I was hoping experts in this forum could help me out here. I have experience in automotive quality, where we dealt with components/parts that could be physically measured. So how do you apply the same quality control concept in a chemical industry, specifically polyurethane (raw material)? Our products are supplied in 2 parts of chemical (1 is Isocyanate, the other is a blend of polyols and additives). All we do in house is blend certain chemicals and supply them to our customer. So basically, we won't be able to see the final product until it gets to the customers' production line where the chemical reactions occur. Quality checks measure a few reaction timing from a sample foaming test in the lab. Does it even make sense to apply SPC to lab-measured attributes such as water%, reaction profiles (very subjective in measuring time), when the product itself is so sensitive to environmental elements (temp., humidity, etc.)? How do you even measure process capability in this case? What methods could be used for quality control? Any feedback would be greatly appreciated! Thanks in advance!