This study identifies hidden artefacts in a public organisation. In contrast to earlier studies, it focuses on artefacts as concealing rather than conveying meaning. Negligent behaviour caused by an unpopular culture was recognised in five psychiatric wards at a Swedish university hospital. Data comprising observations (87 h) and interviews (n = 60) were collected over a period of 48 months (2008-2011). Four different items used in everyday work representing a deeper meaning of the organisation were identified during the observations. The items selected were work attire, nametags, keys and restraint beds. These were considered particularly promising when it came to the aim of the study, namely, to find out how artefacts are camouflaged. The observations and the interviews revealed that these were controversial and contested artefacts in the organisation. The study uses the term 'cultural camouflage' for behaviour that ignores and consciously conceals symbols that have negative values. This concept contrasts with previous research that shows how artefacts are emphasised and how they contribute to the character of the activity in a transparent way. Conservative and backward-looking behaviour among staff provided one explanation as to why artefacts were concealed. Another was the need to establish harmonious internal interactions.