New Zealand Woolscouring Ltd has released statistics covering July 2019 to June 2020, on contamination and what they found in wool bales.
There were 724 incidents of contamination in bales in the North Island, compared with 159 in the South Island.
That included plastic, cardboard, stock feed and fertiliser bags, press bars, shearing combs, hooks, wire, rubber, clothing, glass, rubbish and spray cans.
The lower figures in the South could be because wool classers were used more in southern sheds than in the North Island, NZW chief operating officer Tony Cunningham said.
"We are seeing more care and attention in wool sheds where woolclassers are operating.
"It is a big tick to the New Zealand Wool Classers Association members.
"The wool classers set up and control the sheds and are doing a great job."
NZW offered incentives to North Island wool handlers to encourage them to capture contaminants before they left the sheds.
"If contamination goes through the scouring process, then machinery repairs and lost production could be quite a big cost to the company.
"We are pretty good at detecting metal but non-metal product is a big issue. The risk of having plastic imbedded in carpet is a big risk."
He has seen clothing, including hoodies and moccasins, going through.
"I have found an intact $10 note, full bottles of beer and a clock that stopped at 10am, so it must have fallen in the bale at smoko time."
NZWCA executive officer Bruce Abbott, of Mosgiel, said the care by wool classers, as well as training shed staff, had a big influence on what happened in southern sheds.
A few years ago he found a complete pay packet in a bale.
"Last year somebody grabbed a sample out of bale and pulled out a towel."
