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Ink Management and Stencil Processing

(November 2001) posted on Mon Nov 05, 2001

Problems and solutions

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By Carol Swift, Peter Kiddell

The amount of ink that many printers waste because of bad organization must bring joy to ink suppliers and sadness to the printers' accountants. Poor ink management and the problems it creates often aren't recognized until a company experiences a change in management or the inkroom staff.

We saw an example of poor ink management in a company where we recently consulted. This company was annually discarding approximately $100,000 in ink. Disposing of this amount of ink as waste represented a severe financial blow to the company.

The problem developed over years for a variety of reasons. Inadequate stock rotation was one cause, while the inability to estimate ink needs properly (mixing 10 gallons when only 5 were needed) was another. Additionally, labels covered in ink made it difficult to find existing batches of mixed colors, and frequent mismatches led to more unusable ink piling up in storage.

The company used both solvent-based and UV inks. Solvent inks with lids tightly closed can have a shelf life of several years if they do not contain a catalyst. UV-curable inks, however, are nowhere near as stable. They must be stored between 50-77°F (10-25°C) and have a shelf life of around 12 months. Storing them at temperatures above 77°C shortens their shelf life. Dropping them below 10°C and approaching freezing can also damage the ink.

Once these problems were discovered, the company began rectifying the situation by checking its store of UV inks. Those that were undated or more than 12 months old were scheduled for disposal. The remaining inks were set aside to be cataloged.

Solvent-based inks were treated in a similar manner; but in their case, mixing dates and storage age were not as important as the condition of the ink. If the lid was not firmly secured, the inks were marked for disposal. There is no point trying to revive ink that has completely lost its solvent balance and formed a thick crust of dried material on the surface.


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