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Monday, September 28, 2015

Why the Cobb test provides insufficient data

The Cobb size test measures the amount of water a specified area of paper will absorb in a given length of time.

Why does the COBB test (ISO 535 & TAPPI T 441) often provide insufficient or even incorrect information for predicting the behavior of paper/board in the converting process? The below schematic examples show the reason: 

1. Sizing distribution in z-direction: sample 1 and sample 2











high – surface sizing – low
low – internal sizing – high
high – surface sizing – low

2. Water absorption speed into the two different samples (penetration depth over time)
 









3. Cobb test (water penetration depth = volume over time) 










Cobb 1 ≈ Cobb 2
= wrong!

Why can't the Cobb test give this kind of information? The Cobb test gives an average indication about the surface sizing plus internal sizing. No information about surface pore structure or/and surface sizing is possible.

How is this important information about surface and internal properties attained? The Emtec PDA is capable of gathering this information.  In a test cell, the PDA contacts a paper sample with liquid. From the moment of contact, low-energy high-frequency ultrasound is transmitted through the sample in the z-direction.  While the paper absorbs the liquid, the attenuation of the ultrasound undergoes characteristic changes.  The ultrasonic signals are received by a high-sensitivity sensor for processing in the PDA.C 02 from where they are transmitted to a personal computer and displaced as an intensity vs. time diagram.

Example: testing results (time point MAX represents the surface hydrophobic/surface sizing)










MAX (1) >> MAX (2)
= right!

From the shape of the curve the following conclusions may be derived:
  • All quality parameters of paper and especially those surface properties which influence the wetting and absorption of an appropriate test liquid.
  • Quality parameters of liquids that may be characterized by means of a test paper.
  • Converting behavior of industrial paper / paperboard grades and process fluids.



Thursday, September 24, 2015

Budgeting for 2016? Some reminders...

Many are budgeting for 2016. Here at Technidyne we want to be your partner in this respect. We can be involved in understanding:

  1. Instrument needs
  2. Replacement instruments
  3. Service needs
  4. Calibration standards
  5. Testing services
Instrument Needs
Many companies have mandates as they move toward new product offerings, operating cost reductions and data requirements. Technidyne can help evaluate where you are today and what may be the most cost effective way to move forward.

Replacement Instruments
Technidyne instruments are robust and many instruments in the field are well over 20 years old. However, with the Color Touch™ XTEST/Plus™, and PROFILE/Plus™, Technidyne offers many opportunities to update your instrumentation at a reasonable cost while enhancing your capabilities.



Service Needs
Reductions in man power over the years has left many of our customers short handed. They do not have the people to keep up with maintenance and calibration. Technidyne's team of regional service personnel offers greater opportunities to assist on an annual, semi-annual, quarterly or even monthly basis. Service personnel are always close by, but scheduled service saves you money and time.

TEST/Plus Gloss
Calibration Standards
Technidyne is known for its calibration standards offerings. Now with CalStandards.com, anyone can shop, purchase and receive standards on their time frame. New items are being added regularly to meet your calibration and routine service needs.

As requirements and competition changes, the need for additional or new data arises. Technidyne's laboratory offers testing services of many kinds. From round robin testing to receiving data from new tests, there is a breadth of knowledge and data that can help one best decide how to tackle your daily challenges.

Monday, September 21, 2015

Are brightness and tristimulus Z the same?

Both brightness and tristimulus Z are optical measurement results from the blue part of the spectrum.

Brightness
According to TAPPI T 452, the brightness function is defined with the effective wavelength - 457.0 +/- 0.5 nm obtained by the combination of illuminant, glass optics, filters and photodetector as seen in the graph below.  It was defined in the 1930's to assist in measuring the bleaching process. The wavelength and function were built around a copper-sulfate filter which was used in the original GE Brightness instrument.

Tristimulus Z
According to CIE 15-2004, this comes from the 1931 standard observer experiment (2° cone angle) of the CIE which defines how the average person sees color. The Z value specifically relates to how the average person sees blue. It is centered around 445 nm.
Relative comparison of brightness and z-function
People over the years have used the tristimulus Z to estimate brightness. However, they are different functions and will result in different values.  The Z value was used in the newsprint industry for some time and was later replaced with brightness measurement in the 1980's.  Also, since measurements on the Zeiss Elrepho were complicated, many people used the Z value instead of brightness simply to save time. If the spectral curve of a sample is flat in the blue region the values of the two different measurements will be similar if not the same. However, if the sample has a lot of character (up slope or down slope) in the blue region, the brightness and tristimulus Z values can be very different.

Monday, September 14, 2015

Solutions to Common Parker Print Surf Problems

Since Dr. John Parker introduced the Parker Print-Surf (PPS) instrument in the early 1970's, strategies have developed to improve the repeatability (measurement to measurement agreement) and reproducibility (instrument to instrument agreement). Even though there have been many iterations and generations of the original PPS instrument, Technidyne developed a brand new instrument in 2001 that resolved many, if not all of these issues.

Below you can see the list of issues with traditional PPS instruments and the Technidyne solution/approach:

Potential Causes for Error in                          Technidyne's Solution with
PPS Testing                                                        PROFILE/Plus PPS

Air flow measuring device
   - devices are non-linear                                   =>    Multi-point restrictor calibration & paper
   - dummy heads are used to calibrate this               verification

Sealing the measuring head
   - petroleum jelly typically used
       * too little = leaks & high readings           =>    Rubber o-rings
       * too much = clogs & low readings

Flatness of the head                                           =>     Manual lapping

Protective collar
   - burrs on collar may not allow proper seal  =>    No collar
   - collar can pull & cause small creases

Concentricity of guar land                                =>     Each head is mechanically fitted by hand

Instrument air
   - blows on paper, usually mill air                   =>     Dedicated, filtered air source
      that is not clean

Backing material
   - highly variable
   - wears out i.e. becomes heavily                   =>      IRHD hardness is measured on every
      embossed                                                                 backing

Clamping pressure
   - not easy to check                                         =>      External load cell
   - pressure too high = low readings

Thursday, September 10, 2015

TEST/Plus Gloss Available NOW

Technidyne has already shipped the first few TEST/Plus Gloss units to the market. The new gloss instrument is available in 75° and 20° versions. The TEST/Plus Gloss is one of a new generation of laboratory test equipment from Technidyne which 
provides features such as:



  • Fast measurement
  • Meets TAPPI and ISO Standards
  • Adaptive interface
  • Averaging and statistics
  • Data trending
  • Multiple sample evaluation
  • Printer
  • Bluetooth administrative interface
  • Touch-screen user interface
  • Compact design
All TEST/Plus devices have basic measurement capabilities for a budget-friendly price. Additional features can be added by purchasing applications for your particular needs. The Technidyne T480A Glossmeter has been available since the late 1980's. Step into something modern, something inexpensive, something easy to use and something new. Look at the TEST/Plus Gloss.

Thursday, September 3, 2015

Need Calibration Standards: Use CalStandards.com

 
Technidyne has partnered with CalStandards.com to offer calibration standards and recertifications on-line.  Technidyne customers will be able to order their one-time standards, subscriptions and recertifications via CalStandards.com . Once a customer logs on, they will be able to compare prices and frequency of standards deliveries.  Orders can be placed and paid for with a credit card. It's that simple.



Eventually, additional parts and instruments will be available for order directly from the web. Let us know what other items you would like to order via CalStandards by emailing us HERE.




The site will be live September 8 - shop at CalStandards.com .