Posted on

Q & A Monday – March 11, 2013

Jodi McRaney RushoWelcome to Q & A Monday, which is all about answering reader questions.  I’m presenting a demonstration about making your own texture tiles this coming weekend for the Glass Art Guild of Utah, so all our questions today are about molds.  If you have a question, send it on over, I just may have an answer!  (I’ve removed personal details and names for privacy.  If you asked a question and would like your name listed with a back link, just let me know.)

  • Q:  I am SO glad I found you online and am now a subscriber to your  newsletters, only thing is I’m bummed you are located in Utah! I am in  Oregon and would LOVE to learn how to make my own molds like the ones you show in this link:  http://glasswithapast.com/bottle-glass-and-kiln-carving/ – do you have any kind of online class I could “attend” or something like that? I own a Trio glass kiln, and could probably “rent” some time at my local art college to fire a ceramic mold to bisque level  – My experience is very  limited (no clay work ever), I basically got interested in glass art and bought a Trio (bottle slumping kiln) before I had ever even worked with glass and kind of just figured out a “recipe” how to make wine bottles into serving trays, etc. and now I’m hooked (as I thought I would be!). Any thoughts/advice for building my own (wine bottle slumping) molds/tiles (like the ever so popular “Bon Apetit” mold see below – I own this one and use it and love it but I’d love to make personalized molds with my own artwork) and also tile making molds like you feature on your site?
  • A:  It really isn’t as difficult as you would think to make your own molds. In fact, I keep thinking I must be missing a step because it is so easy! I started out by going to the local ceramic store and telling them what I wanted to do: bisque fired white clay tiles with a texture on them. They helped me figure out what kind of clay to buy and what cone to fire it too. I happen to have a ceramic kiln, so I can fire my own, but the ceramic store offered firing for something like $3/tile. You’ll need to wedge clay to get the air bubbles out. I experimented with just cutting slabs off and they all cracked, so the wedging is critical. I usually roll my slabs out to 3/4″ thick so when they dry they are 1/2″ thick. It’s easier to keep them flat that way. Then put them on a thick pile of newspaper or sheetrock or concrete backer board to dry with plastic over the top. Tiles have to dry sloooooowly or they warp. I check mine every day and press them flat again until they are too stiff to bend (it’s easy to break them in half, press gently, and, of course, once they are too dry to bend, don’t press them!). When you are making the texture, 1/8″ is not quite deep enough, 1/4″ is getting a little too deep. Make sure there are no overhangs that glass can get caught on. You could also check into the community education programs (if they have those in Oregon). Here we have very inexpensive classes that are after hours at the local high schools, that would be a good opportunity to work with a teacher and use their equipment!
  • Q: Could you please refresh my brain on the class I took from you? What kind of clay did we make our tile mold out of?  How was the tile fired?  Whats the firing schedule for doing glass on top of the mold?
  • A:  We used lowfire Whiteware clay that bisque fires to Cone 06 on a slow or medium ramp firing schedule.  The firing schedule for glass depends on the kind of glass.  If you are using art glass, should be the same as any other mold.  If you are using recycled glass (window or bottle) use the fusing schedule from here:  http://glasswithapast.com/recycled-glass-firing-schedules/
  • Q:  Can you use plaster of paris to slump on?
  • A:  You can use plaster of paris to slump on.  The plaster will become fragile after firing though because the high heat breaks down the chemical bonds in the plaster.  Just be aware it will probably not be a multiple firing kind of thing.  You can also use Pottery Plaster, which is a harder, denser plaster.  It will hold up a little better, but will also eventually break down.