Using Lasers With Paper Molds & Pewter (Bologna Sandwich Casting)

Materials:
2 pieces • 6” x 6” • Plywood (or MDF or similar flat board material)
3 piece • 6” x 6” • Matte Board (or similar flat material)
Pewter
Double stick tape (depending on design)

Tools:
Laser (TechShop)
Hot plate & stainless steel measuring cup (for melting pewter)
C-clamp
Tray (pyrex is good, or a baking sheet)
Jewlers saw & #2 blades
Hand files

Prerequisites:
Laser Cutting & Etching SBU: LAS101 @ TechShop



Step One: Laser Time
• Use CorelDRAW and the laser cutter to cut the silhouette of your design, out of one 6” x 6” pieces of matte board.
     • Refer to your handout from your Laser Cutting & Etching SBU: LAS101 class, for the appropriate settings for your materials on the laser.
     • Make sure to leave at least a 1” border in design
     • Include a V shaped “sprue” for metal to be poured through. Should be 1-2” wide.

• Use CorelDRAW and the laser cutter to etch a texture or design, onto the two remaining pieces of 6” x6”  matte board.
     • Refer to your handout from your Laser Cutting & Etching SBU: LAS101 class for the appropriate settings for your materials on the laser.
     • Include a sprue!
     • Remember that what is etched into this mold will be raised in your metal casting.
     • Also, any text needs to be reversed.


Step Two: Casting
• Line up your matte board mold pieces. Use double stick tape if you have any “floating” pieces, or need to precisely line up multiple layers.
• Sandwich the matte board mold layers between the 6” x 6” pieces of flat board (plywood or MDF) & securely clamp together with at least 2 c-clamps. Position this entire set up in a tray of some sort (pyrex or baking sheet).

• Set your pewter in your measuring cup, your measuring cup on your hot plate & turn ON (pewter will melt around 400 F depending on the specific alloy).

• Gently shake measuring cup handle to check and see if pewter is molten. Once it is up to temperature it will evenly move as one liquid volume.

• When pewter is molten, pour in one SLOW & FLUID motion.
     • Position the measuring cup lip as close as possible to the sprue.
     • If you have a shaky hand, set up a wooden block or something to use as a hand rest.
     • Pour until the mold (including sprue) is completely full.


• Wait until pewter cools (about 10 minutes).
• Carefully open mold and enjoy your castings (or if they didn’t come out right, melt down & cast again)!
• Because pewter has such a low melting temperature this mold is re-useable! It even tends to work better after it warms up (by the 3rd casting or so).



Step 3: Finishing
• Use a jeweler’s saw with a coarse sawblade (#2) to cut off “sprue” (negative in mold) / “button” (positive in metal).
• Use a hand file to remove any “flashing” and clean up and necessary edges.


I made it at TechShop! Check out there website: www.techshop.com!


History:
When I was a student at the College for Creative Studies, Tom Madden taught me Bologna Sandwich Casting (BSC). Years later, unable to find any articles on BSC, I asked Tom if there wasn’t another name for it. He told me he wasn’t sure, but to ask Paul Mergan. I found Paul through the Michigan Silversmith Guild and he told me he came up with BSC after Fred Fenster inspired him by teaching him to cast ingots of Pewter in a folded piece of paper. Paul told me he wanted to show his own students the “magic” of casting pewter in paper, but with more controlled results. He devised away to cut (traditionally with an x-acto knife & jewelers saw) & and layer sheets of paper/board and cast into them. As him process became more and more complex, he started color coating his layers, and the “yellow” layer soon became the mustard, the “green” the lettuce and so on and so forth, until he named the whole process BOLOGNA SANDWICH CASTING.

Phew. I hope I did it justice.