feedstock: negative sort
Need help? Want more information? Get in touch now or phone +44 (0) 1324 489182

What is negative sort/unseen?

The negative sort, or unseen material from optical lines was a key driver in the original development of BOSS.  The unseen material is called, as it is what has been missed by the optical sorters in operation.  This is because in most cases they struggle to see ‘black’ material and therefore approximately 25 – 30% of a mixed bale will end up in a mixed plastic.

Impact have analysed many of these samples with the mixed polyolefin content of this material being between 60% and 70%.  This represents a good feedstock for BOSS and a high value use of an otherwise negative value plastic.

unseen plastic

BOSS output

PP rich – 90% upwards.  This depends on the setting chosen and the end market.  Material MFR’s depend on the feed stock being processed through the optical line

PE rich – 90% upwards, with the only contamination being PP.  Again, final properties depend on the material being run through the optical plant.

Sink fraction – typically a large mix of polymers, with PVC, ABS and PS in abundance.  Further processing can separate out the ABS and PS using density solutions if required.


A good, high value use of BOSS and an excellent way to get more value out of your existing optical sorting plant.

example feedstock

feedstock: automotive

latest plastic testing blogs