Microscopy as an analytical tool for paper industry.

IM (Industrial Microbiologist) has worked as a microscopy teacher and trainer for paper industry since the beginning of 80's. It seems that this analytical tool is very popular: annual courses in Helsinki and at the customers' facilities have indicated an everlasting need to achieve training and experience in microscopy.

There are three major areas of paper industry where microscopy can serve as a rapid tool for analytical control:

• Raw material, process and product microbiology. Traditional Bright Field, Dark Field and Phase Contrast microscopy are always valuable methods. Epifluorescence microscopy techniques (Confocal microscopy included) help significantly when biofilm studies with test coupons will be performed.
• Fibre microscopy. Bright Field microscopy of stained fibre preparates is a common method for the investigations of fibre contents of paper and board.
• Activated sludge microscopy. This is the fastest and most reliable method to check the main activated sludge properties: condition of microbial population and flock formation. It also gives information about sludge age.

Technical equipment for paper industry microscopy bases on ordinary light microscopy, but some prerequisites are needed when microbes are the subject of study:

• illumination technique for "wet preparates" = Phase Contrast illumination.
• higher numerical aperture than for other applications to reach distiction of small objects (an example: N.A. > 1.0 for 40x Phase Contrast objective which means the need of oil immersion - type objectives).
• Epifluorescence (UV) illumination (for trouble shooting and test coupon analyses).
• high-sensitive digital camera (to detect objects in Epifluorescence microscopy).

Laboratory technicians, operators and researchers of paper industry are very interested to apply microscopy into their analytical procedure. These methods, however, need time and patience when learning to explain the views on the preparates. Training is first needed to diagnose all the raw materials of the processes, typical paper industry microbes etc. before a microscopist is ready to solve real trouble shooting samples. The knowledge of different type bacteria, protozoa and higher organisms of activated sludge systems is also needed.

There are two ways to collect experience for the evaluation of microscopical preparates: either training alone with different well-known preparates (tip: slides with bacteria can be bought from certain companies) or join courses where paper industry microscopy will be teach (such kind of courses will be held annually at least in Finland).