askralph

Dan Asked Ralph –

We have designed a corrugated box for a customer that features a QR code.  The Box manufactured is not sure the QR code integrity will hold up (so it will be scannable) with flexographic printing.  It is printing in one color (black) over a white base ink printed on the corrugated stock.

Do you have any advice or experience when printing QR codes on corrugated boxes?    Thanks.

—

I turned to my good network friend George Cusdin, President of Flexographic Printing Services.  He offers some very good advice below. One other thing Dan, don’t forget to put a non gloss varnish coat over the Quick Response Code. – Ralph

“There are upwards of 50 versions of Quick Response codes such as: ScanLife EZcode, MicroSoft TAG and the real brand “QR code”. They are the 2 Dimensional codes that hold up to 1000 times more info than the traditional single dimensional bar code.

The code is about 1 inch to 1.5 inches square and can be scanned using the modern cell phone, which then ‘passes the URL then can display the product info from the manufacturers web site.

The individual square blocks of code are easier to print than the traditional bar code because they are about 1/25 inches square (3 time the width of the narrowest of the bar code elements) and the white spaces between code elements are the same width. Also, because the elements are evenly spaced, they are far more readable than conventional bar codes.

As with bar codes, the printable resolution of the printing of the process determines the printed size of the code.

With  corrugated post print a 1.5inch QR code with a 25 x 25 matrix (holding 4,296 alpha-numeric characters)  should be printable (and scannable) using any modern post-print flexo press.

When printing a QR code using web flexo that can easily print around 120lpi screen values, ‘dot gain’ (the increase in spot size due to impression and ink spread) is fairly minimal when printing the relatively large elements in a QR code.

However, with regular flexo post-print the typical line screen is between 50 and 85lpi, the ‘dot gain’ is substantial and therefore must be compensated for by making the dot on the printing plate smaller.

Similarly, spot-size compensation must be made when printing QR codes on a flexo corrugated post-print press and I have a method of applying this compensation.” — George Cusdin, Flexographic Printing Services

This entry was posted on March 17, 2011 at 4:36 pm and is filed under Finishing/Converting, Printing. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.