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The Lost Wax Casting Process
Wax: An Overview
Ceramic Slurry Dipping Schedule
The Sandcasting Process
The Chasing Process
Methods for Joining Bronze
Patinas
Investment Casting: 1930-1950
Project #2: Sandcasting a Bas Relief Bronze Plaque
How to Build a Bronze Casting Furnace
Foundry Safety
Furnace Lighting Procedure
Project #1: Direct Wax Sculpture, Ceramic Shell Casting

Wax: an Overview

Traditionally, various formulations of beeswax were used by sculptors to make waxes of varying hardness. With the production of synthetics such as microcrystalline and paraffin wax, the use of beeswax is much less popular. Microcrystalline wax is the most commonly used sculpting wax by artists today.

Microcrystalline wax comes in many colors, but bronze sculptors commonly use a brown wax because it helps the artist visualize the finished product. Victory brown is a common example of this. It has a melting point of about 175° when slightly warmed it is soft enough to model with by hand.

The addition of petroleum jelly to melted wax will soften it, and paraffin or rosin can be added to harden it. Generally the harder and less pliable a wax, the higher the melting point will be.

Types of wax:

There are many types of waxes available. Most of them are synthetic and come in a variety of hardness and pliability. Here are a few of the most common used for sculpting.

Natural Wax

o Beeswax: A fragrant, pliable, soft, and somewhat sticky wax produced by bees. The melting point and hardness is dependent somewhat on what flowers the bees collect pollen from. Melting point 142°-150°F.

Synthetic Waxes

o Microcrystalline wax: A pliable, medium-soft, slightly sticky wax. It is a synthetic wax derived from the petroleum industry. It has a smaller crystal structure then beeswax or paraffin (thus the name). This is the most common wax used by sculptors. Melting point is approximately 160°F.

o Paraffin wax: A white, slick, somewhat hard wax with a large crystalline structure. It is a synthetic derived from the petroleum industry. This wax is commonly used in candles and easily obtained from hobby stores. It is not good for modeling directly by hand, but can be used as an additive to microcrystalline wax or beeswax to make it harder. Melting point 135°-140°F.

•Specialty waxes:

Carving wax: A very hard wax that can be carved by hand with files, knife, scrapers, or with power tools such as a Dremmel or flex-shaft tool with rotary files.

Modeling Wax: A wax that easily softens by the heat of your hands. It is suitable for modeling much the same way you would work clay. Traditional modeling wax has a low melting point (around 125°F) but newer synthetics can have higher melting points.

Sticky wax: a hard wax that when warm is very sticky, and when hot is fluid. This wax is used to attach wax pieces, sprues, gates, etc. together. It is much like hot glue, but is a temporary connection for larger pieces and sprues that need to then be welded on.

Patch wax: A very soft wax used to fill in pinholes and small imperfections.

Pouring or Casting wax: Often red, this is a harder wax and more brittle wax used to pour into molds.

Shapes: Wax also comes pre-made in a variety of shapes and hardness.

Creating a sculpture directly in wax

Wax can be built up or applied in a variety of ways. Any method that gives the desired result in the final casting is the right way. Sculptors can use any or all of the techniques below to create a sculpture.

Hand-built solid sculptures

The earliest bronze sculptures were made this way. Beeswax was worked directly by hand to make small figures that could then be cast solid. The disadvantage to this is that a solid casting should not be more then about 1” thick. To go thicker then this would cause problems when cast in bronze and the thick portions of the metal could shrink causing porosity or a caved in spot (shrinkage) on the casting.

A larger hand-built sculpture could be made, cut in half, hollowed out, and then reassembled. This is a difficult and clumsy way to make a sculpture, but can useful for a piece that is a simple shape.

Use of a core

A clay or investment core the approximate shape of the finished work can be made and covered in a layer of wax either by painting, dipping or applying sheets of wax. The outside is invested and the wax burnt out. This was developed to a high art by the Greeks and Romans to make the first life size statues. A modern variant that is applicable to our class is to make a core using Styrofoam. Once the wax is built on it and chased (finished), the core can be dissolved with acetone, and the remaining wax can be invested and cast.

Use of wax sheets and cast forms

A sculpture can be built using wax sheets that are assembled into the final product. If the sculpture is too big to support itself, sheets or bars of wax can be placed inside to increase structural integrity. Shapes can also be cast in plaster (for example a half sphere from a ball) and cast in wax and then cut, reassembled, or added as is to the sculpture.

Direct modeling

Softer wax, such as microcrystalline wax, can be applied just like clay using small lumps of wax. The wax can be warmed to soften it by putting it near a light-bulb, in warm water, in the sun, or running a torch lightly over the surface and scraping off the warmed wax. Melted wax can be painted on, and if allowed to cool until it is just solid it can be applied like cake icing with a small or large spatula.

Carving

By using harder carving waxes, tools like a Dremmel as well as files, saws and other hand tools can be used to carve out a piece. In industry this type of wax can be machined on a mill or CMC machine. Softer wax can be cooled in the refrigerator to make it easier to work with hand carving tools.

Equipment for working with wax at home

Working with wax takes only a small investment, as the equipment is cheap and easy to acquire. Set aside a place that you don’t mind getting wax all over. It's messy, so the kitchen is not a good idea unless you like constantly scraping wax off of the stove, floor, and table.

Tools for modeling in wax

Clay working tools.

Metal tools. Either purchased or made from flattening the end of 3/16” wire and filing it to shape.

Hot knife. Either heating up a metal tool over a flame, or made from soldering iron or wood burning tool and a dimmer switch.

Some heat source. An alcohol lamp works fine. Other options: a small propane or gasoline camping stove, Bunsen burner (if gas is available).

Tools for pouring wax into plaster molds

A slow cooker or deep fat frying pot: This is for melting the wax in and would be used mostly if you are pouring wax into plaster molds, but may be used to melt large amounts for making flat sheets or melted wax to paint on or build up a piece. This can be obtained at any department store, mega-mart or at a second hand store. Be sure you get one with a thermostat. A good one is available at Sears or Walmart called the Presto Multi cooker - about $25-30.

A standard cooking thermometer from a market. It should read temperatures from room temperature to about 400°F.

A small one-quart saucepan for dipping out the melted wax to pour in moulds.

A paintbrush with natural bristles (the cheap disposable ones are ok, but watch for bristles falling out).

Helpful Links

Techniques and Information

David Reid, Waxes and Waxworking: An article that gives some ideas on waxes and techniques to work with them.

o http://home.c2i.net/metaphor/bkwaxworking.html

Suppliers

Arizona Sculpture.com: A good source of wax and sculpture tools. Larger selection then Sculpture Depot, but compare for prices and shipping.

o http://arizonasculpture.com/products.asp?page=2&catID=4&subcatID=

Sculpture Depot: Located in Colorado, a good source of supplies for the sculptor. Good variety of waxes and wax tools. Prices seem fair. Also a supplier of alginate (this is what we are using in class).

o http://www.sculpture-depot.com/html/wax.htm

Douglas & Sturgess, Inc.: San Francisco based supplier of all artist materials. Very comprehensive catalogue, especially for mold supplies and odd materials. This is one to check out and browse through!

o http://www.artstuf.com/DStockNEW.fm$FIND?catsearch=WAX&header=CatHead&footer=CatFoot&html=CatShelf&sort=SKU

Alec Tiranti Ltd: Supplier in the UK, but good list of waxes and information on them.

o http://www.tiranti.co.uk/subdivision_product_list.asp?Content=Waxes&Subcategory=43&Subdivision=

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Dan@RotblattSculpture.com
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