Answers About the Molds
Q: Why do you sell a small Quick-Release separately from the Quick-Release set?
A: Some folks have more than one wheel in their studio or classroom.
Q: Why do you sell a large Quick-Release separately from the Quick-Release set?
A: Some folks want to pour more than one mold at a time.
Q: What are the flat bat molds for?
A: The flat bats are for throwing everything that you don't want to throw on a domed bat. The 12" flat is the most popular bat mold for making standard bats for the wheel.
Answers About the Plaster
Q: Can I use Vasaline or liquid detergent for a mold release?
A: A liquid detergent can be substituted but several coats will probably be necessary, and any foaming can create imperfections on the surface of the mold. We recommend Pure Lube which is a thicker liquid, cocoa oil based soap, that doesn't foam a lot. It is manufactured by Laguna Clay Co. and likely available at your local ceramic supply dealer.
Q: I forgot to use a mold release and my bat won’t release from the mold. What can I do?
A: Soften the plastic enough to aid in the release of the bat by warming it with a blow dryer, or place in the sun for 15 minutes.
Q: How long do I leave the plaster in the mold?
A: Thirty to 60 minutes, depending on the size of the mold. Don't leave it in overnight because plaster expands a lot. It should heat up and then cool down before removal. If it doesn't heat up then your plaster is old.
Q: How thick should the plaster be before pouring it?
A: About the thickness of pancake batter.
Q: My plaster mold has small imperfections on the surface. What should I do?
A: They are easy to smooth out with a fine metal rib. Best done before doing the thorough drying.
Q: Can I substitute Pottery Plaster No. 1 with a different plaster?
A: Plasters have different absorptive rates and set up times so Pottery Plaster No 1 is advised. Plaster of Paris, for example, sets up too fast.
Q: Can I add Hydro-stone to my plaster mix to make my bat stronger?
A: You can use a small amount (15%) in the mix but it will make the bat denser and less absorptive. If adding a high relief design to a bat you can reduce the wear by strengthening the mix with Puritan or Duramold plaster.
The flat bats can be strengthened with Hardware cloth or window screen which will not affect the absorption rate.
Generally though, the domed bats do not need strengthening.
Q: Can I add perlite to lighten the weight of the mold?
A: Expanded perlite (available from a nursery) can be added but you should limit additives to 10% by weight. Counter the loss in strength by adding a fiberglass mesh like Scrim cloth or window screen.
Answers About the Bats
Q: Why is my bat wobbling up and down, not seating flatly on the wheel head?
A: Brush a little Red Iron & water on the wheel head bolts to see if they are making contact with the plaster bat. If so, carve out more clearance.
Brush a little Red Iron on the circular nub in the center of the Quick-Release to make sure it is not making contact with the mold. If so, then create a little clearance.
Q: My plate is not releasing from the bat for several days and then is cracked when it does release. What is causing this?
A: Your bat was probably not given the thorough initial drying that it needed to drive off the water used in the plaster mix. Force dry your bat after you’ve poured it. Warm air flow is best but not over 120 degrees. A dry bat should release your plate in about 24 hours. Drying molds properly promotes good strength development, uniform absorption and reduced efflorescence.
Q: My new bats are mushy instead of hard and dry? What is causing this?
A: Old plaster that has not been kept dry will not set up properly. For best results, store plaster indoors in a dry, stable environment (Lidded barrel). A good plaster mix will get very warm from the chemical reaction that takes place while it is setting up in the mold.