Tuesday, February 24, 2009

On Second Thought...

As an afterthought regarding my last post, I'm thinking one of the main reasons I started this blog was to share with others how I do things as a way for us to help each other work through problems with our art. So I'll tell what I've read so far on how to do the simple, at-home test, for ceramic durability, suggested by other potters.

But 1st(to CMA) a small disclaimer:

The following information is NOT instructions and should not be interpreted as such - I, in no way will be responsible for injury to anyone due to their following of my tips, ideas, steps, or any other information regarding the way that I performed, or will perform tests, or anything else, on my pottery or art. It is the responsibility of the reader/viewer/commenter of this information to use his/her own judgment, and do his/her own research on the testing of ceramics for durability, or performing any other procedure discussed on this site prior to doing his or her own testing.

Safety Tip: I would suggest wearing a long-sleeve shirt, hand mitten potholders, and safety glasses when performing these tests.

So far, I've performed the boiling/plunging test, whereby I:

  1. Placed my liner test tiles in a zip-lock bag, placed them in the freezer for up to 24 hours (it's suggested to freeze for 24 hrs., but I don't think I froze my tiles every time for this long.

  2. Then I carefully emptied them from the bag into a large pan (I used a dutch oven/a large sauce pan with handles on the sides) with just enough boiling water to cover the tiles. Moved them around with a spoon to make sure they were all covered in the water, then removed the pan the heating element on my cook-top (electric oven) and left the tiles alone to cool for a few minutes. I was attempting to simulate, as closely as possible, the action of one pouring a boiling liquid into a cup - once the liquid is in the cup, it would stop boiling and begin cooling.

  3. I removed the tiles, using a slotted spoon, from the water and placed them on a towel to dry. After they were completely cooled, I checked each tile for crazing (small hairline cracks in the glaze which has a 'tiled' pattern to it), under a magnified light that I have in my studio. If your glaze is white like many of mine are, these cracks are sometimes very hard to see with the naked eye. See other ways for checking for craze lines below.

  4. I repeated this freezing/plunging process 2 more times for a total of 3 times, which is suggested, and so far, none of the pieces have crazed. Now through my reading up on this, I understand that crazing can still take place, anywhere from a few days to months later. In other words, there's no guarantees when performing these types of 'home tests'.

Another way I discovered by accident to check for crazing is to dab some of the water from my 'throwing bucket' (stirred a little to kick up the silica from its bottom) onto the surface of a pot or tile. If the piece is crazed, the water will evaporate or seep into the cracks leaving the silica behind in the cracks, forming a pattern which is easy to see with the naked eye. Other potters' suggestions involve using water-soluble pens (use a color that will show up on your piece) to mark the surface which will show the crazed pattern, but I don't like the idea of messing up my test tiles using any kind of ink because I'm sure, even though it's water-soluble, once it's in the cracks, it would be hard to remove, as it is sunken into the clay body, which is exposed via these cracks. Another suggestion is to use a cheap microscope for viewing. Ron Roy suggested at a workshop that Radio Shack had (note, it's been several years since I attended that workshop) one at a reasonable price.

So that's how I did my first test for crazing. I'm sure it would have been better to perform this test using cups instead of tiles, but I just wanted to get an idea of how stable these glazes are before making larger batches of them and also, I didn't have enough cups to test and was anxious to go ahead and start testing.

I do however, plan to use cups for the second test, which involves heating in the oven, then 'quenching' in room temperature water. As you can see, this must be done with caution also, as anything can happen. Talk about thermal shock! What I've read so far (again, I'd suggest that you read up on this yourself, as I could be wrong in my interpretation of this information) involves placing the cup to be tested in the oven, beginning at 250 degrs. F. and 'progressing' up to 300 degrs. F. and staying at that temp. for 30 minutes. Here is where I'm not sure how fast one should raise the temp. From what I've read, it seems it should be done slowly, but how slowly? Let the oven come up to 300 degrs. F. at it's default rate? That would be pretty fast. This inquiring mind wants to know, if you do, please leave a comment, or let me know via e-mail!

Anyway, the cup(s) is heated at 300 degrs. F. for 30 minutes, then removed (I'll wear hand mittens and safety glasses for this test!) from the oven and placed into room temperature water (it's suggested to do this step in the sink for obvious safety reasons).

This is a harsh test and one that should be done with caution, as anything can happen, which I explained in my last post. I plan to try to use my studio sink for this, as it's a deep janitorial-type fiberglass sink. First, I'll place the dutch-oven I used for my test with the tiles in the bottom of this sink, fill it with enough water to cover the cup, and give it plenty of time to reach room temp. before heating the cup (I assume this is important, as too cold (yikes!) or too warm would not give an accurate result).

I've read (NOT from the ASTM site) that the ASTM says that a piece that passes this second test 3 times should be considered stable enough for 'normal' (to some, 'normal' may be what I or others would consider 'abnormal') use. As I mentioned in my last post, I never could find on ASTM's site where they explain this test and how to do it. It looked to me like they are wanting to charge a fee for their information, but maybe I was not doing a good enough search for the ASTM C 554-93 test. Now I have read enough to know that they are NOT talking about using these pots for 'flame ware' or on the cook-top. This is the industry-level stuff you see in department stores and even most of those ceramics are not made nor intended for cook-top or even oven use. I'm also, not particularly interested in making 'ovenproof' pots, as I understand one should use a stoneware clay which is specifically formulated for ovenware use. But I guess this second test would, if my pot passed the tests, make those pieces 'ovenproof' wouldn't it? I'm just not into making casseroles, etc. at this time, but who knows, I could certainly change course at any time! I'm just mainly interested in my functional ware being microwaveable (yet another test to be performed) and have a good 'clay/glaze fit', hence the thermal shock tests. Later...

Sunday, February 22, 2009

Testing, Throwing, Painting

I've spent the past few days throwing a few cups in order to test my liner glazes. If you're interested in 'how' to test your funtional ware for stability, I would suggest going over to Clayart's potters.org forum or Masteringglazes.com for the detailed how-to's. I have completed the 'freezing/plunging in boiling water' method and so-far-so-good - no crazing!

A word of caution - Be careful when doing any type of 'shock' testing on your ware. Any number of things can happen i.e. popping, shivering (when sharp slivers of glazes literally fall off the clay-body), exploding, or whatever.

Because I consider myself a novice in ceramics, and most certainly a novice in the science of glazing, I don't think I should go into 'details' of how I tested. I would not want, in any way, to be responsible for someone's misinterpretation of my testing procedure (yeah, that's right, I'm chicken - Wuh Oh, this is sounding like the subject of my last post!). Instead, I would encourage anyone interested in the subject to go to the above sites. You can get enough info from the potters.org forum on how to test. And if you need more info, you can always join their listserve and ask for help. Ron Roy is a regular contributor to Clayart's listserve and I see John H.'s posts on there often also. A lot of times potters will specifically ask for Ron or John's help on a technical problem they're having. These 2 guys, as well as the entire listserve community are a sea of information. Have to admit, I quit subscribing to the listserve a few years ago, because I didn't like getting so many e-mails from them, even if only weekly. Once I got the e-mail I felt obligated, or just too curious, to run through it to see if there was anything I may be interested in - one more thing (like the WWW) to get side-tracked by. For me, it is much more convenient to go there for any particular subject I'm interested in. Saves time and uneccessary e-mails/reading. I go to that site for anything and everything concerning a problem/question I may have regarding ceramics.

Also, the potters there mention how the American Society for Testing and Materials ASTM (ASTM C 554-93) suggests testing for thermal shock, which will be my next step. I could not find on their site exactly where they explain the procedure on how to perform this test, but was able to pick up enough info in my Mastering Cone 6 book AND at potters.org to do the test; but I'll perform that test using cups, not test tiles. It involves heating the ware in the oven to a certain degree, then quenching in room temp. water, which is a more rigorous test than the first (again, be sure you research how to do this test before actually doing it and proceed with caution!).

And alas, on painting, just playing around with a mini watercolor (4.5" x 5") of a fallen oak leaf. I really want to get back to painting. Gotta make the time...

Friday, February 20, 2009

Raisingmaine-shy about blogging

I recently came across this interesting post regarding a blogger's concerns about becoming an overly cautious writer on her site(click on her link to read entire story):

I am becoming a shy blogger. Words that used to flow freely from my head onto paper and off to you are now being edited to destruction and my final thoughts just before I post are, ”Yeah So?” thus I post nothing.

It reminds me of when I was in 7th grade and my family moved from the suburbs of Boston to our summer home on Cape Cod.

I wrote a great blog about my niece’s wedding. How I danced so much my thighs still hurt, how very very blessed I am to have nine brothers and sisters and mostly that my children chose to go with me. My overly cautious editing killed it.
I think I need a trip to the woods Raye. I am not sure this venue is the place for my boldness or the place to show slivers of myself, but I struggle writing in any other way.

i don't even blog, and STILL i edit and carefully choose every single word that i say on this site. i have admitted that there are things i won't talk about because i'm never sure who is reading [this was a comment in response to her post/rjd].

I enjoyed reading her thoughts on becoming shy about blogging and over-editing her posts. I could really identify with it. Being new to blogging, I tend to hold back on revealing too much of myself, although for artists, that comes with the territory. Expression requires 'exposure' to some degree. It's the act of exposing via one's posts to the entire world that can be intimidating, at least for me. I'm curious to know how you feel about this. She seemed concerned about remaining authentic to her readers if she holds back too much. But how much is too much? Are you new to blogging and find yourself continuously re-editing your posts? If your a seasoned veteran, do you still do the same, or do you even think about it? Let me know what you think! I hope this clipmark post works this time. I originally had a much better post and lost it. See, there I go, having to re-write and edit again!

Saturday, February 14, 2009

Now Where was I...

Oh yeah, when last posting, I was going down into the hollow to take some pics and assess the damage from the ice storm. Actually, it wasn't as bad as I first thought, given all the damage to people's yards and our streets. This is a pic of some trees on top of the slope that uprooted.
Surprisingly, many of the oaks that completely uprooted were fairly young trees, maybe because of their limited spread of roots. Some of the oldest trees took the storm much better. This image shows what a limited root system the young trees had compared to what a much older tree would have.

Many trees just split multiple times right down the middle of their trunks. This was especially true in town. Lawns look like they're landscaped with bouquets of 'toothpicks'.

Scenes of the bottom of the hollow:

Okay, enough pics of trees already! As I'm posting this, my husband is outside with the chainsaw cleaning up the mess and I need to go help. Back in a bit...

Cleaned up in the yard all day, now it's time to get back to art! I did accomplish one major goal over the past two weeks and that was getting my Etsy Shop set up. This is truly a milestone for me in goal-setting. Although I only have a few things listed so far, I feel that I can get things going now that I'm finally set up to sell on-line. Tomorrow I'll start testing my liner glaze tiles for durability. Will let you know how that goes.

Sunday, February 8, 2009

'Sticky' Mess

What a mess NW Arkansas is! This is what it looks like in probably every town across northern Arkansas - on every street, in front of every house, piles and piles of sticks and other debris from the ice storm of last Tuesday.

I'm going into the hollow in a few minutes to take some pics of the damage. I walked a short way into it yesterday and was shocked. Not just tree limbs and upper halves of trees on the ground but manytrees completely uprooted throughout the hollow. It looks as though the Jolly Green Giant walked through knocking over trees at his whim. Very much like the aftermath of a tornado
or strait-line wind damage. It was too dangerous to go into the woods friday because of the wind gusts. Actually, the wind (I'm guessing) knocked out our power again friday afternoon. It finally came back on around 4:45 yesterday morning. But again, not to complain, as there are still people in our area without power. Once the crew comes to fall the damaged trees, our clean-up job is going to be huge, so for now, we can live with a messy yard.

Monday, February 2, 2009

It came...

Well, we survived the ice storm and what a storm it was. The news media claim it is the worst ice storm on record for Arkansas. I wasn't sure if the storm of 2000 might have been worse, because it seemed to have covered a larger area, but the damage of this storm was significantly worse. Anyway, I know it did more damage to our property and house than any storm we've ever had and was MUCH more stressful, especially Tuesday night.

The popping sound of limbs and trees as they split and cracked under the pressure of the ice was bone chilling. Our electricity had gone out at 12:30 noon on Tuesday, so sitting in the dark made it all the more eerie.
We live in a wooded area and have large oaks sitting right up against the house. The old oak on the south side of our house just couldn't bare the weight. It dropped limb after limb on the roof, each time sending me running out of the back bedroom. Then when all was quiet, we'd open the middle bedroom door and shine a flashlight up toward to the ceiling, making sure there were no limbs protruding. We went through that routine all night. First the old oak tree to the south...then the young oak trees to the west...then the two oak trees in the back yard...then the tall pines in front...well you get the idea. But when morning broke we were able to assess the damage, somewhat.

And it went...

Our electricity finally came back on Friday night. I was in the back yard with our puppy waiting on him to 'do his business' when the flood light flickered and then the whole house lit up in all its glory. I hooted and hollered, then our next door neighbors did the same as their house lit up too. Ahhh, a hot shower...

The house has a small hole in the south side from the old oak tree and it looks like one of its limbs may have punctured the roof, but all-in-all I think we were luckier than a lot of folks, so I'm not complaining, we have a lot to be grateful for, but I will truly miss our trees. All of the ones in the front will have to go, and of course the old oak. So many memories. But the woods are dynamic and it's just nature's way. I think that's why I love nature so much. I know that when I go into the hollow this time, there will be new wonders to discover. I will write more on this incredible storm and put up more pics later. If you want to see videos on the storms, of course there are dozens on Youtube. Just do a search for NW Arkansas ice storm '09.