Welcome to Michigama Glass..... I hope you enjoy your visit. In this blog I'll be featuring projects, products and information on traditional stained glass, warm glass (kiln formed glass), mosaics, glass casting, ornament blowing and information on products and processes... So please come by often and see what we are up to....

Monday, April 5, 2010

Mold Making: Step 1 in casting glass....

For my very first project in glass casting, I decided to try and make two large paper weights. I chose this project for one main reason and that is that it was an easier choice than picking a detailed carving to carve in wax, create the mold and then hope it turned out in the kiln.  Because I chose to use an item that is NOT made from wax, I must create a mold from latex to create the wax version of the object.  The only time you'd want to create a latex mold from the wax original is if you want to make more than one cast of the original wax item. This is done, because the wax version of the object is going to be used to create a mold in plaster of paris and then melted out. Thus losing the ability to make anymore casts from the original.... 


1.) Item to create mold from.  In this case, two wooden toppers I purchased from Michael's.
2.) One 16 ounce container of liquid latex. Purchased from Michael's for $14.99. This is enough to do 3 small molds. (You can purchase a gallon of liquid latex for $55 online. For larger projects this is a must).
3.) One inexpensive paint brush to brush the latex on.

Applying the Latex
There are several ways in which you can apply the liquid latex:

1.) You can dip the item into the liquid latex, making sure to coat the entire mold evenly.  It is important to make sure you have a way to suspend the entire object, so that it dries thoroughly. 
      * I only recommend this process if your object is capable of lying flat or you are wanting to make a cast from an object or design on a flat surface (see pic at bottom of section). Dipping the object wastes a great deal of latex.
2.) The preferred method is to use the brush and apply a layer, allow to dry over 24 hours, apply another layer, allow to dry and repeat the process until you have a thick enough coating to make a lasting mold.

3.) The professional mold maker will use gauze strips to reinforce the mold. By dipping a gauze strip into the liquid latex, you then apply to the mold. This is generally done on large objects and not smaller objects. 

The Picture below is an example of application style #1.  This is a project I will post later.


Once the you have applied enough latex layers to create a thick mold, you will need to remove the mold from the object.
1.) With a sharp exacto knife, score a cut deep along one side of the mold.  If the knife doesn't cut or cannot cut through the layers of latex, a pair of scissors may be used.
2.) Gently begin peeling  back the latex from the object. I do not coat my objects with anything, as the latex generally releases very easily. 

Keep in mind it may be necessary to peel the entire mold all the way back, as tho you are turning it inside out.

One you have removed the the latex from your oject, you will have a mold to create wax casts from. 

Stay tuned for the next section on how to pour the wax and prepare the wax object to be placed in plaster of paris.......