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