Toner
Definition
A dry-powder printing material consisting of fine styrene-acrylate polymer particles carrying carbon black and organic pigment, electrostatically applied and thermally fused at 180-200°C. Distinguished from all liquid inks by its surface-layer deposition and polymer chemistry.
- Material
- Fine styrene-acrylate polymer particles
- Colourant
- Carbon black plus organic pigment
- Application
- Electrostatic deposition
- Fusing
- Thermal fusion at roughly 180-200°C
Common questions
How is toner distinguished from liquid ink under examination?+
Toner sits as a fused polymer layer on top of the paper surface rather than penetrating the fibres, so it can be seen under magnification as a raised, glossy deposit, and it lacks the capillary feathering or solvent-driven spread characteristic of liquid inks.
Why does the fusing temperature matter forensically?+
The heat needed to fuse toner can be relevant when documents are examined for alteration, since re-fusing toner over an existing printed area, or laser-printing onto a document that already carries other marks, leaves detectable heat-affected changes in the surrounding paper or prior toner layer.
Can toner chemistry identify the printer that produced a document?+
Toner formulation varies by manufacturer and cartridge, so elemental and polymer analysis can narrow the source to a class of printers or cartridges, but it identifies a class match rather than a single unique device without corroborating physical evidence such as drum defects.
Related terms
- ASTM E2285 / E2286
- The two ASTM International standards governing forensic ink examination: E2285 covers TLC-based ink alteration examination; E2286 covers HPLC-based ink comparison. Both are...
- Ballpoint Ink
- An oil-based, high-viscosity ink using a resin binder (alkyd or polyamide) in a high-boiling solvent (phenoxyethanol or benzyl alcohol), with triphenylmethane dyes...
- HPLC-DAD
- High-performance liquid chromatography with diode-array detection. Separates ink dyes on a C18 column and records UV-visible spectra at each elution point, providing...
- Iron-Gall Ink
- A historical ink formulation of ferrous sulphate, tannic acid (from oak galls), and gum arabic. The ferrous-tannate complex oxidises to brown ferric-tannate...
- Phenoxyethanol
- The primary high-boiling solvent in most modern ballpoint ink formulations. Its progressive evaporation from the dried ink film after writing is the...
- Raman Microspectroscopy
- A vibrational spectroscopy technique using a focused laser beam to excite molecular vibrations in an ink sample. Non-destructive. Primary method for toner...
- TLC (Thin-Layer Chromatography)
- A planar chromatography technique on silica gel plates that separates ink dye mixtures by polarity. ASTM E2285 governs its forensic application. The...
- USSS International Ink Library
- A collection of ~10,000 dated writing ink formulations maintained by the United States Secret Service since 1968, providing a terminus post quem...
- VSC (Video Spectral Comparator)
- A multispectral imaging instrument used in document examination; illuminates the document at multiple wavelengths (UV, visible, near-IR, IR) and captures fluorescence and...