Sandcasting the JB Way

[1dave]

An Extension of CASTING.

I mentioned Jay B. Bown way back in 2013 when I started the Casting and Fabrication Threads.

Yesterday I received a DVD from Jack Stamper of Merion VA that he made of JB at a rock show in Florida in 1993.
I knew that JB had traveled to rock shows all over Utah, Colorado, Arizona, and New Mexico, but didn't know he had made it as far east as Florida.
I've extracted some images from that video to illustrate some of his techniques.


JB in Florida 1993

JB lived in Orem UT in the 1970's when Indian Jewelry was in it's heyday. (We were buying silver for $3.00/Oz - scrap silver for half that.) Looking for easier work than his stone masonry, he studied with the Navajo silversmiths in Provo. There he experimented with sand casting. His experiments changed the course of his life. He discovered that somehow in the electromagnetic relm, Like carbon, garnet somehow prevents oxidation.

He invented the "Garnet Block" and his commercial artist wife, Lois, made his first brochure.











Casting sand requires a minor clay component to hold it together when dry.

JB used 3 parts fine garnet sand to 1 part potter's clay.

Green sand (from Wikipedia)

These made of wet sand that is used to make the mold's shape. The name comes from the fact that wet sand is used in the molding process. Green sand is not green in color, but "green" in the sense that it is used in a wet state (akin to green wood). Unlike the name suggests, "green sand" is not a type of sand on its own, but is rather a mixture of:

1. silica sand (SiO2), chromite sand (FeCr2O4), or zircon sand (ZrSiO4), 75 to 85%, sometimes with a proportion of olivine, staurolite, or graphite.
2. bentonite (clay), 5 to 11%
{OR 25% ACTIVA Blackjack Clay (usually white) - special blend of several natural clays resulting a silky smooth consistency specially formulated for optimum pottery workability}
3. water, 2 to 4%
4. inert sludge 3 to 5%
(5.) anthracite (0 to 1%)

There are many recipes for the proportion of clay, but they all strike different balances between moldability, surface finish, and ability of the hot molten metal to degas. The coal, typically referred to in foundries as sea-coal, which is present at a ratio of less than 5%, partially combusts in the presence of the molten metal leading to offgassing of organic vapors.

Green sand for non-ferrous metals does not use coal additives since the CO created is not effective to prevent oxidation.

Green sand for aluminum typically uses olivine sand (a mixture of the minerals forsterite and fayalite which are made by crushing dunite rock).
The choice of sand has a lot to do with the temperature that the metal is poured. At the temperatures that copper and iron are poured, the clay gets inactivated by the heat in that the montmorillonite is converted to illite, which is a non-expanding clay.
Most foundries do not have the very expensive equipment to remove the burned out clay and substitute new clay, so instead, those that pour iron typically work with silica sand that is inexpensive compared to the other sands. As the clay is burned out, newly mixed sand is added and some of the old sand is discarded or recycled into other uses.

Silica is the least desirable of the sands since metamorphic grains of silica sand have a tendency to explode to form sub-micron sized particles when thermally shocked during pouring of the molds. These particles enter the air of the work area and can lead to silicosis in the workers. Iron foundries spend a considerable effort on aggressive dust collection to capture this fine silica. The sand also has the dimensional instability associated with the conversion of quartz from alpha quartz to beta quartz at 1250 degrees F.

Often additives such as wood flour are added to create a space for the grains to expand without deforming the mold.
Olivine, chromite, etc. are used because they do not have a phase conversion that causes rapid expansion of the grains, as well as offering greater density, which cools the metal faster and produces finer grain structures in the metal. Since they are not metamorphic minerals, they do not have the polycrystals found in silica, and subsequently do not form hazardous sub-micron sized particles.

You may find a different combination more to your liking. Crushed dunite as used in aluminum casting or olivine may serve better as the sand. Try varying the amount of clay.

4 to 1 = 25%, 5 to 1 = 20%, 6 to 1 = 16.7%, 7 to 1 = 14%, 8 to 1 = 12.5%.

Back to JB, his combination allowed him to wet the surface of his garnet blocks and re-work the sand-clay surface when it became marred. He liked to rub it smooth with sandpaper to remove contaminants.



This allowed him to carve patterns into his garnet blocks, melt scrap silver on them, melt the silver, then flatten the silver with the 3" block, then extract the cooled silver casting. He could then dump on the carved out material, wet the surface, work it back into a paste, smooth it out, and let it dry.
He was then ready to do it all over again.

[1dave]

Part 2


Making plate from scrap silver is easy with his system. just place the scrap on the 6" block and start melting it. He used a pick he made by drilling and driving a bicycle spoke into a piece of wood, then sharpening it to a fine point. With it, he shoved the pieces of silver together, and flicked out the pieces of other alloys he noticed in the melt. Once the silver balled up, he "snuck up on it from the side" and flattened it out with a three inch block.





Then he used the "old fashioned rolling mill" of hammer and anvil to further flatten it,
re-heating from time to time to anneal it.

[1dave]

Part 3

And now the really fun part, Jeweler's Cast !

He hit on an easier way than carving patterns. Casting AND Fusing at the same time!

Remember, JB used 3 parts fine garnet sand to 1 part potter's clay to make his Garnet blocks.

In a similar way, he made a soft jewelers sand cast mix of 3 parts fine silica sand and 1 part potter's clay, usually three - six tablespoons in a mixing bowl, 2-4% water, then spooned out whatever was needed onto the 6 inch block.

He needed to make a granulation image. He flattened and smoothed the mix by tapping the surface with a 3" putty knife and a ball-peen hammer, scratched the pattern on, then filled the various parts with the desired silver spheres. He then again placed the putty knife on top and tapped the spheres down flat into the sand.
He placed a previously prepared silver plate on top, then heated it to the point where the silver flowed, but stopped before it began to ball up. Quickly placed the 3" block on it to force it all together. I think he did this several times to assure all had connected, then used the tweezers and pick to pry it out of the sand, dipped it in pickle, then water with baking soda, brushed the pattern with an old tooth brush, and got just what he wanted.

He takes the old jeweler's cast, breaks it up in the mixing bowl, adds water and uses it again on the next project.

[1dave]

Part 4

at the 1993 Florida show, he prepared the Jeweler's Cast, and pressed an eagle form down into it. He then took a piece of silver wire and formed it into the representation of a snake. He placed it near the eagle claws, then used the 3" putty knife to force the snake flat into the cast.



He could have pushed the casting medium around portions so it would protrude more from the final product.



Next, a piece of silver plate was placed over the design.



Brought to flow temperature, pressed down with the 3" block and extracted.



The eagle was cast, the snake was fused to the plate.



What can you do with your imagination ?