If you follow me on Facebook or Twitter, you know that I have a new bottle mold that I’ve been playing with. It is a spoon rest/dish shape with a swirl pattern in it. The sample bottle I saw looked great. It never dawned on me to ask for directions on how to use this slump mold. I have a slump mold that is basically the same shape, but without the design. I assumed I could use the same firing schedule with just an increase in the hold time at the highest temperature. This I reasoned would be necessary for the glass to conform to the design.
Never assume anything. On the first try I simply used my existing schedule to see what would happen. Not much really; you couldn’t even see the design. I doubled the hold time on the second try. It left a barely perceptible impression. Third time’s a charm… right? Nope! I let the bottle sit at the process temperature for 1 hour. It left an impression, but you couldn’t really see it from the top. See the pictures below.
I finally decided to go to the mold maker’s website and read what they say about it. The first thing they do that I don’t is to put the bottle directly in the mold. I have been flattening the bottles first, and then putting them back in the kiln with the mold to shape them. Somewhere I read, or was told, that molds will last longer if you use them at lower temperatures. I am thinking now that maybe this was bad information. At this moment I have the mold back in the kiln with a bottle using the schedule recommended by the mold manufacturer. Well almost. I made a few minor adjustments for my kiln. We shall see what tomorrow brings.