before turning the kiln on or even once again after starting it up.

 

@Lainer, welcome to the forum. You will find that we are a pretty patient group, and happy to be of help. After all, the journey here is long and often has chuckles or hiccups!!

best,

Pres

[Denice]

I have been working with clay for 55 years and I still feel like I have a lot to learn.   You have set up a studio but you still need to take some ceramic classes.   Check out several different ones,  find a teacher that will let you help load and unload  and fire kilns.   When I was getting my degree  we had to make clay for the beginners,  sometimes helped load kilns and definitely unload them.   We are talking about big gas kilns that you could stand in.  Once a week we had to give the main work area a good scrubbing,  one day each semester was grinding and coating kiln shelves day.  You finally get to the level where you make general glaze for the classes.   A master student hands you a drill mixer,  5 gal bucket and formulas and tells you to start mixing.  If you decide to get your masters degree you are suddenly a teacher.  They were short a hand building teacher and tried to talk me into teaching a class even before I got my BA.   You probably won't run into a program like they have at college,  just make sure you find someone that is willing to share their knowledge and not just stick you behind a wheel.   I would find a evening class to take now to meet other potters and share ideas.  I haven't done it lately  I end up helping to teach the class because they don't have enough teachers.   Denice