How does lost-wax casting work for silver jewelry?

ZKZ Editorial TeamMain answer · Product & gemmology desk

In lost-wax casting, a model is made in wax, surrounded by a heat-resistant mould, the wax is melted out and molten silver fills the space. After cooling, the mould is removed and the piece is cleaned, finished and polished.

The steps

Our advice The process has several stages, and each can affect the final quality.

1. Model: a master is carved or 3D printed, from which a mould and wax copies are made.
2. Tree: wax copies are attached to a central stem.
3. Investment: the tree is placed in a flask and covered with plaster-like material.
4. Burnout: the flask is heated so the wax melts and runs out.
5. Casting: molten silver is poured or forced into the empty mould.
6. Cooling and devesting: the mould is broken away.
7. Finishing: pieces are cut from the tree, filed, polished and often plated.

Where quality is decided

• Wax detail, which carries into the metal
• Temperature control during burnout and pouring
• Metal cleanliness and mixture
• Careful finishing that avoids removing detail

It depends Casting is one method among others. Some jewelry is stamped, hand-fabricated or 3D-printed directly, and each has its own strengths.

Typical issues

Our advice Small pits, shrinkage and rough surfaces can appear and are removed or reduced in finishing. Thin parts can be harder to fill.

What to ask

• How do you control burnout and casting temperature?
• How do you inspect cast pieces before finishing?

Why this matters to a buyer

Our advice Knowing the process helps you ask better questions. If a piece shows pits, the cause may be burnout or metal temperature. If detail is soft, the wax or the finishing may be at fault. Buyers who understand the steps can discuss problems with factories more precisely and judge whether the explanation they are given is believable.

Our advice Ask your factory which finishing steps follow casting, such as filing, polishing and plating, because finishing decides how smooth the surface looks and how consistent pieces are from batch to batch.

Uncertain We cannot describe any specific factory's process. Ask them to explain theirs.

Related reading: Casting or stamping: which suits small runs of silver jewelry? · What Does 925 Mean on Silver Jewelry?

Sources

No external standard governs this question, so this answer is editorial advice from the ZKZ team and is labelled that way.

Fact = stated by the cited source. Our advice = editorial recommendation. Uncertain / it depends = limits of what can be said in general.