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May 1, 2011 12:00 AM
When it comes to removing hickeys caused by substrate or press conditions, the arguments rage as to what works. In my experience, for most items to work, it is a matter of extent and implementation. Consider the pros and cons of these cleaning methods.
These units turn the load, jog, aerate and position the substrate on the skid. Aerate is the key word. Blowing out all loose coating and debris is valuable and is a good first step in substrate cleaning. This works for plastic and sheeted paper. A side benefit to jogging and aerating the load before printing is far fewer tipoffs in the feeder.
If you are printing on clear plastic, a non-contact sheet or web cleaner usually is used to prevent scratches. A roller of tacky material that rides against the web and collects material can be used when printing on paper. These are very effective and offered in a wide range of prices.
For sheetfed presses, there are contact and non-contact types. For cleaning paper, I prefer the contact type — either a stationary brush or a rotating brush.
Years ago, a sheetfed printer argued against a sheet cleaner because he felt clean paper was the responsibility of the paper company. I asked him if he conveyed this thinking to the paper companies, and he stated that he had done so for the past 20 years. Then I asked him, “And how successful do you feel you have been?” That ended the discussion. Sheet cleaners are a wise investment.
There are several on the market, and they do perform well for both sheetfed and web presses. Use a jogger/aerator, sheet cleaner and then the dampening system modification.
Do they work? Yes, but there is a price to pay. They collect material from the press and generally hold it until you clean the roller. If the roller is in the No. 1 position nearest the dampening form, then it is difficult to access and clean. It is easy to clean in the last position, but because it is the last roller over the plate, it can leave a pattern in dots that you might not like when printing on coated paper.
There is some food for thought on how you are going to address the issue. Remember that nowadays, the number of hickeys allowed in a job is ZERO.
Before you start doing anything: Clean up your press and pressroom. I have never seen good work printed on a filthy press, nor have I seen productivity on a dirty press with broken parts.
Raymond J. Prince, vice president, Technical Consulting Group, NAPL, is a leading expert in pressroom technical and operational issues. Contact him at (605) 941-1492 or firstname.lastname@example.org.