Customers purchased Thin Sheet Glass to use for computer screens and for screens on hand-held TVs. Complaints about lint and surface contaminants were a regular occurrence, but recently seemed to be on the increase.
The current process included a wash cycle for all sheets of glass prior to packing for shipment to the customer. How could the glass have surface contaminants? What is going on?
I facilitated a session to design an experiment to test the difference in contamination between washed and unwashed glass. This Experiment was done during a single shift. During the shift twenty sets of five sheets of glass were randomly selected to be washed or not. All 100 sheets of glass were carefully packaged and sent to the customer.
When the customer received the glass, they used all 100 sheets in production and kept careful notes on surface contamination for each sheet. Once the Glass Company received the data from the customer, the analysis gave results that were both clear and a shocking surprise. The unwashed glass was essentially free of lint and surface contaminants.
The washing process had introduced contaminants to the glass surface plus it made it more likely that the surface would attract lint. The Glass Company employees assumed that washing was a good idea, but discovered that assuming something doesn’t make it true.