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Beachbumz Tikis, Troffs, Shots and Tings From Maui - Couple new one's I finally finished. |
Beachbumz
Grand Member (first year) 
Joined: Jan 09, 2008
Posts: 991
From: 21°/156° MAUI
|  Posted: 2011-03-25 11:53 pm Permalink
Quote:
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On 2011-03-21 20:01, TikiKIrby wrote:
Cool details and finish on the Tonga mugs (on top of the great sculpt!).. Also very cool to donate to the relief fund..
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Thanks TikiKIrby, I'm learning every time. I was able to raise $87.00 for the relief fund thanks to an ebay bidder, so I'm happy about that.
Unfortunaly I pulled three mugs out of the kiln this morning and one I made for another TC'r cracked as it was cooling.. Bummer.. Oh well I was on a roll for awhile another going on the wall of cracked mugs..
These two guys were okay though..
Aloha
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Check Out Da Website...www.beachbumz.com
[ This Message was edited by: beachbumz 2011-07-16 19:32 ]
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MauiTiki
Tiki Socialite
Joined: Jan 20, 2003
Posts: 680
From: A rock in the middle of the Ocean
| Posted: 2011-03-28 9:30 pm Permalink
I don't get it, why would it crack hours after coming out of the kiln?
Is the crack directly along the seam from the mold?
Maybe try pour them a little thicker.
Stop by I have a bucket of slip for you.
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MauiTiki
Tiki and flower pattern Stickers www.stuckonmaui.com
Maui Tiki Tours & Tiki Mugs www.mauitikitours.com
Hippie Stickers www.hippiestickers.com
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GROG
Grand Member (first year)
Joined: Jun 21, 2006
Posts: 6180
From: Tujunga
| Posted: 2011-03-29 12:56 am Permalink
Don't open the kiln until it's cooled down. GROG let GROG kiln cool until it's warm to the touch, then GROG slightly crack lid and let kiln cool down completely. If GROG fire early enough in the day and let kiln cool down overnight, everything is cooled down completely by the time GROG open it the next day.
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GROG miss Tiki-Kate
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danlovestikis
Grand Member (8 years) 
Joined: Jun 17, 2002
Posts: 3565 | Posted: 2011-04-12 08:52 am Permalink
All the books I've read on the firing process say let the kiln cool until the temperature is 130 or less. You should be able to hold the mug in your hand comfortably at that temperature. I'm with Grog I have let the kiln cool 24 hours after it fires and I've never had anything crack. I have had explosions due to air bubbles but that is a whole other problem.
Hey I'm so bummed that I didn't win your two tiki bowl on eBay. Congratulations on a good auction. Will you have more bowls going on there? I need to win one before May 27th. I think MauiTiki has one he is making for me. I need one from each of you, Wendy
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Beachbumz
Grand Member (first year)
Joined: Jan 09, 2008
Posts: 991
From: 21°/156° MAUI
| Posted: 2011-04-12 8:25 pm Permalink
This mug was room temp by the time Rob and I took them out of the kiln. I heard it "pinging" a few times afterwards but when I returned home after work I found it cracked.. I think it was the slip possibly used for that batch, it was extra thin, possibly the cause.. Oh well, fun learning..
I'm going to try and get a few more Troffs started this coming week, starting to slow down at work so hopefully.. Once the kidz go to sleep daddy plays with the clay..
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Beach Bumz Maui
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danlovestikis
Grand Member (8 years)
Joined: Jun 17, 2002
Posts: 3565 | Posted: 2011-04-12 8:29 pm Permalink
We finally won a super expensive mug on eBay. Weeks later we were standing in the tiki hut where he has hundreds of mugs and we heard a ping. We looked at each other and said Nawww not that mug, pulled it off the shelf and sure enough a long hairline. Sometimes it's just the change from and air conditioner or heater vent reaching the mug. Slip I don't know about that. I hope it never happens to you again. Playing with clay is very relaxing, good night, Wendy
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ebtiki
Grand Member (first year)
Joined: Feb 08, 2009
Posts: 227 | Posted: 2011-04-13 12:31 pm Permalink
I've had this happen, too - always with mugs at room temperature. I've been wondering if it's related to washing mugs (which I do), is some are porous enough that they absorb water in the process.
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ebtiki / eab21 on Ooga-Mooga
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Babalu
Grand Member (5 years) 
Joined: Nov 19, 2006
Posts: 2498
From: Lemon Grove
| Posted: 2011-04-14 12:25 am Permalink
Hey guys,
I've had this happen before too. Glaze will continue to cure long after it has been fired. Dunting could be the cause when you see long vertical cracks like this. I have seen where this will happen when there is a thicker layer of glaze on the bottom inside of the mug than are on the inside walls. Anyway the below is a short explanation that I pulled off of the Internet:
Dunting
This is a special type of crack which occurs from stresses caused during firing and cooling.
This stress primarily occurs during two critical points of firing called silica inversions which occur at 1063¢ª F or 573¢ª C and 439¢ª F or 226¢ª C.
At these inversion points, the structure of the silica molecules rearranges.
It is important to fire slowly through these two temperatures and electronic kiln profiles often do this for you automatically while they are heating.
Most dunting however is caused during cooling.
These cracks appear as long, clean, body cracks with sharp edges.
If the pottery or ceramic is glazed, the glaze edges are sharp.
They can be vertical, horizontal or spiral.
There are three main reasons why cooling dunts occur.
The first occurs as you cool through the first silica inversion at 1063¢ª F.
At this inversion the body contracts suddenly.
The more silica, quartz, in the body, the more contraction.
Since different parts of the pottery or ceramic reach this temperature at different times, it doesn't all contract together and that causes stress which can crack.
Take for example a tall pot.
The top will cool much faster than the bottom, because the bottom has the whole temperature of the kiln shelf keeping it warm.
The top will cool faster than the bottom, causing a crack around the bottom wall.
The second occurs as you cool through the 439¢ª F inversion.
A similar thing happens as above.
But, pottery and ceramic artists sometimes like to open their kilns at about this temperature to see their pieces and this will make it much worse.
The third type of cooling dunt occurs months or even years after firing.
Sometimes the pottery or ceramic might split right in half after three months.
This is usually the result of thermal shock.
In this case the clay and glaze expand at different rates when exposed to temperature variations and this change causes the object to crack.
To be more specific, the body contracts more than the glaze.
If the glaze is weaker it will shiver.
If the clay is weaker the object will crack.
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MadDogMike
Grand Member (3 years) 
Joined: Mar 30, 2008
Posts: 6403
From: The Anvil of the Sun
| Posted: 2011-04-14 1:24 pm Permalink
Babalu, thanks for the info and the new vocabulary word
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Beachbumz
Grand Member (first year)
Joined: Jan 09, 2008
Posts: 991
From: 21°/156° MAUI
| Posted: 2011-04-14 2:57 pm Permalink
"These cracks appear as long, clean, body cracks with sharp edges.
If the pottery or ceramic is glazed, the glaze edges are sharp."
Mahalo's for that info Babalu, That sounds like it.. The bottom of my mug is much thicker than the sidewalls, I think I'll let them get a little thicker and make sure to drain the slip all out from the bottom better, that may be my problem.. I think the firing and cooling process is alright because it only seems to be happening to a few of my mugs, my friends mugs that I fire with are usually okay..
Wendy look what I've been making.. Finally got around tho making a better mold for the Troff's legs, hopefully I'll have a couple done this week and ready to fire..
Tongo asked me to make him some hands so he could release his inner Shaka, not done yet but there coming together..
Aloha
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ebtiki
Grand Member (first year)
Joined: Feb 08, 2009
Posts: 227 | Posted: 2011-04-14 9:21 pm Permalink
Thanks, Babs - although my head hurts now!
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Beachbumz
Grand Member (first year)
Joined: Jan 09, 2008
Posts: 991
From: 21°/156° MAUI
| Posted: 2011-05-01 7:17 pm Permalink
New Jungle Brown glazed Tongo, Mahalo Rob!
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danlovestikis
Grand Member (8 years)
Joined: Jun 17, 2002
Posts: 3565 | Posted: 2011-05-05 10:17 pm Permalink
My bowl! Thank you, Wendy
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Beachbumz
Grand Member (first year)
Joined: Jan 09, 2008
Posts: 991
From: 21°/156° MAUI
| Posted: 2011-05-06 12:03 am Permalink
Wendy I would never forget you!!! Your Troff-Bowl is hopefully sitting at my friends house were Rob and I fire our mugs. As soon as he gets back from his trip It's getting some color put on.. Here's a sneak peak before it got fired..
And Two other guys waiting for fire as well patiently......
[ This Message was edited by: Beachbumz 2011-05-06 00:04 ]
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danlovestikis
Grand Member (8 years)
Joined: Jun 17, 2002
Posts: 3565 | Posted: 2011-05-08 08:52 am Permalink
Super beautiful already! Your mug has shipped I'm PMing your tracking number. Thank you so much, Wendy
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