Common Enamel Firing Problems and How to Fix Them

When your enamel jewelry doesn’t come out of the kiln looking as expected, there are usually clear reasons—and often ways to fix or avoid the problem. Below is a guide to common enameling issues, their likely causes, and troubleshooting steps to help you improve your firing results.

Problem: Green Stains or Blemishes on Enamel (Especially on Copper)

Likely Cause: Either your layer of enamel that was fused was applied too thinly, or the firing was too long or too hot, resulting in formation of cupric oxide that tinted the enamel.

Can it Be Fixed? Unfortunately, this is irreversible. You can attempt to cover the blemish with another layer of enamel. 

Problem: Black Dots on Enamel Surface

Likely Cause: Black specks are most often the result of firescale flakes from exposed copper edges or from steel trivets.

How to Fix:

• Gently remove black particles with a diamond point tool
• Scrub with a glass brush under running water
• Apply more enamel if needed and re-fire
• To prevent this, sand away firescale from edges between firings

Problem: Bare Spots or Oxidized Holes After Firing

Likely Cause: Improper drying before firing. If the enamel is placed in the kiln with moisture, the moisture will evaporate rapidly, causing enamel to bubble and fall off.

Another possibility is that the enamel was applied too thinly or left in the kiln too long, causing the enamel to burn out in places.

How to Fix: Clean the oxidized parts with an abrasive, or pickle the piece. If you pickle, rinse very thoroughly. Once the oxidation has been removed from the bare patches or holes, add more enamel into the exposed areas and re-fire.

Problem: Cloudy or Milky Transparent Enamel (Especially Flux)

Likely Cause:

• Enamel was unwashed before application
• Under-firing of transparent enamel

How to Fix: Always wash or size transparent enamels before applying. Unwashed enamel cannot be fired to increase transparency.

It is typical for flux to appear cloudy if it is under-fired; so if you washed your enamel prior to applying it and it looks cloudy, this was likely the result of insufficient firing. The piece may be returned to the kiln for a longer time or at a hotter temp and re-fired until it is nice and clear.

Problem: Enamel Pulling Away or Peeling Off Edges

Likely Cause:

• Firing temperature was too high
• Metal was dirty or greasy
• Enamel layer was applied too thickly

How to Fix:

• Sand or stone back thick enamel
• Clean metal edges until they are bright and free from oxides
• Rinse thoroughly and wash with a glass brush. Reapply enamel to bare spots before re-firing

Problem: Cracks or Chipped Enamel After Cooling

Likely Cause:

• Uneven application of counter enamel
• Incompatible counter enamel formulations

How to Fix:

• If back enamel is too thick, stone it down
• If too thin, apply a new layer to balance internal tension
• Re-fire to stabilize enamel across both sides of enamel and counter enamel

Problem: Orange Peel Texture on Enamel Surface

Likely Cause:

• Enamel was under-fired or kiln temperature was too low.

How to Fix:

• Re-fire the piece until the surface becomes smooth and glossy
• Consider increasing kiln temperature for improved results