Envelopes can be printed in four different ways: Offset, Flexographic, Litho and Digital.
The majority of envelopes are printed on an offset press; the most popular of which are the “Jet” presses made by the Halm Corporation. Those are the presses used by most envelope companies and some printers. The Jet press is a sturdy workhorse that feeds envelopes up to 12 x 15 ½ in size and prints at speeds up to 30,000 per hour in some cases. Most Jet presses print up to two colors and can perfect (print on both sides) in the same number of colors. However, there is a 4 color Jet which prints process or spot colors on envelopes with excellent quality.
Probably the second most common way envelopes are printed is flexographically. (I say probably because I have no hard data on this. If anyone out there has evidence to the contrary, I’d be very interested). Flexographic or as it’s commonly referred to, flexo printing is generally done in-line as the envelope is manufactured. Unlike offset printing which uses a metal printing plate, flexo printing uses a hard plastic, photo-polymer plate. Flexo printing technology has come a long way in the past 20 to 30 years. It used to be done with soft rubber plates and used only for the most basic printing like, say a business reply envelope. However, these days so-called enhanced flexo machines routinely print full coverage 4 color process envelopes with great results.
The next most popular way to print envelopes is on flat sheet litho presses. This requires a two step process of first printing on the sheets and then converting the sheets into envelopes. As an envelope converter, Elite Envelope regularly advises customers on when this might be necessary. It is a more expensive proposition than simply printing an already converted envelope on a Jet press but yields the best quality printing because of the size and capabilities of the equipment.
Lastly envelopes are sometimes printed in small quantities on digital copiers or presses. These machines can only print in process colors so they are not workable for a simple one or two color job. Also, the economics only make them a good choice if the quantities required are small. Generally anything over 2,500 doesn’t make sense to do digitally at least as far as envelopes are concerned. Not all digital presses can easily accommodate envelopes. Some of the newer models include this feature and work quite well.
So back to the question: What IS the best way to print a 4 color envelope? Well, the simple answer is it’s based on three main factors: quantity, quality and coverage or a combination of the three. I’ll break this all down for you in next week’s post. In the meantime, your comments are always most welcome!