Effetre Millefiori Cabochon Firing Guide

Create your own mosaic inclusions or jewellery! Mosaico has published a cabochon firing guide for COE104 Effetre Millefiori. Photos are included as a guide for each step.

1. Prepare the kiln shelves using either method (a) OR (b). SAFETY PRECAUTION: Kiln wash and kiln paper are toxic. Wear a mask and handle with care, and wash hands and any spillages directly after use.

(a) Prepare the kiln shelves with kiln wash, mixing the wash according to package instructions. Brush the first layer onto each shelf, dry, then apply second coat at 90-degree angle to the first coat. Repeat until 5 coats have been applied. Load the shelves into the kiln and heat to 260°C. As this step is to evaporate moisture, remove plugs and have the lid/door slightly ajar.

(b) Alternately, line the shelves with kiln paper, cut to size. Use offcuts to save on cost.

2. Fill the shelves with small glass pieces. To prevent cracking, always use the same expansion rate (e.g. COE104) when combining glass sheet, rod, frit, or millefiori. Fired cabochons are approx. 5mm thick, therefore allow more space around unfired pieces > 5mm. thick.

Most kilns are cooler at the bottom; use the bottom shelf for smaller pieces and reactive colours e.g. Avorio, Verde Pet., Turchese, to prevent firing metallic. Alternately, use less shelves and raise the bottom shelf.

Load the kiln and put in plugs.

3. SAFETY PRECAUTION: Kiln gas emissions are toxic; wear a mask and ventilate the room. Before firing, check that you can view some pieces through the peephole. Set the firing schedule to:

  • Ramp 1 at 315°C (per hour)
  • Fire to 635°C
  • Hold 30 mins
  • Ramp 2 at 315°C
  • Fire to 820°C

At 750°C view at a distance through the peephole. The pieces should start ‘balling up’. Keep checking every few minutes until the top is domed but the base and sides of the ‘ball’ flatten and the kiln is just starting to cloud over. The kiln temp will be approx. 800°C (will vary between kilns). Don’t hold the temp. (helps keep millefiori patterns intact).Turn the kiln off.

4. Flash cool to 550°C by removing plugs and carefully opening and closing the lid/door slightly. The temperature can be checked by turning power on then off. Plug up and close the door for 30mins to anneal.

5. Allow the kiln to cool to room temperature. The door can be opened slightly during this time to view, then close.

6. SAFETY PRECAUTION: Wear a mask during unloading of kiln, cleaning, and disposal of waste. Unload cabochons from the kiln, wash with water and dry. Dispose of kiln paper and wet waste wrapped in the rubbish, not down the drain.

SAFETY PRECAUTIONS: Glass firing emissions, kiln gas emissions, and kiln firing products are known toxins and carcinogens. Refer to the safety guidelines from the manufacturer of individual kilns and products for specific precautions and hazards. Please note: these instructions are a guide only, based on the kiln used by Mosaico. Results may vary and outcomes are not guaranteed.