# Dirty eggs: what counts as dirty and where they go > A dirty egg has an unbroken shell with adhering dirt or foreign material, such as faeces, blood, soil or yolk. It cannot be Class A, which requires a clean shell. In Brazil, washing is mandatory for dirty, uncracked eggs sent to processing, and eggs that are both dirty and cracked are discarded. In the European Union, Class A eggs must not be washed. Updated: 2026-10-09 · URL: https://vigiovo.com/en/resources/dirty-egg-grading · Português: https://vigiovo.com/recursos/ovos-sujos-classificacao.md ## Key takeaways - A clean shell is a requirement for Class A in Brazil (RIISPOA, art. 225) and in the European Union. - In Brazil a dirty uncracked egg can go to processing, with mandatory washing (MAPA Ordinance 612/2022, art. 18). - A dirty cracked egg has no use as human food and must be discarded. - Measuring dirt in an image means comparing each stain with that egg's own shading, not with a fixed brightness. ## What is a dirty egg? A [dirty egg](https://vigiovo.com/en/resources/glossary#dirty-egg) has a whole, uncracked shell with dirt or foreign material stuck to it. The US definition is direct: a dirty egg has an unbroken shell with adhering dirt or foreign material (7 CFR 57.1). The usual culprits on a farm are faeces, blood, soil, stuck feathers and yolk from another broken egg. Brazil's RIISPOA treats dirt as both a quality and a safety criterion: Class A requires a "clean" shell (art. 225), and eggs with external faecal dirt are unfit for human consumption as they are (art. 500). ## Can a dirty egg be washed? It depends on the destination and the country. In Brazil, MAPA Ordinance 612/2022 defines washing as the step that sanitises eggs and makes it mandatory for dirty, uncracked eggs going to industrial processing (art. 18, as stated in MAPA's question-and-answer guide). Dirty cracked eggs may be neither washed nor used in egg products (RIISPOA, art. 228). MAPA is explicit: they have no use at all as human food and must be discarded immediately at the establishment. In the European Union the table-egg rule is the opposite: Class A eggs shall not be washed or cleaned, before or after grading, except as provided for (Delegated Regulation (EU) 2023/2465, art. 4). Washing can strip the [cuticle](https://vigiovo.com/en/resources/glossary#cuticle), which helps protect the shell's pores. **Where a dirty egg goes** | Situation | Brazil | European Union | | --- | --- | --- | | Dirty, not cracked | Not Class A; processing with mandatory washing | Not Class A; Class A cannot be washed | | Dirty and cracked | Discarded immediately; banned from egg products | Not Class A | | Clean, not cracked | Can be Class A if it meets the other requirements | Can be Class A | ## What is the difference between dirt, stains and natural shell colour? Not every dark patch on a shell is dirt. Shell colour varies from egg to egg and even within one egg, and the egg's dome creates a natural brightness gradient under any light. A grader, human or automatic, has to tell three things apart: - **Adhering dirt**: material on the shell (faeces, soil, blood, yolk), usually a different colour from the shell with an irregular edge. - **Natural variation**: speckles and tones of the shell itself, which are not a defect. - **Lighting effects**: highlights and shadows from the dome, which change with the position of the egg and the lamp. ## How do you measure shell dirt with a camera? Comparing each pixel with a fixed brightness fails, because the rim of a clean egg is naturally darker than its centre. Vigiovo fits a quadratic [shading surface](https://vigiovo.com/en/resources/glossary#shading-surface) to each egg and measures only what falls well below it, so every stain is measured against its own egg. In parallel it measures colour deviation in [Lab colour space](https://vigiovo.com/en/resources/glossary#lab-colour-space), which catches stains as bright as the shell but a different colour, and it discards specular highlights. If the stains add up to 3% or more of the visible shell, the egg is graded dirty. That limit is a Vigiovo configuration value, calibrated with labelled eggs from each line, not a legal standard. ## How do you reduce the number of dirty eggs? Grading removes dirty eggs, but the cause is in the house. The factors that matter most: - frequent collection, so eggs spend less time in the nest or cage; - clean, dry nests and litter; - maintained collection belts, to avoid broken eggs smearing their neighbours with yolk; - tracking the dirty-egg rate per house and per day, which shows early when something changed. A system that records the class of every egg, like Vigiovo, turns that last point into a daily number with no extra work. ## Frequently asked questions ### Can dirty eggs be sold? Not as Class A, which requires a clean shell. In Brazil a dirty uncracked egg can go to industrial processing, with mandatory washing. A dirty cracked egg must be discarded. ### Can you wash dirty eggs to sell them as Class A? Brazilian rules treat washing as a processing step (MAPA Ordinance 612/2022, art. 18). In the European Union, Class A eggs shall not be washed or cleaned, before or after grading (Delegated Regulation (EU) 2023/2465, art. 4). ### What percentage of dirt makes an egg dirty? The regulations cited here don't set a percentage: they require a clean shell for Class A. Automatic graders use a configurable limit. Vigiovo's default is 3% of the visible shell, tuned when each line is calibrated. ## Sources - [Decreto nº 9.013/2017 (RIISPOA)](https://www.planalto.gov.br/ccivil_03/_ato2015-2018/2017/decreto/d9013.htm), Presidência da República (Brasil) - [Perguntas e respostas sobre a Portaria MAPA nº 612/2022 (versão de 05/06/2023)](https://wikisda.agricultura.gov.br/manual_ovos/perguntas_e_respostas_port612_2023.pdf), Ministério da Agricultura e Pecuária (MAPA) - [Delegated Regulation (EU) 2023/2465, marketing standards for eggs](https://eur-lex.europa.eu/eli/reg_del/2023/2465/oj/eng), EUR-Lex - [7 CFR § 57.1 Definitions (Inspection of Eggs)](https://www.ecfr.gov/current/title-7/subtitle-B/chapter-I/subchapter-C/part-57/subpart-A/section-57.1), U.S. Electronic Code of Federal Regulations ## Read next - [How to identify cracked eggs: types, methods and rules](https://vigiovo.com/en/resources/how-to-identify-cracked-eggs.md) (Guide, 2026-10-09): What a cracked egg (check) is, how it differs from a leaker, which methods detect each kind of crack and where cracked eggs must go under the regulations. - [Candling vs computer vision: what each one detects](https://vigiovo.com/en/resources/candling-vs-computer-vision.md) (Comparison, 2026-10-09): Candling compared with camera inspection in egg grading: which defects each detects, speed, record keeping and why the two methods work best together. ## How Vigiovo helps Vigiovo grades eggs on the conveyor as clean, dirty, cracked or unverified, in real time, with deterministic computer vision: every decision comes with the measurements behind it, on an ordinary CPU. https://vigiovo.com/en/how-it-works.md 4 min read.