"glazing Pots With Lids" 101, Please

[Isculpt]

I accidentally posted my question to "Clay & Glaze Technical", but no joy there. You folks, however, always help me out of the jams I get myself into. So...

I've been following the post regarding lids stuck to pots by glaze, and it has raised some basic questions for me. I make sculptures, paint them with underglazes and fire them to cone 06. No sticking glaze issues because I only use underglazes. But I was invited to enter two sculptural teapots in a teapot show, and I suddenly find myself with glaze issues! I have bisqued the "pots", underglaze fired them (both firings at 06), and now it's time to add a clear satin cone 5 glaze. I had assumed that the lid and pot would be fired separate from each other, but after reading the post, it looks like that's not the way it's done (perhaps because they need to stay together to avoid warping differently from each other?). If I'm understanding this correctly, and I am supposed to fire them together, what is the secret to keeping them from sticking? Does it all come down to waxing? (Do multiple coats of water based wax help?) And do I have to worry about the glaze melting and running past the waxed area into the well where the lid and pot fit together? For that matter, since the two sculpture "pots" don't have a foot like typical functional ware, how far up the side of the pot must I wax to avoid glaze running down and sticking the sculpture to the shelf?

 

All of this leads me to what may be obvious to a functional potter, but seems like a stumbling block to me: I would rather that the pots be completely glazed around the neck openings, but if I have to fire the pots with their lids in place, it seems that it isn't possible. Today is glaze firing day, so any help will be appreciated!

[Isculpt]

Okay, part 2 of Glazing Pots with Lids 101 : I have just noticed fine cracks that developed in the last firing. Arrrrgh!!! Should I just call these babies "non functional" and forget the cone 5 glaze firing? Will glaze seal the fine cracks or is the higher temp likely to cause even more cracks? I can always cop out and use an acrylic top coat on the "decorative" teapots, saving myself all sorts of anguish and stress, but I REALLY wanted them to be functional....

[Chris Campbell]

You might have to settle for their function being eye candy.

Those cracks aren't going away.

 

For future reference many potters wax between the lid and the mouth of the pot.

No glaze on any surface that might run downhill into it.

No glaze about one half inch from the bottom ... for most glazes properly applied.

Your commercial clear glazes tend to stay where they are put.

 

I am also going to recommend one of the best pottery handbooks around.

Clay, a studio handbook by Vince Pitelka.

My bible!

[Idaho Potter]

As usual, Chris, you are right on. I just found out yesterday that Vince Pitelka's book CLAY: A Studio Handbook has been pulled from production. No one seemed to know if it's because it's being updated or revised, but it saddens me that it might not be available any longer. What a loss!

[Madison Mitchell]

I have never been one to follow the rules in potting. I do what *I* want to do, "right" or "wrong", and I see how it turns out.

So I fire my pieces and lids separately. I like glaze on the gallery, so I have glazed the whole piece, and just waxed the lid, and fired it next to the piece it is supposed to fit on. So far, so good, I haven't had any issues with warping, especially if the lid is smaller.

I actually hate the unglazed edge of the rim also, so at one point, I was using wadding, normally used for soda firing, to "stilt" my lids. I did this by making a cone of the wadding, wide enough to support the lid, and then used Elmers to attach the lid to the top of the cone, only touching it in the center of the lids underside. When it was finished, it looked kind of like a toadstool or mushroom. It worked well, sometimes the lid would come off the wadding of it's own accord, most times I was able to break it off cleanly. Then, the only unglazed part of the lid was a little circle, in the center of the underside of the rim, which I preferred to the unglazed edge.

I know it's a little late in the day for this idea, and may not be an option for you, but it might come in handy in the future.

[Chris Campbell]

I'm going to write Vince and find out for sure.

 

It would be a huge loss to the knowledge base of basic pottery skills.

Will let you know what I hear.

[terraforma]

Here's what the instructor in my studio always recommends: 1) firing lids on the pot; 2) alumina wax on the lid and gallery both to resist glaze and to keep lid and pot from sticking together bare clay to bare clay; and 3) knowing the glaze well enough to understand how much it may or may not run - glaze the lid and pot and lid to allow for that movement (same advice for the foot). Not an exact science.

 

I too like the idea of having a glazed gallery and lid as Madison Mitchell describes, and may try it myself someday, but it seems to me that a lid is less likely to slide and fall off when pouring if the lid and gallery have that bit of clay-to-clay friction.

 

Good luck!

[Mossyrock]

I just purchased Vince's book from eBay for $15, brand new, including shipping.......what good luck!

[Marcia Selsor]

Vince's book is being revised.

I add a little alumina hydrate to the wax I use on lids. This helps avaoid fusion with high flux clay bodies. I take some Atoofsa wax and add heaping teaspoon into about 5 fl oz. and shake well. I lable it w/ AL and store it. It keeps as well as the unaltered wax. The alumnia can be washed away after the firing. I use this on all my porcelain...feet and lids just because the clay can fuse to shelves when fired hot.

 

Marcia

[Isculpt]

Thank you all. I've learned a lot from your answers. And Chris is right: these teapots' function is going to have to be as eye candy. Meanwhile, I've attached images of the two NON-functional teapots. Now I'm off to find the Clay book recommended by Chris so that maybe next time my teapots will be functional!

[Chris Campbell]

The teapots are wonderful ... I don't think you have to worry about someone using them every day at breakfast!

Eye Candy for sure.

 

Vince's book is available through the Potters Council site and if you are a Member you would get your discount.

 

http://ceramicartsdaily.org/bookstore/best-sellers/clay-a-studio-handbook/

[jacqui sos]

A little bit off the topic - but if someone could help I would certainly appreciate it...Ive been making French Butter Dishes (I think theyre known as "Butter Bells" in the U.S.) and having a lot of trouble with the Cone 6 glaze firing. If I fire the lid and the pot separately, they both warp. If I fire them together, they usually stick despite using wax with alumina in it. Ive also tried making sacrificial "saucers" to sit both the bell and the insert on - but had trouble with the clay fusing to the pot - although I do concede it could have been that particular clay (which Ive subsequently heard doesnt fire to the temp on the pack!). Anyway - if someone out there in Clayland has a solution, I'd be grateful! Here's a pic of one that worked!!

[Sputty]

.

[Callie Beller Diesel]

I know Min swears by putting the insert on a waster to keep it from warping. Try making one out of different clay if that one didn't work.

I fire mine together, and I find even if you use alumina wax, you have to really do a last wipe on the parts that will connect with clean water and sponge, to get rid of residual glaze dust. Also, placing things in the kiln is important: if the lid has even a slight amount of play, it can slide to one side or the other, and accidentally contact a glazed part. 

[Min]

For regular old school style butter dishes where the butter sits on the plate I do fire the top dome part on a waster like Callie said but fire the pieces together for the French or crock style butter keepers. Agree that your current clay is probably being fired too high for the pieces to fuse when using alumina hydrate in the wax.

If anyone is interested in making them there is a good article here from Sumi Von Dassow. Like her I make mine from clay that vitrifies for the same reasons she does. 

One of mine

 

[Mark C.]

I make and sell this form but the hundreds. I use cone 10 porcelain fired to cone 10. They will fuze together unless you use hydrate . I dip my wax sponge in a bowl of hydrate (not mixed in wax) I have had zero issues with sticking.Try the dip your wax sponge into some alumina-works for me.Mine are like Mins above with more color but same shapes.Fire them together so they will fit together.

[Sputty]

.

[Pres]

Firing lids of with special needs is often a problem. One of the easiest solutions I have found for French Butter dishes is to fire the lid upside down with a small rim of unglazed area at the top of the pot, and a rim of unglazed area around the circumference of the lid. This allows both to be fired, and everything glazed. 

This same trick works with the Honey Jars that I make where the lid with handle and stem are fired upside down on the pot using the same technique. The problem with the honey jar, that was problematic was is the stem glaze ran any, it would seal the lid where the honey dipper came close to the floor of the honey pot.

 

 

[jacqui sos]

Thanks so much for all your replies. It was so nice to wake up on Christmas morning and read them!! However, I'm hoping you can enlighten me further.... I understand the whole earthenware/stoneware thing - and was actually thinking of making the butter bell out of earthenware because I guessed the shape was not conducive to higher firing in stoneware - I didnt even think about the vitrification "problem".  I'll definitely give it a try next time Ive got some terracotta.

In the meantime - can someone explain the "sacrificial slab" to me? Is it just a "saucer" type thing you put underneath the piece in the kiln? I guess it should be made out of the same clay as the piece? Should it be bisque fired or is it green? Can you use it again after the glaze firing or has it done its job of shrinking and wont shrink any more? Do you only use it for the lid part - and why does that warp more than the pot part?  If it is only for the lid, you would still have the problem (minor I concede) of having the rim unglazed assuming you put it on the slab resting on the rim. Phew...!  Merry Christmas from Down Under!

[oldlady]

jacqui, sumi's directions about the sacrificial slab tell you your answers,  just read it again, slowly.  there is a lot to understand there and sometimes a second or third reading makes the difference.

[Min]

@Sputty, always interesting to hear how others make things. Primary reason for me in making this style of butter dish is the use of the water to seal the air from the butter which keeps it fresh longer, not cooling. I make a couple hundred of these a year, they work. We don’t have the extremely hot weather you are speaking of but could do with a little of it right about now. 

[Sputty]

.

[neilestrick]

I make butter bells from vitrified porcelain, and fire the two pieces separately because I hate the look of the un-fired ring at the top of the inner part on that particular form. I also find that I can get the fit tighter if I fire them separately. I fire the inner part on a very thin waster slab, only 1/16" thick. Any form with an open bottom needs to be fired on a waster slab to prevent it from warping. I have also found that I do not need to bisque fire the slab, and if it warps a little and cracks as I set the crock on it, it still works.

[Mark C.]

Neil are your inners dry(no glaze) at the bottom on the inners or is the top of lid on inners unglazed?

[neilestrick]

12 hours ago, Mark C. said:

Neil are your inners dry(no glaze) at the bottom on the inners or is the top of lid on inners unglazed?

Dry ring at the very bottom where it sits on the waster slab. I find that less offensive than the big unglazed area under the lip where the glaze just has to stop for no good design reason.