Lightweighting Plastic Packaging and Recyclability Dr Michael Scriba, CEO mtm plastics, Niedergebra (Germany) It is more or less common knowledge that in lightweight design fully functional mono-materials are replaced by multilayers with one or two polymers different from the main material partly replacing mono-material and, with better barrier properties in thinner layers, reducing the overall weight of a pack. Consequently fully functional rigid packagings (bottles) are reduced in weight to a considerable degree. They will even become flexible packs (pouches), and films are reduced in thickness etc. without losses in functionality. Lightweighting as a concept is enormously widespread and has considerably reduced the amount of virgin plastics used in packaging over the last decades. But there is a downside to this: Packers and fillers like to call this aspect resource efficient and use it as an excuse when it come to recyclability. The worldwide trend is evident but causes a lot of problems for sorters and recyclers: In state-of-the–art optical sorting factories (MRFs, PRFs) multilayer materials create random sorting results as the light beam will possibly penetrate one or two outer layers before it is reflected to be analyzed by the machine. The same is true in ballistic sorting because the ballistic properties of a flake become the more random the lighter it is, and in density separation altered specific weight of a formerly monopolymer results in bad yields. If a mulitlayer strucuture (randomly) ends up in the targeted polymer stream in recycling, its non-targeted components or polymers will always contaminate the recycled product. Reduced mechanical properties, discolouring, odours etc. etc. will have a negative impact on prices and the product will have difficulties to meet the high standards of plastic converters for their recycled feedstock. Something we often forget to mention: These effects are worsened by the ties needed to combine different layers. What I would like to challenge today is the argument that this deplorable situation is formally justified by the waste hierarchy „Reduce, Reuse, Recycle". There seems to be a common – and possibly wrong – understanding amongst packers and fillers that reducing the weight of a package is so resource-efficient that its recyclability can be neglected, and only so because „reducing" is located on a higher level than „recycling". Hence weight reduction seems to have become an end in itself. But is this correct? Reducing at the cost of recyclability means that