Technidyne Header Image

Monday, December 23, 2013

What's a reasonable color tolerance?

A customer recently asked, "What are visually perceptible color differences in L* a* b* coordinates?" The answer is not so easy.

Generally speaking in the Paper Industry we are normally dealing with near-white colors. In that case, we often use the rule of thumb that +/- 0.3 in L*, a* or b* is visually perceptible. However, when we start to look at more saturated colors the question becomes much more difficult.

L*a*b* color tolerance
Color tolerance vs. Visual acceptability
If we set a tolerance based on L* a* b*, the color space we are looking at is cubical. However, when we plot actual visual acceptability it is more ellipsoidal-shaped.  See at the right, the black shading represents numerical acceptance, but visually unacceptability.

Obviously, there is a difference here. If we look at the ΔEcmc tolerancing which is based on ellipsoidal tolerances, this does a much better job of matching visual and numerical acceptability.  Looking at a particular cross-section of the a* b* space (below), we can see that the visually acceptable ellipses vary in size depending on the position in color space. The ellipses in the orange area of color space are longer and narrower than the broad and rounder in the green area. The shape of the ellipses are larger as the color increases in chroma (away from a*=0, b*=0).
This means that visually acceptable differences in L*, a* and b* differ depending where we are in color space.  A Δa*=0.5 would be noticeable on a near-white, but Δa*=5.0 on a red may not be noticeable.

If you have more questions about this topic, contact me at toddp@technidyne.com.



Monday, December 16, 2013

Thursday, December 12, 2013

Technidyne Christmas Lunch 2013

December 11, 2013, Technidyne had its annual Christmas lunch.  All employees were treated to a buffet lunch.  After lunch the appropriate department manager recognized employees celebrating significant anniversaries as employees at Technidyne.
There were four employees recognized:
  • 15 years -Micky
  • 15 years - Robin
  • 20 years -Rocky
  • 30 years - Gary
We are very proud of the fact that our average tenure is 17 years for all employees.  Several employees who at one time or another left for various reasons have returned to a great US-based, family owned company.

It takes time and effort to find the right people, but when we do they stay for a long time and contribute to our DNA: Technidyne's passion for customer satisfaction drives us to be the best in the world at developing economical and creative solutions.

Sunday, December 8, 2013

Paper Roughness (Smoothness): Part 7 - Applications

Some of the other reasons for testing roughness are related to converting processes. The die-cut sheet feed in an envelope machine requires only one sheet at a time to be picked up and transferred, whereas multiple sheets will cause paper jams. The coefficient of friction between plies has a high correlation to Sheffield measurements.

There are some applications where metalized films are applied to the surface of paper. The reflectance properties of the film can expose wire marks on the base sheet. This is another example where the gentle loading force of Sheffield test better replicates end use properties of the paper, as compared to the PPS test.

Many plastic films are packaged in reams, like paper, for use in a photocopier to produce overhead projector transparencies. When the surfaces of the films are extremely smooth, there are static forces and cohesive forces that interfere with single sheet feeding. The manufacturers of such films generally create rough surfaces that enable an air film to exist between sheets. It is common to use Sheffield test results to control the process that generates the rough surface. Again, the PPS test would have measuring head loading that is excessive for this test.

When selecting a test instrument for paper, it is important to understand the relationship between the end-use of the product and the physical test parameters of the instrument. A further requirement is to use a test where process control settings on a paper machine (or plastic web processing equipment) can be modified to optimize the final product for its intended end use. The old adage was “If you can’t control it, why measure it?” In today’s marketplace, the customer will be able to find a supplier who makes the product he wants.

Related posts include information on the relationship between paper roughness (smoothness) and the following items:
  • Papermaking Process
  • Printing processes
  • Formation
  • Parker Print Surf Test
  • Sheffield Test
  • Applications

Wednesday, December 4, 2013

Video: Calibrating Your Technibrite Micro TB-1C

We have been working on some new videos to add to our Technidyne YouTube Channel.  One of the latest videos is the calibration of the Technibrite Micro TB-1C which can be seen HERE.

 

We are posting product videos, calibration videos and maintenance videos. 

If you have ideas of other videos that would be helpful to you, please let me know by sending me an email at toddp@technidyne.com.

Sunday, December 1, 2013

Paper Roughness (Smoothness): Part 6 - Sheffield Test

The Sheffield test:
The xerography and inkjet processes are common examples of processes where the PPS tester does not replicate the loading factors. The Sheffield test subjects the paper to loading pressures of 0.09 mPa at zero Sheffield units, and 0.154 mPa at 400 Sheffield units. The reason for the non-constant loading is related to the design of the air system, and the “hovercraft effect” of the variable pressure between the measurement lands. When the PPS instrument is set to measure at the lowest loading pressure, it is still about 4 to 5 times higher than the Sheffield loading.

With the introduction of digital Sheffield testers in the late 1980’s, the Sheffield method maintained its prominence for these grades, at least in the USA. There are many regions of the world where the Bendtsen test is used; however, the correlation between Bendtsen and Sheffield for these grades is excellent. There are many grades where the Sheffield method gives more uniform results than Bendtsen; those grades being the higher basis weight and stiffer grades, where the Bendtsen deadweight is not heavy enough to fully flatten the sheet under test.

Related posts include information on the relationship between paper roughness (smoothness) and the following items:
  • Papermaking Process
  • Printing processes
  • Formation
  • Parker Print Surf Test
  • Sheffield Test
  • Applications

Wednesday, November 27, 2013

THANKS!

Thanksgiving in the US gives us a chance to reflect on all the things we are thankful for in our lives.  We can reflect on the history of the country and be thankful for the sacrifices and ingenuity of those that came before us. We can reflect on our jobs and the great people we interface with: coworkers, customers, vendors, and agents. We can reflect on our family, friends, faith and blessings all around us.  We all have a lot to be thankful for. The hard thing is to take time to think about it and then to actually say, "thank you", out loud to those that have helped us achieve out position in life: spouse, parents, friends, kids and God.

Sunday, November 24, 2013

Paper Roughness (Smoothness): Part 5 - Parker Print Surf Test

The Parker Print Surf test:
The Parker Print Surf tester was one of the first roughness testers that featured both quick test results and a digital display. Since it had those desired features, it showed up in applications where test conditions had no relevance to the nip loading for which the PPS was designed. The PPS loading was designed to replicate the conditions of offset, gravure, and letterpress printing processes; where the operator could select 0.5 mPa, 1.0 mPa or 2.0 mPa loading. The theory was that paper under test should be subjected to the same compression loads found in a printing process.


Related posts include information on the relationship between paper roughness (smoothness) and the following items:
  • Papermaking Process
  • Printing processes
  • Formation
  • Parker Print Surf Test
  • Sheffield Test
  • Applications

Wednesday, November 20, 2013

Thanksgiving Lunch

We just celebrated our annual Thanksgiving Lunch at Technidyne. We were missing a few employees that were traveling and ill, but we had a great pitch-in meal.  Ham, side dishes and dessert were all delicious (as usual).  We played BINGO after lunch. Our 5 winners each selected a prize (below).

 









We have a lot to be thankful for here at Technidyne:


FAMILY    FAITH     FRIENDS

   HEALTH       AGENTS

CUSTOMERS

Tuesday, November 19, 2013

Visiting Argentina

November 15th, I spent time with Mr. Sebastian Caputo, Owner, of RESAICAR our agent in Argentina.  

Technidyne and RESAICAR have worked together in Argentina for over 20 years. We spent time reviewing the economic conditions and market strategies in Argentina and Uruguay.  RESAICAR sells high quality testing equipment from around the world as well as technical support and complete after-sales services to the Pulp, Paper, Printing, Packaging and Forensics Industries.

Sunday, November 17, 2013

Paper Roughness (Smoothness): Part 4 - Formation

Formation:
There is an interrelationship among roughness, porosity, and optical formation measurements. Those regions that are calendered the heaviest will be smoother, denser, and will have lower opacity than the adjacent regions that are calendered lightly. Local variations in opacity will show up as having poor formation on optical formation testers. A rough surface will absorb more ink, and that same rough surface will be more porous, as it received less calendering action. The more porous region will also absorb more ink into its interstices. When printers correlate poor printing with poor formation, perhaps it is the roughness and porosity variations that are the culprits, and the formation tester is one additional piece of test equipment that verifies the root of the problem. These formation problems
occur on a small scale, smaller than what a basis weight process control system will discriminate. Formation problems are perhaps quite detectable by analyzing the standard deviation of porosity and roughness measurements within a small region. The roughness and porosity variations caused by fiber flocs are much smaller than the test area of either the roughness or porosity measuring heads. There can be other reasons for high standard deviations, such as non-uniform sizing, which may also be caused by the localized absorbency properties in the region of fiber flocs.

Related posts include information on the relationship between paper roughness (smoothness) and the following items:
  • Papermaking Process
  • Printing processes
  • Formation
  • Parker Print Surf Test
  • Sheffield Test
  • Applications

Thursday, November 14, 2013

Visiting Chile

(L-R) Arturo Rodriguez, Todd Popson, John Bannister, Daniel Bannister
November 13th, I spent time with Mr. Daniel Bannister, Director, of TIAR Ltda. our agent in Chile and the rest of the management team.  Founders, Arturo Rodriguez and John Bannister, and their sons Arturo Jr. and Daniel spent time reviewing the economic conditions and market strategies in Chile with me.  

Technidyne and TIAR have worked together in Chile for over 20 years.  TIAR sells high quality testing equipment from around the world as well as technical support and complete after-sales services to the Pulp, Paper and Mining Industries. They have people located in the three main regions in Chile.  They have always provided top-notch service and technical support to their customers for years.  It is a pleasure working with professional companies like TIAR that put as much emphasis on service as Technidyne.

Tuesday, November 12, 2013

Visiting Brazil

Poli Instrumentos sales and service team
November 11th, I spent time with Mr. Richard Machoczek, Director, of Poli Instrumentos Ltda. our agent in Brazil.  Technidyne and Poli Instrumentos have worked together in Brazil for over 20 years.  Poli Instrumentos offers high quality testing equipment from around the world as well as technical support and complete after-sales services to the Pulp, Paper, Printing and Packaging Industries.

Within the last year Poli Instrumentos moved into new facilities which gives them greater capability for testing, service and training just outside Sao Paulo.

Sunday, November 10, 2013

Paper Roughness (Smoothness): Part 3 - Printing Processes

The Printing Process:
One of the most important reasons for measuring and controlling surface smoothness is for print quality. For the contacting-type printing processes, the ink film will transfer to a paper surface upon physical contact. When the voids in the paper surface are deep enough prevent such contact, ink will not transfer to the low spots, and non-uniform ink transfer causes poor print quality. When the ink film is adjusted to achieve satisfactory print density on the rough areas of a web, the same ink film may be too heavy to achieve optimum print quality on the smoother portions, perhaps causing mottle and other problems.

Xerography Processes:

There are many reasons why the manufacturers of photocopy machines have target ranges for Sheffield roughness. A xerographic machine needs optimum paper surface properties for reliable sheet feeding, image transfer, and image fix. The fix level decreases as the Sheffield roughness increases, as it affects toner adhesion. Print density loss is observed as roughness increases. There also can be image problems with papers that are too smooth. Toner particles can be flattened and appear as larger dots, thus increasing the perception of the background. Rougher papers produce less background. With regards to paper handling, smoother papers are less stiff for a given basis weight. Smoother papers increase “electrostatic tacking” in the image transfer process. The coefficient of friction decreases with increasing roughness, a factor that is important in sheet transfer operations. The Sheffield roughness properties are carefully specified for the
electrostatic copier printing process.

Inkjet printing:
Similar to the photocopy machines, inkjet printers have paper handling requirements. The method in which a single sheet is transferred from the supply stack generally relies upon the friction differences in paper-to-rubber versus paper-to-paper in a stack. In recent years, there has been development work on optimizing 2-sided surface roughness for ink jet printers. The printing surface was manufactured to be smooth for image quality and the back side was rough in order to facilitate paper feeding and also to avoid excessive contact with a freshly-printed surface as printed sheets are successively stacked in the printer tray.

Related posts include information on the relationship between paper roughness (smoothness) and the following items:
  • Papermaking Process
  • Printing processes
  • Formation
  • Parker Print Surf Test
  • Sheffield Test
  • Applications

Thursday, November 7, 2013

Video: Calibrating your S-4

We have been working on some new videos to add to our Technidyne YouTube Channel.  One of the latest videos is the calibration of the Brightimeter S-4M which can be seen HERE.

We are posting product videos, calibration videos and maintenance videos. 

If you have ideas of other videos that would be helpful to you, please let me know by sending me an email at toddp@technidyne.com.

Wednesday, November 6, 2013

Color Touch Training Session in Asia


Technidyne is currently providing an advanced Color Touch training session to its agents and distributors in Asia.  Three knowledgeable Technidyne staff members are running the training session this week in Bangkok, Thailand.  Technical staff representing China, Indonesia, Malaysia, Taiwan, Thailand, and Vietnam are in attendance.

If you have questions about your local contact, look at our World Directory.

Sunday, November 3, 2013

Paper Roughness (Smoothness): Part 2 - Papermaking Process

The Papermaking Process:
There are several manufacturing processes that shape a continuous web and wind the product on a roll. When metallic materials are plastically deformed through a series of roll nips, the end product is quite uniform, due to the malleable properties of the materials. The modulus of elasticity is quite high for metallic materials, as compared to that of paper. Metallic materials leave a roll nip substantially the same thickness as the roll gap, with a surface finish somewhat equal to the roll finish.


By comparison, paper is extremely compressible. There are numerous voids in paper, including the presence of air within the fibers, which resemble small capillary tubes. In the calendering process, the nips are loaded to a certain nip pressure, “pli”, or pounds per linear inch. The resulting distance between the mating roll surfaces is primarily a function of the nip loading, the compressibility of the paper and the deformation of the roll surfaces. The mechanical action in the nip imparts a smoother surface on the paper, and there is a decrease in the thickness of the web after it is calendered. Further, there is a difference in the stacking height of such calendered papers, due to both the thickness reduction, and the way in which rough surfaces stack together. The properties that affect stacking height are surface roughness, compressibility, and stack
loading.

When building a reel, the highest priority is to wind a uniform roll, as a roll with ridges and valleys will give a perceived value of poor quality, and also there can be runnability issues with such rolls.

The process control systems in use today have a strong history of development around basis weight, moisture, and caliper (thickness) control. Basis weight and thickness variations can cause the calendering action to be different across the web. When a web has reasonably uniform basis weight, but has caliper uniformity problems, a process control system can make very small, but effective adjustments to the calender stack to build a level roll. Such adjustments may affect the smoothness profile, but generally there are no on-line sensors that provide such feedback. When a CD strip from a reel is run through a profiling smoothness tester, there are generally regions of high and low smoothness values that show up at the same places, reel strip after reel strip. When the smoothness values fall within the accepted limits, there is generally no concern in fixing the problem. The astute production manager will observe such trends, and take action before the measurements reach upper or lower control limits.

Related posts include information on the relationship between paper roughness (smoothness) and the following items:
  • Papermaking Process
  • Printing processes
  • Formation
  • Parker Print Surf Test
  • Sheffield Test
  • Applications

Thursday, October 31, 2013

Pulp Inspector Features Color Touch for Pulp Measurement

A Technidyne Color Touch PC has been operating in a new Techpap Pulp Inspector at Fibria Celulose, Aracruz Mill, in Brazil since July 2013.

The Techpap PulpInspector is an automated pulp testing device. It has the capability of:
  • Fiber morphology
  • Canadian Standard Freeness (CSF)
  • Dirt & shives
  • Handsheet making
  • Grammage
  • Brightness
  • Color
  • Whiteness
  • Fluorescence
  • ERIC 950 residual ink
The particular unit in Brazil has the basic handsheet forming and grammage measurement with the addition of the optical properties tests through the use of the Color Touch.

Please contact us if you have questions about the PulpInspector or other Techpap products.

Monday, October 28, 2013

Paper Roughness (Smoothness): Part 1 - Terminology

Terminology:
The terms “smoothness” and “roughness” are generally well understood as far as a dictionary meaning goes; however, the use of the terms in test methods is sometimes confusing. In the title of a test method, the term “smoothness” is used when an increasing number is correlates with a smoother surface measurement. An example of this would be the Bekk method, where a smoother surface requires more time for a given volume of air to leak across the surface. Since the reporting for Bekk smoothness is in units of time (seconds), a surface that measures 500 Bekk seconds is smoother than a surface that measures 200 Bekk seconds. If the Bekk instrument was originally configured to report in Bekk flow, which is the reciprocal of Bekk time, then the test methods would categorize it as a Bekk roughness tester.

The two most common instruments that directly report airflow across the surface are the Sheffield and Bendtsen methods. A rougher surface causes higher airflow; therefore these instruments are designated as roughness testers. The Parker Print Surf method is also a roughness tester; however, the reporting (in microns roughness) is a function of the cube root of the measured air flow. In the last few decades, the zeitgeist has been to accurately name the test methods in accordance with the function and not to continue using the manufacturer’s earlier assigned name, if it was not technically correct.

Roughness Testers: Bendtsen, Parker Print Surf & Sheffield

Smoothness Tester: Bekk


Future posts will include information on the relationship between paper roughness (smoothness) and the following items:
  • Papermaking Process
  • Printing processes
  • Formation
  • Parker Print Surf Test
  • Sheffield Test
  • Applications

Wednesday, October 9, 2013

Video: Calibrating Your Color Touch 2


We have been working on some new videos to add to our Technidyne YouTube Channel.  One of the latest videos is the calibration of the Color Touch 2 which can be seen HERE.

We are posting product videos, calibration videos and maintenance videos. 

If you have ideas of other videos that would be helpful to you, please let me know by sending me an email at toddp@technidyne.com.

Monday, October 7, 2013

Softness Data: What Does it Mean?

The output of the Emtec TSA goes far beyond just giving a single softness number with excellent correlation to hand feel panel tests. It provides all the data needed to explain the softness number so a determination can be made as to why one product is softer than another.  The feeling of softness one gets from a sample is a combination of three main parameters: softness, structure and stiffness.  Here is an explanation of some of the outputs generated by the TSA:

TS7 - Softness Parameter
The TS7 softness peak is the frequency peak that occurs around 6.5 kHz on the noise spectrum graph.  This peak represents the pure softness and is influenced by the fiber furnish, the degree of refining, the chemicals and other factors concerning the real softness of the sample.  Generally, softer samples produce a lower TS7 peak.

TS750 - Structure Parameter
The TS750 structure peak is the peak at a frequency that falls around 200 - 1,000 Hz. However, this frequency is not fixed like the TS7; it can vary in this range.  This peak represents the structure of the sample which includes such things as creping and embossing.  Generally, samples with lower structure strength will produce a lower TS750 peak.  The creping and embossing process is done to realize a specific structure as it relates to hand feel.  Creping and embossing will tend to make this peak higher.

D (mm/N) - Stiffness Parameter
This is the deformation of the sample under a defined load and refers to its stiffness.


HF - Hand Feel
This HF number is the calculated figure which corresponds and correlates with the Hand Panel Test.  The higher this number is the softer the test sample is and the better it is with respect to hand feel.  Hand Feel is when someone touches the sample by hand and ranks it.  This is a combination of the other parameters described above: TS7, TS750 and D.