(ELIMIATE THE VARIABLES)
ACCEPTS THE ALKALINITY CHALLENGE
Roughly ten years ago, (20 in Europe), the US was forced to change from acid based papers to alkaline based papers. Since the offset printing industry was based on a totally acid system, (acid paper, acid fountain solutions, inks & cleaning materials that were formulated for acid papers), the change to alkaline papers has created havoc with our ability to maintain ink and water balance and get inks to dry.
ADVANTAGES OF ALKALINE PAPERS V/S ACID BASED PAPERS.
Environmental! Chlorine and other components used in processing acid based paper created severe problems with regard to polluting rivers, streams and even ground water.
Archival quality! Acid based paper naturally turned yellow or brown with age and eventually deteriorated. Alkaline papers use calcium carbonate for fillers. It is white as snow and does not yellow or degrade with time. Alkaline papers are commonly referred to as acid free papers.
The bottom line! Once the cost of all the R&D is paid off, the cost of manufacturing alkaline papers should be lower than that of acid based papers. One of the reasons for this is that calcium carbonate is basically ground limestone, perhaps the most or at least one of the most prolific minerals on earth. Will we as the consumer ever see the reduction in cost? Probably not!
DISADVANTAGES OF ALKALINE PAPERS V/S ACID BASED PAPERS.
Cross Contamination! The calcium carbonate or precipitated calcium carbonate used in the new papers is for all intense purposes rock! Rock is not soluble in most of the cleaning products we currently use or had been using to clean our press rollers and blankets, (i.e. petroleum distillate washes and solvent based deglazing solvents). As we run paper through the press, the fountain solution and ink moisten the plate which in turn moistens the blanket which in turn moistens the paper. The calcium carbonate, (used as filler), is held in the paper by a starch system. To a certain degree, all moisture will break down this starch system and release the filler which transfers to the blanket, then to the plate and then to the rollers, (both ink and water). In the case of the acid based papers this filler was roughly the same pH as that of the fountain solution and therefore created little or no problem other than dust. In the case of Alkaline papers however, the pH of the calcium carbonate filler is 14. When you consider that alkaline products neutralize acids and now we are introducing a 14 pH product into a 4.0-5.0 pH fountain solution the Alkaline product will raise the pH of the acid fountain solution to the point were it is impossible to maintain ink/water balance. Further more to ad insult to injury the calcium carbonate gets into the pores of the blankets and rollers creating a glaze that is not soluble in standard solvent based washes and if you find a deglazing solvent that will dissolve calcium carbonate, you should not use it without a Tyvek suite, solvent gloves and a fully self contained breathing apparatus! We have seen situations were form rollers become so cross contaminated that they will actually abrade the image on metal plates.
SO WHAT DO WE DO!
1. Run chemicals and inks that are compatible not only with the new alkaline papers but with themselves! Most chemical manufacturers have lowered the pH of their fountain solutions from an accepted range of 4.0-5.0 to a range of 3.5-4.0 and included a chemical buffer which prevents the pH from rising in the presence of alkalinity. Our fountain solutions range from 3.8 &endash; 6.8 depending on your particular application, (type of plate & substrate being printed). Ironically Chemical manufacturers don't make ink and ink manufacturers don't make chemicals so compatibility between ink, fountain solution and cleaning chemicals is hap-hazard at best! We do formulate our own ink, fountain solution and cleaning chemicals and our claim to fame, is that all of the products in our line are designed and formulated for compatibility within thesystem. This is a tremendous advantage when we are trouble shooting print problems, especially over long distance. We know all the formulas and don't have to guess at what some other manufacturer was thinking when he designed his product. Best of all we control change! No more surprises from a manufacturer for whom we are a dealer. Changes to our product do not occur without complete field-testing for compatibility with the entire system.
2. Use cleaning chemicals that are designed to lubricate, lift and rinse calcium carbonate, gum glaze, dried ink, oil and paper dust. We suggest the following procedure be followed to insure optimum print performance.
A. Decontamination of ink rollers and blankets using a roller cleaning paste that penetrates deep below the surface of the rollers and lubricates rather than trying to dissolve foreign material imbedded in roller pores. Doing this procedure with the press running at a medium speed will insure that the centrifugal force will move the contaminates to the surface of the rollers. PROSOL D/C PASTE is just what the doctor ordered.
B. Rinse the paste off the blankets & rollers with a good water miscible or non-petroleum based roller wash. BWRW-4 Water Miscible or Prosol I.E., (ink eradicator), environmentally responsible wash.
C. Finally, to insure that there is no high pH calcium carbonate left on the rollers, we recommend the use of CRRP calcium rinse and roller prep. This product contains three types of acid and is dripped on the rollers with the press running. You do not rinse the rollers just moisten them. The acids are not harmful or offensive but the combination will bring a 14pH particle down to a neutral 7pH and it simply becomes filler for your ink.
3. Decontaminate your recirculating system. The recirculating system unfortunately becomes a catch-all for everything that is used in the printing process. We recommend the use of a systems cleaner such as PROSOL PRCSC. The use of this type of cleaner is time consuming and the end product should be treated as hazardous because of everything it contains when you flush it. Here is were the use of compatible chemistry comes into play. When ink, fountain solution and cleaning chemistry are compatible, you will undoubtedly use less ink and water. This means that the starch system in the paper does not break down as rapidly resulting in less pigment floating in the fountain solution and less cross contamination, which means the recirculating tanks stay much cleaner. In addition to our recirculating system cleaner, we strongly recommend the use of our filter bags in the recirculating tank. These bags filter the water on its return from the pans catching ink, paper dust and about 60% of the calcium carbonate released from the starch system of the paper, before it reaches the holding tanks. This drastically extends the period between required use of the systems cleaner.
4. There is still one more area that requires attention to insure optimum performance from your equipment, the continuous dampener. As we talk about rollers, keep in mind that rollers that are to carry ink need to be sensitized, (they must attract ink), this is accomplished by blanket and roller washes acidic rinses etc. On the other hand, rollers that are to carry water must be desensitized, (they must repel ink and allow very smooth films of water to be transferred to the plate). Knowing that the blanket and roller wash will sensitize all rollers it comes in contact with, why would one wash a water unit with blanket or roller wash. We recommend a product called Blue Star dampening system cleaner and desensitizer. It is applied to the dampening unit with the press running and the pans drained. You allow it to run in for about one minute during witch time, it will dissolve dried ink and gum glaze on the water unit. You then carefully run a damp sponge across the top water roller wiping off the excess Blue Star. You have just cleaned, desensitized and gummed your entire water system in one step and are ready to resume printing.
P.O. Box 519, Goldenrod, Fl., 32733-0519 U.S.A.