How to make a 12"x18" plaster slab with full measurements! You can use this to wedge your clay on, or to recycle your clay. Directions, supplies list and measurements below!
SUPPLIES LIST:
►No.1 Pottery Plaster (I used 10lbs per mold:: https://amzn.to/3koocwH )
►*Cold Water (for my 10lbs, I used 14 cups)
►Mold for the cast (I used a 12x18 sheet pan:: https://amzn.to/2U6KIQj )
►**Mask (for when you are working with the powder, as you DO NOT want to breathe in plaster powder… das bad)
►Metal or rubber rib (for smoothing out the top)
►Spray bottle of rubbing alcohol (for breaking the bubbles at the surface of the plaster)
►Work space (a space you are willing to get pretty messy. I covered my table with a trash bag.)
►Bucket for mixing (I also lined my bucket with a trash bag for easy clean up)
►Gloves (so you can mix the plaster with your hands and clean up easier)
DIRECTIONS:
1. Prepare your work space and have your mold ready. You don’t want to be setting stuff up while your plaster is setting, get all of that ready first.
2. Pre-measure your cold water and plaster mix in separate containers.
3. Add your plaster mix slowly to the cold water. (DO NOT add the water into the plaster mix, DRY GOES INTO WET)
4. Work the mix with an immersion blender or your hands to get all of the lumps out and ensure the mix is well mixed. (I just used my hands)
5. Pour the mix into the pan. (Since I wanted the bottom of the pan to be the top of my wedging surface, I poured in about ½” first and let that sit about 5 mins while working out the bubbles by tapping the sides, to ensure that part was extra smooth.
6. Pour remaining mixture into the mold. (Pouring over your hand helps reduce bubbles and pour the plaster a little smoother.)
7. Smooth the surface with your favorite rib tool.
8. Tap the sides of the mold to bring bubbles to the surface.
9. Spray the top with a couple mists of the rubbing alcohol to break the surface tension and pop the bubbles.
10. Check the plaster every 15mins, tapping the sides and respraying the alcohol until the mold is firm.
11. When the mold is solid (it will still feel a little cool and damp), you can dump out your shiny new wedging board/clay recycling board (or whatever you’re making). For me, this took about 45 minutes, but I am in Texas and it is July. In cooler months and climates, the plaster could take a little longer to set up.
12. After you remove your board from the mold, while it is still a little damp, you can trim it up a bit with your trim tools, rib, or whatever, to smooth out any sharp edges, lumps, bumps and what-have-you.
13. The mold will take 2-4 days to dry completely, depending on how thick you made it, and the climate where you live.
SHOP FOR SUPPLIES:
*Shopping my affiliate links helps support and bring income to my channel.
►Wilton 12x18 Sheet Pan:: https://amzn.to/2U6KIQj
►No.1 Pottery Plaster, 5lbs:: https://amzn.to/3koocwH
►No.1 Pottery Plaster, 50lbs:: https://amzn.to/3yTom3o
REFERENCES:
►Plaster Mixing Chart:: https://www.aardvarkclay.com/pdf/technical/Plastermixinginstructions.pdf
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