Sand Casting - see images below -

The Next class will be scheduled after we know what second session classes make. If you are interested in taking this workshop. Please let me know.

Please contact me directly with any questions or if you want to be added to my notification list of students. You may email me at mail@joshdopp.com

 

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Sand Casting is the process of ladling molten glass from a furnace and pouring it into sand formed cavities. This page will go over various aspects of the process, please read over the entire document before coming to class.

Please bring two or three projects of various sizes, which we can sand-cast. It is nice to have options just in case one of the ideas does not lend itself to the particular class. Your projects should be no bigger then a shoe by volume and no smaller then a tennis ball. Keep in mind that it is difficult to pour the glass into tightly restricted areas and to pour around corners and into appendages. For best results consider shapes that are more monolithic. ­ Your models and forms should be somewhat sturdy because you will need to firmly press them into the sand. Also, they should not have any undercuts which would impede them being taken out of the sand. That being said, it is possible to use multiple items to press into the same sand cavity or form. The resulting glass form can then have undercuts, as it will be pulled out of the soft sand. Copper wire gold and silver can be used as an inclusion, as well as, color powders and frits. Additionally, you can make an inclusion at the bench in glass which can than be added to the mold or dropped into the ladle. Please wear pants and maybe a long sleeve shirt, no sandals. Also please bring a pair of work gloves.

 
It will take us about an hour to prepare the shop and molds for the first round of casting. Subsequent castings won’t take as long. Students will prepare the sand by screening and wetting the sand. The process of screening the sand is known as riddling. If you know of any good riddles now would be the time to share them. We have two kinds of sand at MAC right now. One is more course play sand and the other is fine. The fine mix is what is called a Green Sand mix and comprised of Olivine sand 90 mesh and Olivine 180 mesh With 5 to 10 percent Bentonite. Information on the difference between olivine sand and silica sand here. The sand is mixed with water. For a hundred pound of sand it will take approximately a gallon of water. The sand needs to be wet enough that it will stay together. The consistency is correct when a lump squeezed in the hand retains its shape even when it is tossed into the air and caught. Some students may wish to place the projects in small boxes some may choose the large sand box. The large box can accommodate many pieces. But be considerate of your fellow students work area. Care must be taken to accommodate the model. Sand has the tendency to fall in on it self; if you are careful you may-be able to scoop out that which has fallen in and put it back if need be. Re-pressing the model and wiggling it side to side may help to confirm the walls of your mold. If small pieces of sand fall in they can be taken out with a wet Q-tip.  
More on pressing your projects in the sand: your form needs to be sturdy enough that you can exert considerable pressure on it as you press it into the sand. Once your piece is in the sand be sure to pack the sand around your form to ensure that the sand is firm and pat the surface sand around your form. This will help keep the sand partials from blowing around and ending up in your project. Pressed down with the fingers, starting gingerly but progressing until it is compacted under considerable pressure. The degree to which the sand is pressed against the model will affect the detail achieved in the casting. More pressure will yield a better result. You may need to have some type of handle. Undercuts are possible only by adding them later to the initial cavity formed. I.e. think of a bowl and then using a stick to press into the sides, which would create little fingers.  

When the impression in the sand is finial we spray a mixture of water and molasses into the cavity. The molasses coating is then torched resulting in a hard shell. I then add a thin coat of carbon with the use of the Acetylene torch. This keeps the glass from sticking to the sand. The mold is now ready for glass or for you to add color and or any type of inclusions.


Color: The way to add color is to put colored powders or frits into the sand mold after it is ready for glass. Also hot inclusions can be added. Small elements can be made in the hot shop and dropped into the glass pour. - If you use copper wire or other metals remember you can stick the metal into the sand so that it protrudes from your glass object this is helpful for later attachments and hooks.

 
 

When everyone who has his or her molds in the common sandbox is ready I will ladle the glass out of the furnace and into the sand. I will need help with a couple of things. First the door to the furnace and then sometimes it is helpful to have the rim of the ladle swept (so to speak) with a pair of shears. The glass on the rim is yanked and pulled away allowing for a clean pour. Sometimes I just pour from the other side of ladle to avoid this step. When the mold is full of glass I will attempt to trail off the glass but often it is necessary for someone to snip the glass trail so that I can be separated from the ladle.


The hot glass may have bubbles at the surface, which can sometimes be popped with the use of an oxy/acetylene torch. Care should be taken however not to burn the glass. Over heating at very high temp will result in a yellowing of the glass. The back of the piece will loose it temperature quickly, so we will you a torch to keep the edges and appendages warm while the underside cools. Poke vent holes under and around the poured casting, and use torches to evenly cool the glass. When the glass reaches 1150F, we dig it out of the sand and placed on a wood board. Some of the sand is brushed off. It is then loaded into an annealing oven to cool.

 
 

Depending on class I think we will be able to do at least two pieces per person depending on the size. Nonetheless I think it a good idea to bring three projects. It is nice to have options in case one of the ideas does not lend itself to the project. -

 

left Bertil Vallien check out this web site. One of my favorite glass artists is primarily a sand caster.

 
 

As with all of our projects there may be a need to do cold working in order to clean off the unwanted areas or to enhance the piece. There is only limited Access to the cold working areas in connection with this class. Arrangements may need to be made. The studios cold working shop is valuable for rental and private lessons may be arranged. Additionally, I regularly offer a class on cold working please takes a look at the class syllabus


Do some research on the web for more information and inspiration regarding sand casting.

Here are images from my Casting Class in the fall of 07 of our sand casting project.

As a side, but related note, I want to mention the use of Graphite molds for glass casting. Graphite is widely used by artist and industry to achieve reproducible and highly controlled forms. Additionally the graphite when used with smooth forms has no texture problems other than the possibility of surface chill marks. Graphite forms can cast very large pieces of glass. Look at the work of John Lewis for more examples. below  

Here are some web sites which will give you a better idea of the possibilities.

Please do some research of your own and if you find anything interesting email me the link. Thanks

I recently found these great YouTube clips by Linda R Fraser. check them out.

Linda R Fraser sandcasting course clips

   

bertilvallien Cheek out this web site. One of my favorite glass artists is primarily a sandcaster.

Mayne Island Glass

PVCC class in Mexico VIDEO

Glass Artists web site with good info on the process we will be doing.

Leonardo Glass

 

Tina Lindstrom

Moltendesign

Vitroglyph

Spirolyonglass

Neal Drobnis

 

 

     
Images of professional artists

More shots from the Mesa Arts Center workshops

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