Remember that the degree of leveling controlled by rate of adsorption of the dyes is a function of the % of adsorbed dye per contact. Consequently, in order to use the same dyeing cycle on the different machines is absolutely necessary that the estimation of contacts has to be equivalent.

Additional goals of the design of dyeing processes using contacts as duration pattern consist in the possibility of minimize the pollution of the effluents, managing the levelness by physical means instead of chemical means. By the way, that is also a very important precondition to improve the Color reproducibility from lab to lab, from lab to plant and from lot to lot in the plant.

A very important additional aspect consists in the adaptation of the mechanical and hydraulically performances of the machine to the physical properties of the dyeing goods. Too often happens that the most used way in order to ensure a tolerated levelness consists in the increment of speeds (pump and/or goods). That is the FIRST WRONG INTERPRETATION of our CONTACTS CONCEPT. I allow me to repeat a sentence in one of my lectures: "if the textile fibers could cry, we will never be able to entry in a dye house".

Since the first publications have mentioned this new approach and commented the achieved performances, a lot of interesting reactions have tried to make interpretations and to extrapolate in any direction this concept.

Three main groups have to be mentioned this respect:

1. Machine makers
2. Dyestuff producers
3. Technical schools

Some (interesting ?) aspects to each reaction:

To 1.-

• Force to keep the Contacts duration constant during the whole dyeing process. In the best case: limit either the difference of pressure (packages and beam dyeing) or the speed of the goods (piece dyeing in rope form)
• Increase the interaction bath/goods in order to be able to use the existing (generic) dyeing cycles.
• In piece dyeing machines (working in rope form), exist a confusion between rope speed and contacts. Some machine makers (as example: MCS, Sklavos, Gaston County, ATYC, etc.) as well as companies involved in dyeing programmer building (Termoelectronica, Barco, Schermuly, etc.) are claiming their machine works "with contacts". The reality shows: a) IT IS IMPOSIBLE to apply on each machine the SAME dyeing cycle, b) The dyeing cycle has to be corrected if the load of the machine has changed, 3) Changing the speed of the rope, the cycle will change proportionally producing problems, specially by acceleration of the rope speed. Each machine and each load needs special cycles, absolutely contrary to the meaning and sprit of CONTACS, 4) The basic criteria for designing correct dyeing cycles called "% exhaustion per CONTACT" has no more a general validity, because the used processes are only based on empirical knowledge.
• They have the merit, that at least, ONE variable of the system can be controlled in order to avoid variations in the machine/goods interaction. But that is not enough in order to design optimized dyeing cycles. It counteract only some NON-CONSTANCIES in the dyeing machines. No way to forecast which process has to be used for new loads, new recipes, new articles, etc.

The presumption or prediction of the best pump or rope speed can only be done in a general way, but it can not be evaluated on-line according to the kind of goods, the limits supported by the textile material, the data of each current lot on a different machine.

In any case, the respect of the quality of the goods is missed. And if limits are established: if the limit will be overdone: which kind of correction will enter in action? How the % adsorption per contact will be compensated?

To 2.-

• The relationship between activation of the dye adsorption and the use of other activation energies as the temperature will never be taken in consideration.
• The only metering or dosing recommendations are always related with the addition of alkali in the dyeing with reactive dyes. In very few cases, some mention will be made on the "convenience of addition in portions", without further details.
• The complete "control of levelness" will be ensured through temperature profiles. Some "minimal performance of the dyeing machine" will be mentioned in some cases. An example of assumption: "For a level dyeing, the dyeing machine has to achieve 2 contacts/minute", what is completely wrong.
• The concept "tolerated % exhaustion / CONTACT" will be never used, because it will allow to change easily products and dyes. The customers are treated like as in the time of "specialties" as long as possible. It is clear that the strategy "support the customer dependency" remains commercially valid.

In any case, the respect of the quality of the goods is also missed. That according to the system fiber/dye used a given temperature profile and specially end temperature has to be used in order to ensure the minimal rate of diffusion, as basis for duration for good reproducibility and good fastnesses, is not enough for keeping the rate of adsorption from the beginning just so close as possible to the tolerated limit for ensuring a tolerated levelness.

One of the most classical consequences: by sampling it is not always sure, that the sample used for Color control represents the whole lot, because the levelness is not ensured. Result: wrong adds, additional costs, no improvement of the production quality.

The use of dyeing auxiliaries increasing the migration properties of the system can compensate the control of "% exhaustion per contact", but leads always to poor Color reproducibility, especially changing the liquor ratio (partial loading of the dyeing machines).

To 3.-

• The complexity of designing of dyeing cycles, to use of such dyeing cycles on each dyeing machine, the automation of creation of dyeing cycles for increasing demand on new Colors to be delivered in the shortest time (market requirements increase this respect, see "Just in time", "Right First Time" and other key parameters more and more used in industrial terms) is not recognized, putting special emphasis in "ways to get exhaustion curves which helps (?) to design dyeing processes" (but can not be used on line in a current production).

To all.-

• Textile industry is demanding more and more diversification, only in few sectors can "standard production" be achieved. In an European and American (in near future also Asiatic) textile dye house it has to be prepared to face the production of 2 new recipes (new Colors on existing substrates or existing Colors on new substrates) a week for installed dyeing machine. This figure comes out of the precondition assuring a full occupation of the installed dyeing machines. That means, not only recipes have to be developed, but processes ensuring the RFT or at least RST (Right Second Time). The delivery time (Just in Time) can no more depend of the corrections a new Color needs in the production…
• Only with very complicated management tools for the on line disposition of lots (recipes and dyeing cycles) can allow to be near to an optimized dye house production. But it is obvious that such system has to cover a lot of so called "exceptions" and "specific cases", making very difficult to maintain a good transparency of the designed system.
• Only accepting the common valid unit of CONTACTS can be achieved a rapid and sure evaluation of the kinetical behavior of dyeing recipes. It presumes well defined data bases related to dyeing machines, classes of substrates, interactions style/machine or material/machine allowing to shorten the disposition time, to call all relevant date for each single lot and to manage on-line all the data without manual intervention. Additionally, takes care of the dye goods, allows changes in the mechanical and hydraulically values without changing dyeing cycles and last but not least, decreases the economical and ecological impact of corrections.
• Using an inappropriate value of the UNIT CONTACT, means that it is no way to compare the limits of good levelness (or acceptable levelness) in terms of "% exhaustion / CONTACT". In this case the extrapolation of processes from a machine to another, from a plant to other plant is no more possible. The so called "Process by Contacts" is again based on empirical values no allowing to predict dyeing processes and only valid for specific dyeing units. That is the case of devices build by companies without our assistance and control.
• The support my people and I are given to the licensed companies ensures any update of the original algorithms, based mainly on the practical experience of our consulting activities. The algorithms defining the relationships necessary to coordinate in order to achieve to the CONTACTS definitions, are exclusively accessible to our licensees. They have never been published and are not of public knowledge.

We have ensured the support tom following companies in order to make possible that dyeing cycles can be used on ALL the machines using autoregulated devices according to our requirements, respecting the quality of the dye goods to be dyed and taking in account the future requirements concerning effluents and respect of the environment: