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Stuck Lids.....


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#1 levoslashx

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Posted 30 January 2014 - 12:30 AM

I recently fired a bevvy of jars for an upcoming show.  I have fired jars before with this clay body and not had a problem, but this time, every lid has stuck.  Every one.  Had I been using even a smidgeon of sense I would have used alumina in the wax.  However, sense was lacking the day I waxed, and now I have a bevvy of useless jars.  I'm wondering if any of you gracious folks have any ideas or tips on how I might loose these lids.  I've tried walloping with a rubber mallet, and whacking with a wooden handle. I've tried heating the seat and lid with a heat gun and torch,  and heating them in an oven 400 degrees then dunking in cold water. All to no avail.  I may be up a creek, but I thought I'd check here first

 

Any ideas would be appreciated.

 

Thanks!

-Levi

 

 



#2 mregecko

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Posted 30 January 2014 - 03:17 AM

Oof... You've covered every trick I know. Were they made with porcelain? I've never known a stoneware to flux that much.

If all else fails... Hit it harder with a mallet?

Another thought might be to use a "bumper" shard of clay (fired) and use a real hammer. The rubber mallet softens the blow and absorbs some of the recoil -- a real hammer has a higher chance of doing damage, but might be just the right amount of force instead?

Sorry to hear about your predicament.

#3 Mark C.

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Posted 30 January 2014 - 03:35 AM

Next time dip your waxed sponge directly into a bowl of alumina Hydrate and then wax the lids dip in powder then wax etc.

As a long time potter the pro tricks are these that is unless the tops are glazed on inside

1st I use a large piece of bamboo about 2 to 2/12 inches round and 14 inches long to use as my tapping hammer-I have used the same one for 30 plus years

a wood handle works best if no bamboo is handy ( I grow all kinds here)

Tap the pot while holding the lid do not strike the thin top edge hit the top near the seat but the solid part of pot

This tapping takes time to learn how not to brake a pot but hit it hard enough to come loose-you tap while turing the part so you tap all around (the rubber is not the right tools as it dampens the blows)

Again hold by the lid tap aronf body near top-be ready for pot lid to separate and fall (so do it near table surface)

Do not heat with torch (you will thermo shock it.

Now if this fails we move to phase 2

This has always come thru for my porcelain pots-I have done more than you can imagine this way

I put them in my chest freezer  for at least 4 hours or overnight.

I fill sink with hot warm water 2/3 full so when the cold pots comes out i can hold it BY the lid and put it under so lid is still dry(cold) and pot is under water almost to lid-they often pop apart-a few time this took a few tries (freezer again till cold-and another hot water dip_

The idea is the cold lid stays cols the pot expands and bingo its free

I have never broken one this way either Daves porcelain  is tough.

Try this and let me know how it works out

Good luck it always works.

Mark


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#4 Mart

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Posted 30 January 2014 - 03:47 AM

Interesting case indeed.

Did you fire it way above allowed temperature?

Glazed the rims by accident?  

Low quality clay that can not take the temperature it supposed to?

That wax you used, burned in to a crap that fused your lids to the pots? (why did yo even add wax?)



#5 Flowergirl3365

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Posted 30 January 2014 - 07:49 AM

Have you tried freezing the jar then tapping the outside around the top with a rubber mallet?  This trick works for me 90% of the time.  The times it doesn't work is when I didn't clean the glaze well enough from the touching surfaces and they glazed together.  

 

Good luck!



#6 ChenowethArts

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Posted 30 January 2014 - 08:20 AM

Honestly, until reading this post I had not heard of lid wax (other than the normal water-based stuff that I use anyway)... but I can attest to the fact that the different techniques described here work.

 

I found this just a while ago and would love to hear of anyone's experience with Marvin Bartel's Hint 4 - colored lid wax.


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#7 TJR

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Posted 30 January 2014 - 08:34 AM

I'm with Mark. If tapping with a wooden handle doesn't work;

Place pots in a freezer overnight. Then run hot water over the body of the pot -lid stays cool. Hand on to the knob, while tapping lightly in a downward motion. Hold pot close to the bottom of the sink or...ooops.

TJR.

Rubber mallet won't work. Too soft. Swearing won't work.. too harsh.

T.



#8 Pres

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Posted 30 January 2014 - 09:20 AM

I used to put pieces in water, and if they would fiil, let them.  Then Icould rap lid harder. If they did not fii, I would know Iwas in trouble, and use freezing.


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#9 levoslashx

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Posted 30 January 2014 - 01:15 PM

Thanks for the ideas.  I'll give the freezing/hot water bath a go this afternoon.

 

It is a porcelain I'm using. I think the problem is that I recently switched kilns.  Where before I was using a kiln sitter, the new kiln is computer controlled.  I think more heat work was done with the new kiln compared to the old, and this caused the fusion of the lids.  Should have done a test firing that wasn't comprised of ALL jars. 

 

Thanks again.

 

-Levi



#10 mregecko

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Posted 30 January 2014 - 01:21 PM

Good luck -- let us know how it works out.



#11 mss

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Posted 30 January 2014 - 01:35 PM

I've had luck with a trick from chemistry (stuck ground glass stoppers):  rest the pot's lid on a wooden surface (pot held horizontally), and hit the lid edge with another piece of wood, e.g., the handle of a hammer.  Start gently and work up to a stronger strike.  You could be lucky; and there's nothing to lose.  The idea is that the wood can absorb some shock, leaving the lid intact.



#12 Norm Stuart

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Posted 30 January 2014 - 02:01 PM

Witness cones indicate our computer controlled kiln always fires exactly one cone too much, regardless of the cone-fire chosen or the speed used.  This appears quite common, but Bartlett techs say they've checked their program and  they have not found an indexing error.

 

It's easy enough to fix by always choosing the next lower cone, but it's certainly odd.

Thanks for the ideas.  I'll give the freezing/hot water bath a go this afternoon.

 

It is a porcelain I'm using. I think the problem is that I recently switched kilns.  Where before I was using a kiln sitter, the new kiln is computer controlled.  I think more heat work was done with the new kiln compared to the old, and this caused the fusion of the lids.  Should have done a test firing that wasn't comprised of ALL jars. 

 

Thanks again.

 

-Levi



#13 levoslashx

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Posted 30 January 2014 - 07:11 PM

Well, one down, nineteen to go!  

 

Got one lid to pop after a few freeze thaw, hot water bucket cycles. I've never been so happy to salvage one pot in my life.   No glaze held it, just sticky bare porcelain.

 

I'll throw some witness cones in there next time to get a a more accurate answer about the heat work.  

 

Onward and upward.

 

-Levi



#14 Karen B

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Posted 30 January 2014 - 08:56 PM

This may be too late, and I hope you had good luck, but a variation on the above tips is to heat the jars, nice and hot, back in the kiln. Have a bunch of ice ready and put some on the lid. It should sizzle a bit, and tap tap with wood and pop, it comes off. Be ready to catch it.



#15 Timseeclay

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Posted 01 February 2014 - 10:43 AM

The glaze used on the inside could be the culprit. If it contains sodium, or other low temp volatiles they will be trapped in the vessel. With the only bear clay available being the areas you waxed they flux out the connection. Alumina wax can help but with one of our studio glazes that contains GB it still does not prevent sticking from fuming. Turns the pots into mini salt kilns it does.



#16 Norm Stuart

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Posted 01 February 2014 - 03:22 PM

I know this is contrary to every advice I've ever heard from potters over the years, but when using a porcelain which gets too vitreous, it's far easier to fire the stoppers separately from the jars, just as if both sides were glazes.  We've not experienced much in the way of stoppers not fitting the jars after they are fired.

 

We had one person who made teapots and what not.  A college instructor had always told him that any piece which belongs on a table should be fired flat on a kiln shelf.  Unfortunately his mentor did not seem to inform him well as to how much glaze to apply, so running the kiln himself his pieces were most frequently were attached to a large excess of glaze which fortunately easily pulled off our alumina hydrate kiln wash, but which would have required extensive grinding to make usable.  This happened three times before he decided he probably wasn't as skilled as his revered teacher and began placing his pieces on ceramic stilts.

 

That's my reaction to people who use kaolin/ silica kiln wash rather than far more refractory and easily detached kaolin/alumina.  Kaolin/silica may be just fine for their work because they don't apply excess glaze -  but very few people at our studio  have that skill, so we need an alumina kiln wash which allows us to simply lift pieces with excess glaze of the shelf with the excess glaze still attached to the offending piece.

 

I suggested the over-glazer use test tiles for each glaze to learn how far different thicknesses of each glaze would travel - but test tiles always seem like too much work to contemplate.  Much better to slather glaze on their actual ware and hope for the best.

 

I recently fired a bevvy of jars for an upcoming show.  I have fired jars before with this clay body and not had a problem, but this time, every lid has stuck.  Every one.  Had I been using even a smidgeon of sense I would have used alumina in the wax.  However, sense was lacking the day I waxed, and now I have a bevvy of useless jars.  I'm wondering if any of you gracious folks have any ideas or tips on how I might loose these lids.  I've tried walloping with a rubber mallet, and whacking with a wooden handle. I've tried heating the seat and lid with a heat gun and torch,  and heating them in an oven 400 degrees then dunking in cold water. All to no avail.  I may be up a creek, but I thought I'd check here first

 

Any ideas would be appreciated.

 

Thanks!

-Levi



#17 levoslashx

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Posted 04 February 2014 - 11:10 PM

Well, as a final update:

 

I found a method on an old clayart thread which suggested spritzing a bit of water into the lid seating, freezing, then hitting with a wooden implement to break the join free.  This proved to be the most efficacious. The freezing, dousing in hot water up to the join method worked as well, but it was cold enough outside here to spritz and freeze most of the jars at the same time it was easier without the bucket of hot water.  I lost six of twenty due to small bits of glaze breaking away, stuck to the lid.  As fate would have it, those six were probably the best, but I'm still grateful for what I have.

 

Norm:  I've thought of firing the lids separately, but it seems that the lid would conform to any contour of the shelf so that when it was placed back on the jar it would wobble.  I have a couple refires that I'll fire this way to check it out. 

 

Your other point is interesting as well.  The using test tiles vs. using actual ware debate.  It all boils down to impatience, I think.  A person has an idea, and they want to see the idea come to fruition. So they cut the test tile step, or they fire an entire load of jars without testing the new kiln first.   But after a person has been burned enough, or loses enough money from their mistakes, they learn to slow down a bit, and test.....hopefully.



#18 neilestrick

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Posted 04 February 2014 - 11:59 PM

A little alumina on the lid seating will solve all your problems. Just mix it in your wax resist. The only way to ensure that a lid fits perfectly is to fire it on the piece. While much of the time you could get away with firing them separately, those times that they warp will inevitably be on the most important pieces. My concern would not be with the lid warping, but rather with the lip of the pot warping. If the lid fits the way it should, it would only take the slightest movement to screw up the fit.
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#19 Benzine

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Posted 05 February 2014 - 03:01 PM

A little alumina on the lid seating will solve all your problems. Just mix it in your wax resist. The only way to ensure that a lid fits perfectly is to fire it on the piece. While much of the time you could get away with firing them separately, those times that they warp will inevitably be on the most important pieces. My concern would not be with the lid warping, but rather with the lip of the pot warping. If the lid fits the way it should, it would only take the slightest movement to screw up the fit.

 

You just take the vessels with the non-fitting lids, and sell them as conceptual pieces.  The lid and vessel, two things that were made to be together, don't fit.  I mean really, how many of us out there, really "fit" with anyone else maaaan?.....


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#20 Babs

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Posted 05 February 2014 - 07:18 PM

 

A little alumina on the lid seating will solve all your problems. Just mix it in your wax resist. The only way to ensure that a lid fits perfectly is to fire it on the piece. While much of the time you could get away with firing them separately, those times that they warp will inevitably be on the most important pieces. My concern would not be with the lid warping, but rather with the lip of the pot warping. If the lid fits the way it should, it would only take the slightest movement to screw up the fit.

 

You just take the vessels with the non-fitting lids, and sell them as conceptual pieces.  The lid and vessel, two things that were made to be together, don't fit.  I mean really, how many of us out there, really "fit" with anyone else maaaan?.....

 

Way too deep for this forum, Socrates! I fit, it is all the rest of you who are the problem. :)  






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