What can go wrong when materials are fed into Cleanroom?

Especially "Cleanroom newcomers" often make simple, small but serious mistakes when introducing material, unfortunately often due to a lack of knowledge.

So what are the classic errors when introducing material into the Cleanroom?

Cardboard boxes or wooden pallets are taken into the airlock
Packaging is opened too early or uncleaned
Material is generally inadequately packaged.

In general, clothing, cleaning agents and materials used in Cleanroom are usually packaged several times. Paper and cardboard packaging in particular carry the risk of introducing large quantities of particles and dust, so cardboard packaging should be avoided in classified areas wherever possible and easy-to-clean containers and pallets with smooth surfaces should be used instead.

And when does which packaging have to be removed and how?

Remove external packaging that generates contamination, such as wood, cardboard or paper, before introducing it into the cleanroom areas. Care must be taken to ensure that the next outer plastic packaging is not damaged
Place the material in the outer plastic packaging in the first airlock. First wipe the top and then the sides with a suitable cleaning agent.
Tear open the outer layer of the packaging film, peel it off and dispose of it in a suitable waste container.
Repeat the cleaning process for each additional layer. Remove the last packaging before the material or object is used.