Colored Frit
Crushed coloured glass graded by mesh size, rolled onto a hot gather for speckled colour.
Coloring
| Common oxides | Cobalt, copper, iron, manganese, chromium, nickel |
|---|---|
| Typical dosage | 0.5 - 5 percent by weight of batch |
| Effect on COE | Measurable, must be compensated in the recipe |
| Form | Fine powder, sometimes granular |
Compatible glass types
Soda-lime
Borosilicate
Lead crystal
Compatibility assumes the tool is rated for the working temperature of that glass family. Check the maker's documentation before use.
Overview
Metal oxides are the primary colourants behind every coloured glass. Cobalt gives deep blue at a fraction of a percent, copper gives turquoise or ruby depending on oxidation state, iron gives green and amber, manganese gives purple and is also used as a decolouriser. They are powerful in tiny quantities and they change the working properties of the glass, including its expansion.
Safety notes
- Cobalt and chromium compounds are hazardous by inhalation and some are suspected carcinogens. Use a respirator, gloves and extraction.
- Never handle oxides near food. Store in clearly labelled, sealed containers.
- Dispose of oxide waste as chemical waste, not in the general bin.
Using it well
Practical guidance
- Weigh oxides on a balance accurate to 0.01 g. A pinch is far too much for cobalt.
- Iron and manganese are cheap starting points for learning how oxides behave in a melt.
- Expect the expansion to shift. Recheck the annealing schedule after changing a colourant.
What to look for
- High tinting strength at very low dosage
- Documented effect on expansion for recipe adjustment
- Supplied in sealed containers with hazard labelling
Reference information only. Specifications are published ranges drawn from manufacturer documentation and normalised for comparison. They vary between makers and between individual units. This page does not sell or endorse any product, and does not guarantee any result. Follow the equipment manufacturer's instructions and take hands-on instruction before operating hot glass equipment.
Related
Tools used alongside the metal oxide
Glass Powder
Finely milled coloured glass, sifted or dusted onto hot glass for soft gradients.
Coloring
Gold Leaf
Transfer gold applied to hot glass, where it fuses into a metallic surface layer.
Coloring
Grinding Medium
Abrasive grit and carrier used to prepare or texture a glass surface before finishing.
Coloring
See the color & surface workflow
Read the category overview, or jump into the 3D Studio to see these tools applied to a live piece.