Another tie dye bowl

I made another one of my tie dye bowls a few weeks back. This time I used a different pot to melt the scrap glass. Instead of having three rectangular holes radiating out from the center, it had five round holes like a five spot pattern on a dice (or is that die?) or domino. Again, how the glass is loaded into the melt pot makes a big difference to the finished disk the melt pot creates when it's heated.

I had a pair of bowls that didn't turn out right. The glass split down the middle of each of the bowls when it was slumped into the bowl form and I couldn't fix the problem. I tried a few times to remelt the glass into a flat sheet and then reslump it into the bowl form, but the same problem happened each time.

I'm told by more experienced heads than mine that it's either a result of mixing opaque and transparent glass in the same bowl or an incorrect slumping program where the glass was heated too quickly and dropped too fast. Since all three of the bowls that I created using a mix of opaque and transparent had the same problem and other bowls with either all transparent or all opaque turned out fine, I'm guessing that's the issue. Lesson learned - no more mixing opaque and transparent side to side. On top of each other is fine, just not in the same layer.

At any rate, since I couldn't make the bowls work, I decided to recycle them in the melt pot and this bowl is the result. I mixed in some clear glass with the bowl shards - yes, it did feel very satisfying to smash them - and then set the melt pot in the kiln to do its thing. I love the ripples in this bowl!

Again, it reminds me of tie dye and it created no problems with the mixture of transparent and opaque glass in the slump this time. I guess that since opaque glass is stiffer than transparent, it holds its shape longer than the transparent and that is what caused the splits in the other bowls. This time the blank had the opaque and transparent glasses so thoroughly mixed that there wasn't a large expanse of opaque glass to cause a split. Live and learn!

Next phase...

Well, I didn't get the kiln shelf cleaned off and re-coated with kiln wash on Thursday, as planned.  It's turned out to be more stubborn than I anticipated, even with the four layers of kiln wash that I had laid down.  It needs to be cleaned off with a file and the kiln shelf sanded smooth again in those two spots before I can use it again.  I knew that it would be somewhat of a problem to clean off - that's the whole point of kiln wash in the first place - I just didn't have the first-hand experience with it yet.

So, I'm cheating a bit instead.  When I bought the kiln, I also got about a half dozen kiln shelves in different shapes and sizes.  My thought was that as I started to make a larger number of pieces, I could fire more of them at once by stacking the shelves.  Since each blank is relatively thin - around a quarter to a third of an inch high - I can stack quite a few pieces in the kiln, depending on the sizes of the blanks I'm firing.  When I move on to the slumping, I can't stack as much, since the pieces have much more depth.

I've picked out one of the shelves that will allow me enough room to fire both bowls and I'm coating that shelf with kiln wash now.  I have another layer to go before I can put the bowls in there and get the kiln going.  In my next post, I'll show a picture of the kiln with the bowls on their respective molds, just before I turn it on and heat things up.

By the way, in my last post I didn't show one of the blanks because I thought it would look too weird.  I realized that someone may benefit from seeing and hearing about this, so I thought I would post it anyway.  What you're seeing in this blank is air pockets created during the fusing process.

As the glass gets heated, sometimes when you use thick pieces of glass or many smaller layers between the bottom layer and the clear glass top layer, air pockets can form in the final fused glass sheet.  In this particular blank, I used very thick, laser-cut, dichroic glass geckos and some thinner green leaves over a bed of different shades of brown powdered frit.  As you can see, air pockets formed around the geckos.

I'm not all that worried about it, though.  In the next firing, I'll simply hold the temperature twice as long as I normally would at the last stop before I get to the highest temperature for the slumping process.  That will give the glass time to smooth out before it starts to form into its bowl shape.  When you see the finished piece, you'll see that it has smoothed out and formed perfectly into its shape.  This happened to me once before, when I used some thicker pieces of millifiore rod that caused a large bubble in a bowl blank.  I did the same fix last time and all was well.  I'm sure it will be this time too.

New glass pieces - the good, the bad, and the dead

The new pieces that turned out wellNow that my kiln was back in place and I could start to fuse glass again, I put my first load into the kiln on Sunday afternoon.  When I opened the kiln on Monday afternoon, I had a serious shock - two of the pieces didn't make it through the fusing process!

Molten glass sticks to just about anything, so a release agent is necessary to keep the molten glass from sticking to the kiln shelf as it goes through the fusing process.  There are two ways of protecting the shelf from the glass sticking to it, shelf paper and kiln The broken triangle bowl blankwash.  Kiln wash is a powder mixed with water that is painted onto the kiln shelf, building up several layers to create a barrier.  Shelf paper is a barrier that comes in rolls in varying thickness, from truly paper thin, all the way up to shelf blankets of about 1/2" thickness that can be used to form glass in different ways.  Both accomplish the same thing, but rolls of shelf paper are pretty expensive compared to the cost of kiln wash.  Now that I was working in bulk - seven fused pieces were in this batch - I thought it was time to convert from shelf paper to kiln wash.

So this firing was the first time I was using kiln wash instead of shelf paper to protect the kiln shelf from the glass.  I had put down 4 layers - the package directions only call for 3, but I didn't want to take any chances - layering the washes horizontally, vertically, and in each diagonal direction on my kiln shelf.  Despite the extra layer, there were two spots - one on each of two separate pieces - where the glass had stuck to the shelf and caused friction as the glass heated and cooled and those spots were where the glass had fractured.

Heart shaped bowl blankLive and learn, I suppose... but it was very disappointing after having added the extra layer of kiln wash to be on the safe side, to say the least.  At any rate, I've put an extra layer of kiln wash on the molds that I'll be using to turn the remaining two blanks into their bowl shapes.  Hopefully, that will work.  I've put three layers on the other molds that I've used in my past fusing efforts, but now I'm feeling a little paranoid.

For those of you who aren't already familiar with glass fusing, it's a two step process if you are making a decorative glass plate or bowl.  First you cut and layer glass to form a blank in the shape of the piece that you're creating.  I used a combination of a piece of decorative art glass for the bottom layer, then added fusable glass paint, glass frit (ground glass that comes in varying sized material from a powder to a coarse chunk), stringers (glass rod pulled into a very thin string 1/16" or less in diameter), and laser cut pieces of dichroic glass (glass with a layer of misted minerals applied in a process that causes beautiful effects where the light changes the color of the glass when viewed from different directions), and a clear glass layer on top to add depth and dimension.

Once the sandwhich is fused together to form the blank in the specified shape and size to fit a mold, it goes through a separate firing at a lower temperature where the glass melts just enough to form itself into to the bowl or plate The broken square bowl blankshape.  This is referred to as slumping.  So, once the layers of kiln wash are dry on the molds - the process takes time as the kiln wash needs to dry between each coat - I'll be putting my two bowls back into the kiln for the slumping process, which will probably be happening overnight tonight.

These images show both the sucessful efforts as well as the two fractured blanks that didn't make it.  To make it even more disappointing, those were my first two efforts with the fusable glass paint, as well as my first efforts for those particular shapes.  But at least these pieces do give me a feeling for how the glass paint looks after firing.

Closeup of one of the pendants from the photo aboveThe smaller pieces will be pendants, so they won't be going back into the kiln again - they're done.  All they need is a little sanding to take off some rough edges from the firing process and getting a bail glued on.  (The bail is the jewelry finding that allows the pendant to hang from a necklace.)  I just tucked the bails in place under the piece for the photos, but after looking at them, I think that the ones I used for the photos don't look substantial enough for these particular pendants, so I need to go through my stash looking for some more appropriate bails to use.  I think I know just what will work, the hard part is finding them...  Wish me luck!