by Milt Vine
To mylar or not to mylar. When it comes to tabbing, the question-as it was in Hamlet's case-is not so easily answered. There are a number of factors to consider before determining whether or not a protective coating should be used. And, if so, which is the best for the job?
End use is a good place to start. Are the tabs for a perfect- or mechanical-bound book? How often and under what conditions will the publication be used? How many tabs will be required? Are aesthetics important?
Since I covered types of tabs in my last column, I'll limit this discussion to the whens and why fors of tab coatings; specifically, mylar reinforcement of diecut tabs and the spine of the tab sheets.
Plain Tabs. Plain tabbing simply refers to a tab without any type of reinforcement. These are usually printed and used in proposals, reports, legal exhibit dividers and file folders; in other words, publications that require dividers, but don't demand the durability that a coating provides.
But what if your client's product does need to withstand heavy usage? Consider using mylar to strengthen them.
What is Mylar? Mylar is a transparent polyester film made in extremely thin sheets. Similar to cellophane wrap but much, much stronger, it is applied over pre-printed tabs or adhered in strips to the binding edge of sheets for reinforcement. It prevents the tabs from curling and smudging before their time or pages from tearing out. Mylar comes in 16 colors, including clear.
Tab sets can use a single color mylar or any combination of colors. In fact, color-coding is one of mylar's popular features. For instance, one of my customers prints an office supply catalog. It is divided by category (writing instruments, paper & copier supplies, computer supplies, furniture, etc.). Though the catalog has an index, and the top of each page identifies the section, users rarely refer to either. Instead, they match the colored tab in the table of contents with the colored tab in the catalog body, and flip to the desired section in seconds.
In short, color-coding improves the readability of manuals, reports and catalogs by dividing information into easily-identifiable sections for quick reference.
Mylar Reinforcement for Tabs. Before deciding to use mylar reinforcements, make sure that your client's choice of tab configuration can be mylar coated by machine. Your bindery should have equipment that automatically applies mylar to tabs in standard and overlapping tab configurations, which can save your client substantial hand-application costs. A brief refresher from last month's column: Standard tabs are those that are all the same size and evenly spaced in a row, or bank. Overlapping tabs are all the same size and evenly overlap in a number of banks.
Only clear, not colored, mylar can be applied by machine on cover tabs (tabs that are the entire length of the divider sheet.) And shingle tabs-those that overlap and increase in size as they progress from top to bottom-cannot be machine-mylared at all.
Mylar Reinforcement for Printed Sheets. Because tabs are primarily used in mechanical-bound books, including 3-ring notebooks, reinforcing the spine with mylar is commonplace. The stress caused by the binding mechanism often causes pages to rip from the binding. Usually a 1/2" or 3/4" strip of mylar along the binding edge of a sheet is adequate protection. After the mylar is applied to sheets, they are then punched or drilled for binding.
Ink and Varnish Considerations. Like any other finishing process, mylar application has certain rules to follow for best results. During the automated mylar application process, sheets pass through a series of heated rollers which fuse the mylar onto the sheet and position the sheet for cutting. Then the equipment cuts the tab with a tooled die.
Because of the heat, wax-based ink or varnish is likely to smear during this process. Therefore, these are to be avoided. Also, be aware that some inks are more prone to scuffing and marking when put through finishing processes. These, too, should be used with caution.
Also, make sure your sheets are dry before sending them to your bindery for mylar reinforcement. Some customers add a little cobalt dryer to inks over which mylar is to be applied.
Lastly, avoid heavily-textured paper when specifying mylar. The uneven surface can cause unsightly air pockets under the mylar.
Working closely with your bindery on tabbing projects will save you headaches and your clients costly surprises. Before finalizing specifications on a tabbing job, ask your bindery to run a free test to make sure ink won't smear, color mylar tabs are consistent and paper stock won't alter the expected outcome.
Milt Vine is president of Seattle Bindery, a post-production house specializing in
index tabbing in addition to providing folding, stitching, perfect binding, scoring ,
perforating and trimming services for the trade. You can reach Milt at 206/682-2558.
© 1996, Seattle Bindery. Reprinted from Northwest Trader, July 1996.