As an early tester of PMPC Flex, I cam to really enjoy the clay's properties. In the coming weeks and months, I'll be sharing some of my thoughts about the clay with you. For this initial post, I was asked to describe just how flexible the clay is and how long it stays that way, how easy it is to rehydrate, and shrinkage rates compared to PMC3. My results are below.
How long does it stay flexible?
What a great question. For this blog, I was asked to test the flexibility of air-dried PMC Flex clay. While looking through my test clay from a year ago, I found a large piece of clay that was in an open packet. It was rock hard dry. At least it seemed rock hard until I cut into it.
I cut it into two pieces with a razor. It sliced very easily. In fact the new sliced face looked shiny like it was wet. So I took a dental tool to see if it was soft. It was!
I then sliced off a piece and it was flexible. After a year of drying, I could still bend it without it breaking!
Going back to the original question, I cut a rectangular piece of clay, rolled it out 4-cards thick, and left it drying on the counter top for 24 hours. I tested it again after three days and still bent as much as it did straight out of the package. I compared it to the year-old clay and the bend I could achieve with the two pieces was nearly identical.
Please note that drying PMC Flex on a hot plate, dehydrator, or cup warmer made it less flexible. Drying the clay on a cup warmer may be good for drying rings so that they don't flex as much while finishing them in the unfired state.
How well does it rehydrate?
I took half of the dried ball of clay I found from last year and cut it into small pieces with a straight edge razor. I spritzed it with water, mixed it with a pallet knife, and rolled it between a plastic report cover. I repeated the process until the clay could be picked up in a flexible sheet. I allowed it to sit overnight and found the clay as elastic as the newly opened package.
What is the shrinkage comparisons between PMC3 and PMC Flex?
I rolled PMC3 and PMC Flex to the same thickness and cut them into equal round discs.
I fired them at the same time at 1650°F (898°C) for two hours. As you can see in the photo, the shrinkage was identical.
Here are some of my initial findings about PMC Flex:
- The length of time that the clay remains flexible depends on drying technique. PMC Flex dried on a cup warmer/ hot plate became less flexible faster than clay dried in the dehydrator at 155˚F (68˚C) for 15 – 30 minutes. Air drying allows for an even longer flex time. For example, pieces 3-cards thick that were air dried were still are somewhat flexible 24 hours later.
- The thicker the piece of clay, the longer flex time. After 60 minutes the 11-card thick piece of clay still mashed down and sprung back to shape.
- I found that when drying PMC Flex in a dehydrator, the bottom surface of the clay imprinted the texture of the dehydrator. This could be a problem for an item that has texture on both sides. I recommend placing PMC Flex on something smooth until the outside layer is dry.
- The clay stays so flexible that I became concerned about drying it in a dome. Would it loose its shape after removing it from the doming plate to dry completely? This was not the case. It kept its shape for the most part. I was able to reshape the dome after it became mostly dry.
- While sanding the sides and insides of a ring, flexibility became a problem. I had to take care not to ruin the ring while sanding because it wanted to flex and bend.
Until next time, have fun claying around!
by Janet Alexander