Although printing blankets may appear similar on the surface, there are a number of factors to consider when selecting the proper blanket for your press and printing application.
Printing blankets have many physical properties that vary depending upon the manufacturer and the blanket style. Characteristics such as:
- print quality
All these properties should be considered when trying to decide on the best blanket to suit your printing needs. The best assurance of choosing a quality blanket is to buy from a reputable manufacturer that can consistently supply you fresh products with uniform quality in every delivery.
Some additional features of a high quality offset printing blanket should include:
- Identification marking—on the fabric side of the blanket, there should be a way to identify the manufacturer and the style of the blanket. The markings should include:
- name of manufacturer
- roll lot number
- blanket style
- Color stripe woven into the fabric of the blanket—these color stripes identify the manufacturer and indicate the direction in which the blanket should be mounted on the cylinder. The fabric stripe should go around the cylinder, not across.
- Bars or end treatments—generally your blanket supplier can provide blankets with bars already attached. These bars should be neatly and securely attached to each end of the blanket without any excess epoxy or residue on the surface or fabric.If your blankets require holes or have to be punched, these holes should also be neat and aligned properly on the ends of the blanket. For all blankets, squareness is important. Be sure to check all blankets to make sure they are cut properly.
- Rubber surface color—the pigment used to produce different colors of printing blankets usually does not affect the performance of the blanket. However, extreme color variation within an individual blanket or blankets of the same style but from a different roll lot number may indicate aged or inferior quality blankets. Slight color variations are common with all rubber products, but if the variation is significant, it is recommended you check with your supplier before using the blanket. Although the color of the rubber, for the most part, is irrelevant to the performance of the blanket, certain surface colors can aid the printer in reverse image inspection and troubleshooting.
- Edge Sealants—at the request of the customer, a water and solvent resistant coating can be applied to the edges of the blanket. This will help keep moisture from penetrating the carcass of the blanket and prevent swelling and delamination. The sealant should be applied only to the edges of the blanket with no excess on the surface or fabric side.