Some of the findings on newer low VOC washes and how this greener, more sustainable chemistry may affect your pressroom:
“Printers using Low VOC vegetable oil based washes should be advised that these washes can/have cause the following problems when not properly cleaned out of the system.
1. Plate sensitivity… 2. Ink density fluctuations…”
ECO-range BLANKET & ROLLER WASH. Hollywood, FL: Allied Pressroom Products, 2007
“Some newer blanket washes have very low VOC contents and these solvents provide another alternative to conventional high VOC containing blanket washes. These new washes are made from vegetable-oil-derived materials but require changes in how the operators clean the presses. The washes leave a residue that requires further cleaning or there will be unacceptable swelling of blankets and rollers.”
Jones, Gary. "Becoming a Sustainable Green Printer." Printing Industries of America: The Magazine May 2009: 35.
“(Ester/vegetable based wash) was the easiest product to apply as it has a very oily viscous nature and does not drip easily. It cleaned fairly well in terms of ink removal especially when used as a manual cleaning wash, but the product had a tendency to leave a greasy residue on the blanket and rollers. Removing the solvent itself became a major, and frustrating process.
When the product was finally removed from the rollers, and after a prolonged drying time, it was felt that it left the rollers greasy….
When used in the automatic wash system (it) caused significant problems. Viscosity was an important shortcoming of this wash as it clogged parts of the automatic wash system.
The wash solvent is transferred to the blankets via a wick felt contained within a holding tray; this became blocked with oil and began to deteriorate. The felt wicks had to be removed and replaced and the machine stopped for a day. Cost of damage to such systems can be significant…”
Evaluation of vegetable-based biosolvents for use as cleaning agents in the printing industry, Copeland , Turley, Palmer, Kingman, Elskildsen & Bresolin (2005).
Low VOC washes and your pressroom’s performance:
New low VOC regulations have limited the number of compounds and solvents that formulators can use to develop low VOC and VOC compliant pressroom products. Among these chemicals, one type that is most frequently used is Esters (fatty acid oils or vegetable oils). Although Esters are a good cleaner that can effectively break down printing inks, they tend to leave behind oil residuals that unnoticeably penetrate the composition of blankets and rollers and negatively impact your printing.
The initial application of an Ester based wash may clean successfully and show little or no effect on your ink, blankets, rollers or print job when rinsed properly. However, frequent use of these types of cleaning solutions subjects your blankets and rollers to oil penetration; a process in which the Esters leach, or seep, beyond the surface of your blanket or roller, and into its composition. Once the Esters get into the composition, especially that of your rollers, it is very difficult to extract them.
Rinse Aids and Step 2 washes are recommended (in many cases required) as a follow-up when cleaning with Ester washes, however most of the time they only work on removing oil residue from the surface of the rollers. Neither Rinse Aids nor Step 2 washes are effective in removing oils that have already migrated below the surface of the roller and incorporated into the roller’s composition.
Once the oil has seeped into the composition, oil retention has begun. This is referred to as roller oil retention, whereby the rollers retain the oil from the Ester wash (or blanket oil retention when pertaining to blankets). In many cases, the level of retained oil continues to increase with each application of the Ester-type wash until the roller or blanket can no longer absorb and/or retain oil.
The early signs of oil retention are fluctuation in ink density and difficulty maintaining ink and water balance. As ink is applied to rollers that have retained oil, the ink’s standard “tack” begins pulling retained oil from the composition of the roller to the roller’s surface. This oil mixes with the ink causing ink contamination. Once the ink has been contaminated, its standard properties, as designed by the ink manufacturer, have been altered. The ink’s density is no longer the same and maintaining ink and water balance becomes very difficult, even with constant monitoring.
The secondary sign of oil retention is blanket and roller swelling. This commonly occurs after continued use of Ester-type washes, often with uneven and bubbled swelling, but sometimes with swelling of the entire surface. Either way, print quality drastically decreases to the point that it is unacceptable. In most cases, once swelling occurs a pressman’s only options are to use a high VOC cleaner and multiple wash-ups to try and remove the retained contaminants, or replace the affected blankets and rollers entirely.
Is there another alternative?
Explorer Pressroom Solutions believes that there is.
When we began developing our Sustainable Series line of products at the beginning of 2007, we set out to create ultra-low VOC products knowing that they had to be different than products that would eventually be offered in the industry. Familiar with Ester type washes and their limitations, we knew it was vital to create products that would not only be effective cleaners, but products that would help our customers over the long run; products that would clean well without negatively impacting the mechanics of their press or compromising the efficiency of their pressroom or quality of their work.
The result was the formulation of our ALPHA™ press washes, an entirely new type of Patent Pending pressroom chemistry designed, and independently tested, to provide excellent performance without leading to blanket and roller oil retention or the complications that result from it.
Our ALPHA™ washes are revolutionizing the way pressrooms deal with low and ultra-low VOC cleaners. No desensitizing, no ink issues, no swelling, no changes to the mechanics of your pressroom, no strenuous or labor intensive wash-ups… just effective, easy to use pressroom chemistry.