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Archive for November, 2015

I recently bought a ceramic ruffled plate mold at a sale for $6.  What a deal!  However, when I used the mold the first time, the resulting plate did not rest flat on the table, and instead rocked driving me crazy.  I realize that not all tables and countertops are completely flat either, but this was enough of a rock that it was clearly an issue.

At first to resolve the issue, I put the plate back into the kiln and refired to only 1050 degrees F rather than 1200 degrees F but the result was less of a ruffle on the plate.  Time to figure out how to resolve the real issue.

Ruffled Christmas Plate

Ruffled Christmas Plate

My husband works with metal which is very exact and helped me figure out how to solve the problem.  Here are the steps I used.

1.  Figure out which diagonal is rocking and mark that both on the glass and the mold.  It is really important to keep track of this diagonal as you work through the issue.  The glass is rocking on this diagonal because one of the corners on the mold is not low enough for the glass to slump into.

2.  It doesn’t matter which of the two corners you work on that diagonal, as long as it is one on the problem diagonal.

3.  Use sandpaper (I used 220 grit) to sand down the ceramic mold in that corner where the glass needs to slump lower.  The goal is to sand it far enough that the two corners can slump equally.

4.  So how can you tell if you have sanded the mold far enough?  Take a small ball of clay and put it on the mold where you are sanding at the low point.

Mold with Clay Ball Placed where I Need to Sand

Mold with Clay Ball Placed where I Need to Sand

5.  Place the glass plate onto the mold and flattened the plate into the mold squishing the ball of clay.

Clay Ball Flattened Between Glass and Mold

Clay Ball Flattened Between Glass and Mold

6.  When you lift the plate, turn it over and see how thin or thick the clay is.  This thickness is how much farther you need to sand to get the mold even.  You can test this by taking the glass with the clay still attached and placing it on a known flat surface to see if it lays flat.  My plate no longer rocked with the clay so I knew this is how much farther I needed to sand.

Thickness of Clay is How Much I Need to Sand Away on the Mold

Thickness of Clay is How Much I Need to Sand Away on the Mold

7.  Sand some more and repeat the test until you get to where the clay ball thickness was miniscule.  Ultimately I learned to sand this slightly more than I thought I needed as I am guessing re-kiln washing ended up adding slightly to what I had just sanded.

8.  I then kiln washed the mold and re-slumped the plate.

Final Test Plate with Nice Ruffle and No Rocking

Final Test Plate with Nice Ruffle and No Rocking

Ultimately I did this test and re-firing twice to get it right but it does work.  And remember that many surfaces which we think are flat are indeed not flat.  My husband owns something called a Surface Plate which is designed to be flat for just such testing.

For me this was worth the effort as the rocking really bothered me.  I did have to laugh though as I later realized that many of my store-bought regular dining plates did not sit flat on the table either due to either typical manufacturing inconsistencies or tables and counters not always being flat.

I loved learning how to resolve the issue with the mold and make my glass plates better.

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Recently my husband was placing an eBay order for some electronic components from China and noticed if he got to a certain amount, he got a discount. He looked to see what else was available on their store and noticed some stainless steel cookie cutters. He is always on the lookout for stainless steel for me as it works so well with kilns.  They were three small different size circles and were just a couple of dollars for all three.  Awesome!

It was hard to be completely confident that they really were 100% stainless steel, so when they arrived I fired one to 1400 degrees F to see if is flaked and it came out the same as it went in with a little less shine to the metal. Now ready to test with glass.

I decided to use each of the three rings differently. First I lined each ring with Bullseye Thin Fire. And yes, if you look closely at the picture you will notice I had the wrong side facing the glass. I was surprised, but it didn’t seem to matter.

I had made some pattern bars with one color being steel blue opalescent and I wanted to see how the pattern bar would melt, so I added one rectangular slice of the pattern bar to one of the rings. For the second ring I nipped some rods into 3/8″ pieces and set them on end with pieces of clear Tekta on top. The third ring was comprised of pieces of Tekta mixed with green and red confetti and green, red and white stringers and some small pieces of dichroic course frit for effect.

Stainless Steel Rings with Glass Before Firing

Stainless Steel Rings with Glass Before Firing

  • The glass in the smallest ring flowed all the way to the ring and came out very nice and for the purposes of testing how to use the ring worked out quite well. After some smoothing of the edges, fire polishing and a bail, it will be ready to be worn as a necklace.
  • The second mostly filled out the ring, but I wish I had added more color and covered the dichroic pieces with Tekta as they didn’t flow as well.
  • The pattern bar melt did not fill out the largest ring, but it was still a good way to contain the glass melt.
Glass after Firing in the Stainless Steel Rings

Glass after Firing in the Stainless Steel Rings

Since I have a very hard time getting circles for jewelry and wine stoppers to end up both the right size and a perfect circle, I think finding stainless steel circles the right size is the best way to go.

Over the years I have bought shaped cookie cutters and was planning to use them as templates to contain frit and then remove them before firing. However, now I that I know these circles work so well, I might give them a try for say Christmas ornaments. If you do give this a try, make sure you test your cutters first to ensure they are really stainless steel.

As a side note, I have read that using chalk with thin fire around it works well to create holes in glass, so I think a Holiday shaped cutter with chalk will be a great next test and will make a nice ornament.  Stay tuned for the results of my tests!

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