Empty cartridges: what weighing reveals and what it cannot
UpdatedStartoner · Ink and Measurement
A cartridge marked as empty may still hold ink. But weighing it alone does not tell you how much remains or how many pages you could still print.
HP documents the existence of residual ink, and Epson acknowledges that ink may remain when the replacement alert appears. The practical question is what that residue means and what a scale actually proves. HP manual, «Ink usage» section [1] and Epson documentation on ink yield [2].
Document review: 2 October 2026. We did not weigh cartridges or perform physical lab testing. This article provides an explanation and an original protocol for recording future measurements.
Conceptual illustration generated with AI. It does not represent an executed test or measured results.
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«Empty» can mean different things
It is essential to separate the printer message, the amount of material inside the cartridge, and the practical ability to keep printing. An alert is not a mass reading. Nor is 'low ink' identical to a mandatory replacement command: write down the exact screen text before drawing conclusions.
In its support documentation, HP distinguishes printer families that permit certain bypass methods from those requiring ink in all cartridges [3]. A workaround that works on one printer cannot be assumed for another. Here we focus on ink cartridges and their measurements; laser warnings are covered in our guide on the «toner exhausted» message.
| Concept | What it means here |
|---|---|
| Operational stop | The machine prompts to replace the cartridge or ceases printing, according to its displayed alert. |
| Residual ink | Ink material remaining inside the cartridge at that moment. |
| Usable ink | The ink the system can draw and print correctly under specified operating conditions. |
These definitions avoid a common mistake: proving that physical material remains does not prove that extra pages could have been printed without damaging the printhead.
What HP, Epson, and Canon actually explain
HP: the Officejet Pro 8640/8660 manual identifies uses of ink during preparation and maintenance, and states that residual ink remains after the cartridge has been used. It does not give a universal proportion. Source: HP, page 3 [1].
Epson: its documentation states that the amount remaining after the replacement message varies. In its support information for the SureColor P6570E, it also explains that introducing air into the system when there is no ink left can damage the permanent printhead. This is an explanation of that system, not a measurement of your cartridge. Source: Epson, consumables [2] and FAQ on remaining ink [4].
Canon: the PIXMA TS6300 manual explains that cleaning consumes ink and that automatic cleaning starts after an ink tank is replaced. This information matters when interpreting a weighing before use and another after use. Source: Canon, replacing ink tanks [5].
The sources support discussing residual ink and additional ink consumption. They do not allow us to state how much remains in all cartridges, compare original cartridges with compatible ones, or accuse a brand on the basis of a single case. A compatible cartridge needs its own identification and measurement; a tare value from another manufacturer cannot be transferred without validation.
The trap: weighing plastic counts too
A scale measures the entire assembly: housing, components, ink, and any accessories present. To estimate residual ink, you would need to know the mass of the same assembly without ink, with equivalent components and moisture condition. That reference is the cartridge tare mass. Zeroing the scale with a tray removes only the tray, not the cartridge’s plastic. NIST: gross, net, and tare weight [6].
Estimated residual ink = mass at stop − validated cartridge tare
This is a mass balance relationship, conditional on having controlled the other contributions. A used cartridge bought as “empty” does not constitute a verified tare. Nor is a table sufficient without an exact reference, method, and variability. Even two units of the same model may require an assessment of manufacturing differences.
Drying or washing a spent cartridge does not easily provide an accurate tare. Drying can leave pigments and resin deposits; washing can introduce moisture, dissolve lubricants, or alter plastics. Establishing a true tare requires laboratory-grade validation. We do not recommend opening, drilling, or flushing cartridges at home.
If you have an initial weight of the exact same cartridge before installation and another upon removal, you can calculate the total mass loss:
Assembly mass decrease = initial mass − final mass
That difference is not residual ink, nor does it identify on its own how much reached the paper. It may include ink used for maintenance or to fill conduits, evaporation, and losses during handling. Epson also documents evaporation under prolonged exposure to extreme conditions. That possibility requires controlling the environment, not assigning a fixed loss. Epson: ink consumption and yields [7].
A protocol you can repeat without opening anything
The goal of basic recording is to log the printer status message and total mass of an intact cartridge. Compare initial and final weights only if both were captured according to the manual without leaving the printhead exposed. This is not an accredited certification or a bypass technique.
- Define the sample. Record printer model, full cartridge SKU, colour, standard or XL capacity, manufacturer, batch number if visible, and dates. Distinguish starter cartridges from replacement units.
- Prepare the measurement sheet. Note the scale model, resolution, verification with a reference calibration mass, and ambient temperature/humidity. Decide beforehand the maximum time out of the printer and protective cap status, aligned with the user manual.
- Record initial weight only if viable. Weigh before installation, including all caps or seals that will also be present during the final weighing. Never compare a sealed, boxed cartridge to an unpacked one. If comparability is broken, omit the difference.
- Document usage. Keep a log of printed files, quality settings, paper types, page counts, idle intervals, and cleaning cycles. Note 'unknown' whenever an automatic maintenance cycle occurs unobserved.
- Respect the endpoint. Take a photograph of the replacement alert on screen. Have the replacement cartridge ready and follow the manufacturer's manual. Do not force continued printing to make the cartridge 'more empty'.
- Weigh and repeat. In each proposed session, take three readings, removing and repositioning the assembly. This is an initial repeatability check, not a test of three cartridges or a complete uncertainty assessment. Note the time and any leaks.
- Preserve raw records. Keep all readings, photos, and notes, including unexpected values. If no validated tare exists, mark residual ink as 'undetermined'.
The manufacturer’s procedure takes precedence: Canon asks users to replace the removed ink tank immediately and not leave it exposed outside the printer. If your weighings prevent compliance, record only the cartridge that has already been removed and do not calculate consumption between the initial and final measurements. Canon TS6300 precautions [5].
Controls: how to avoid false conclusions
A reference mass helps detect scale drift. A second comparable cartridge that is not used for printing, under documented storage and handling conditions, may help explore changes unrelated to printing. However, it does not reproduce a printer’s heat, ventilation, or cycles: do not subtract its mass loss as an exact evaporation correction.
Distinguish scale display resolution from measurement uncertainty. Screen decimal places do not guarantee accuracy. Repeatability, linearity, thermal drift, drafts, and tare uncertainty all contribute. NIST notes that uncertainty belongs to the result and depends on the complete setup. NIST: uncertainty approach [8].
When subtracting initial and final mass, combine the uncertainties of both measurements and account for correlated errors, such as using the same scale. A simple root-sum-square assumes independence; correlated components require proper covariance terms. NIST: propagation of uncertainty and covariance [9].
If the calculated residual mass is within the measurement uncertainty, the data cannot confirm that residue exists. A negative calculated mass indicates flawed baseline values, uncorrected drift, or invalid tare assumptions. Without an uncertainty budget, present figures as preliminary observations.
What conclusions each record allows
| What you recorded | What you can communicate |
|---|---|
| A single weight when the alert appears | Total observed mass and exact message, with residual ink undetermined. |
| Comparable initial and final mass of same cartridge | Total mass loss of the unit, without attributing it entirely to printed pages. |
| Final mass, validated tare, and uncertainty budget | Estimated residual ink within stated experimental conditions and limits. |
| Initial validated ink mass added to the above | Estimated residual mass percentage, with stated uncertainty and explicit denominator. |
Do not divide residual mass by total cartridge weight to calculate an 'ink percentage'. Nor should you convert grams to millilitres without measuring ink density at operating temperature. Translating grams into page counts requires a standardized yield test; our guide on cartridge yield and pages per cartridge addresses that question.
Download the log sheet and decide with better evidence
Original documentation, without pre-filled data: printable A4 protocol and observation sheet, blank measurement CSV and data dictionary and field instructions · Spanish documentation (ZIP).
The PDF includes a planning form, a sheet for readings, and criteria for interpreting the result. The CSV contains only headers: each future data point must come from an identifiable observation. Print one sheet per cartridge and session; record each control separately.
If your immediate problem is that the printer will not print, start from the alert screen and consult troubleshooting when ink is present but nothing prints. When it is time to replace the cartridge, check compatibility in our section on compatible ink cartridges. For cartridge disposal, see where to recycle ink and toner cartridges.
A solid conclusion can be modest: 'this cartridge weighed X grams when this alert appeared'. Without a validated tare and controls, asserting 'therefore Y ml of usable ink was wasted' claims knowledge your scale did not measure.
Sources and references
- HP manual, «Ink usage» section
- Epson documentation on ink yield
- HP distinguishes printer families that permit certain bypass methods from those requiring ink in all cartridges
- FAQ on remaining ink
- Source: Canon, replacing ink tanks
- NIST: gross, net, and tare weight
- Epson: ink consumption and yields
- NIST: uncertainty approach
- NIST: propagation of uncertainty and covariance
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