Archive for October, 2011

Recently I made a 8″ square plate using some red and green glass trying to get a piece ready to sell for the holidays!    With Bullseye glass, you end up with what are called soft edges on the sides of the sheets (the natural edge from their production process) and so I wanted to incorporate these soft edges into my design.

Let me describe the layout:

  • a 7-3/4″ 2mm thick sheet of clear
  • a 7-3/4″ 3mm thick sheet of what I call Christmas glass
  • using the soft edges, I wanted them to drape of the sides of the plate so using their width of about 1″, I put about 3/4″ on each edge and then had about 1/4″ hanging over the side
  • and for these edges, I then overlapped them at each corner

I loved my design, fired it using a normal full fuse schedule and then opened the kiln when it was done!  Argh!  It had a crack down the center of the piece of Christmas glass.

Cracked in the Middle - Hmmm

I had never had anything like this happen before.  So I wasn’t sure it was my firing schedule and I had gone too fast, or something wrong with my layout, or something wrong with the Christmas glass.  So I decided to send an email to Bullseye and say, “Help!”  They gratiously asked me many questions about kiln, position in kiln, type of kiln. layout of glass, thickness of glass and so forth.

Bottom line is that in the center, it was only 5mm thick and on the corners where I had overlapped things, it was 11mm thick.  So as it was heating up, it could not heat evenly across the entire plate and hence it cracked.  According to Bullseye, another possible problem could have been a large bubble in the center due to the center having the least thickness.

How not to have this happen?  Basically, two options.  The first is to make a design where it is even across the piece.  However, sometimes this might not allow me the creativity that I want.  So next option is to heat the piece up very, very slowly and the same when annealing it on the way back down to room temperature.  I do plan to try this again (perhaps with a cheaper piece of glass) and use a very slow firing schedule and see what happens.  Experimentation is so much fun!

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In an effort to save money, sometimes we can make the wrong choices that in the end cost us more money.

When I first decided I wanted to try my hand as making vases by slumping them over a stainless steel mold, I went shopping for the mold.  The molds I found ranged from $20 upwards of $50.   There was a similar shaped mold called a Martini Shaker (yep!) which I could buy at Target for $10, so I decided to go that route and save myself the $10.

Hmm, perhaps not such a good decision.

The difference between the martini shaker and a mold made specifically for slumping vases is the bottom where the martini shaker actually curves inward.   No big deal you might thing until you start to use it.  If I was lucky to know exactly when to stop the slump then you would be right.  No big deal.  But most of the time since I am still learning how to tell when to stop the slump, it would go too far.  And what this means is that the glass would curve slightly inward at the bottom such that when it was cool, I would try to remove the martini shaker and alas, it could not be removed.

Back into the kiln, this time upside down, heating is slowly back up to slumping temperature, checking it regularly and trying to remove the martini shaker using some needle-nosed pliers.  I think in one case, I did have success.  But often as the glass would expand, it would leave a mark or worse a crack where maybe a fold had been.  And in one case, I had just checked the kiln and set a time to check again in 5 minutes.  And it was amazing how quickly the shape changed and fell away from the martini shaker.  Check out the picture below.

Slumped Vase Gone Awry

So long story short, use the right tools.  Since I bought a mold specifically for glass slumping of vases, they have not all come out beautiful, but at least they have all easily removed from the stainless steel mold.

Correct Stainless Steel Mold for Glass Vase Slumping

Completed Good Vase!  Compare it with picture above of red vase to get an idea of what happened with the red one.

Brown/Taupe Fused Glass Vase

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While I tend to be a planner in my daily activities wanting to always have a schedule and a list for everything, I guess I just tend to wing it when it comes to my glass work.  I go with the moment on what I feel like making which may be why I like the freedom of this hobby so much!

However this is no excuse for not thinking, which I need to keep reminding myself.

Recently I made a drop vase and decided it needed more stability on the bottom.  So I made a small disk that I thought would be a good size for stability.  I then put the drop vase and the disk back in the kiln to tack fuse them together.

Disk Added for Stability

The disk I slid in on the kiln shelf and then added the drop vase back into the drop mold adding a little height by putting some fiber paper between the drop shelf and the posts.  All was looking good.

I fired it, a little afraid that the drop vase may want to do more slumping since I had taken it to 1200 degrees F.  But it tack fused nicely and didn’t seem to affect the drop of the vase.  So now after cooling, I opened the kiln and gently lifted the vase and uh-oh!  The disk was too big to fit through the hole (disk was 3.5″ and hole was 3″) and so now I had a lovely vase with the ceramic mold stuck.

My husband helped me “break” the mold so that I could perhaps reuse it for doing a similar tacking job where I wasn’t taking it hot enough for the mold break to matter.  Thanks!

Ceramic Mold After We Broke It

I learned though to at least always stop, look at what I am doing and think about any possible issues.  This doesn’t mean I won’t make any more mistakes as I am quite sure I will, but I know I won’t make this same mistake again.

Final Vase

BTW:  The disk for stability is a really nice thing.  I got this idea from Christine at Masters Glass Art, http://glassart.wordpress.com.

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I recently embarked on trying my hand at a plate with straight stringers all lined up.  I am not sure I have the perfect magic recipe, but here is what worked for me.

My first attempt was to take my stringers, lay them all next to each other on top of a clear base.  I was afraid that as they fused and spread, they would not stay straight, so I put a dam on the outside edges.

First Attempt at Straight Stringers (put dam around them)

In general, it wasn’t a bad attempt as most of them were straight, but since I had dammed it, I think as it spread it pushed some of the stringers up and so you can see about 1/3 from the top a purple one that is slightly higher and spread more than the others.

My second attempt was to first tack fuse the stringers to a sheet of clear.  The clear lines were also clear stringers.  And the tack fuse, I then took them to a full fuse.  I was hoping by tack fusing them that when they then fully fused they would stay straight.  Was I wrong!  This was the worst one as you can see in the picture.  Lots of wavy lines.

Second Attempt at Straight Stringers (tack fused first before full fuse)

Now on to my third attempt.  For this one, instead of completely covering the clear sheet with stringers using clear stringers between the colored ones, I decided to just fuse the colored stringers to the clear base and have the base itself be the clear stringers.  So using a ruler, I carefully laid out the stringers keeping them equidistant apart and then did a full fuse.  This worked the best of all.

Third Attempt at Straight Stringers (evenly spaced on clear base)

So what did I do with my good pieceof straight stringers?  I put it between colors that matched the stripes!  A nice final piece to show for my testing.

Completed Piece with Straight Stringers

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