Cast aside outdated information about sign making vinyl

Simple diagram of making Calendered Vinyl

Simple diagram showing calendered vinyl process

You can’t lose money investing in a “dot com” startup! Put all of your money in AOL and you’ll be a millionaire within five years!

The only viable outdoor printer for small sign shops is a thermal resin product like a Gerber Edge, or Roland ColorCamm.

Obviously none of the above is true. It’s dangerously outdated, 20th century advice.  Would you listen to a stock broker whose recommendations are based on ten year old market conditions? Of course not. What’s this got to do with running a sign business?

Believe it or not, there are still people in our industry giving advice based on the conditions of the late 90s. You see this most often when you ask people about the difference between cast and calendered vinyl.

Back in the days of MS-Dos and floppy discs, there was a vast difference between the appearance and performance of cast and calendered graphic marking films. Cast vinyl had high gloss levels producing a paint-like finish that would last five to eight years outdoors. The casting process gave it levels of dimensional stability and conformability far superior to those of calendered film. Why is it important for you and your staff to understand the differences? If you’re still bidding every job with cast vinyl, your price is going to be too high much of the time. That means you’re more likely to lose bids, or win them with much narrower margins. Neither is a sound business practice.

Quick Reivew: How they’re made

Calendered vinyl is made by running a paste of pvc, plasticizers, and resin through a series of rollers (calenders) that successively squeeze the mixture down to the desired thickness; generally 3 mil (.003”). See fig 1. Since calendered film is changing shape as it’s made, it tends to be inherently unstable. Its molecular memory results in lower levels of dimensional stability. This results in shrinkage, cracking and peeling over time.

Simple diagram showing cast vinyl processCast vinyl is made by pouring a liquid mixture including solvents, plasticizers, and resins on to moving web and running it through an oven. The solvents evaporate in the oven leaving behind a thin film-generally 2mil (.002”). See fig. 2. Adding colors is less expensive when casting, so cast vinyls tend to have a broader palette than calendered films.  Since cast film is kept at a constant thickness as it’s manufactured, it has a higher degrees of conformability and dimensional stability.

It’s not your father’s calendered vinyl

Consequently, most 20th century calendered vinyls had visibly lower gloss levels. More importantly, due to the simple, monomeric PVC from which they were made, they were only conformable enough to apply to flat surfaces, and would shrink, crack, and/or peel after a short time outdoors. The standard outdoor life was six months to three years.

Fast forward to 2010. What’s changed? Cast vinyl has gotten a little better. Typical outdoor ratings for cast films now exceed nine years. ORACAL’s new 951 claims an outdoor life of up to twelve years for black and white, and a decade for transparent and colors. Avery Ultimate Cast 900 series is now rated for up to nine years outdoors.

While cast vinyls have gotten a little better, calendered film have gotten much better. In 1996 ORACAL USA introduced 651 to the market. 651 was a dramatically different approach to manufacturing calendered film. Instead of a low gloss, 3 mil, monomeric face stock, 651 came to market as a thin, glossy, 2.5 mil, polymeric film with exceptional conformability, and levels of dimensional stability unheard of in a calendered film. The result was an affordable vinyl with gloss and outdoor durability approaching that of a cast film, but for half the cost.

To further reduce the need to pay extra for cast vinyl, ORACAL launched 651 with 60 color choices; almost twice that of the average calendered film of that time. 651 was launched with the bold claim of an outdoor rating of at least four years. Today, as sign makers around the world have installed it on a myriad of substrates, real world experience has increased that number to an official rating of six years outdoors. 651 is now marketed as an “intermediate” film, designating it as an option bridging the gap between the economy of a calendered film and the performance of cast.  Because of that ground-breaking product, other manufacturers stepped up their games. Today, the vast majority of calendered films have paint-like gloss levels and outdoor durability in the four to six year range. Avery’s entry level 500 Promo Calendered vinyl matches the gloss rating of its 900 Ultimate cast product and is rated for up to four years. LG Hi-Cal 6000 tops our charts with a seven year outdoor rating for black & white.

So why do I still need cast vinyl?

So what’s the difference between cast and calendered vinyl in the year 2010? As good as intermediate calendered films are, they’re still not as conformable as cast products. Consequently, they’re still not recommended for application on compound curves. A simple curve is a surface that curves only in one direction; like a cylinder or the side of a panel van. A shape that curves in more than one direction– a rivet or a VW New Beetle– is a compound curve. Because of its superior conformability, cast vinyl can be applied to challenging curves. Because of its superior dimensional stability, it holds that shape very well. The most common application that still requires a cast vinyl is a vehicle wrap. When wrapping a vehicle with compound curves, you should always use cast vinyl.

For anything else, you can safely use cast or calendered, depending on your budget, color requirements, or personal preference. To help you make the right choice for a particular job, here’s a quick reference guide for economy, intermediate, and high performance films.

Quick Reference Guide: Economy to High Performance

Economy Calendered (monomeric):

  • Small color selection, lower gloss levels, low levels of conformability;
  • Suitable for flat surfaces.
  • Low levels of dimensional stability, water-based adhesives;
  • More likely to shrink, crack, or peel in outdoor settings.
  • Outdoor ratings one to four years.

Intermediate Calendered (polymeric):

  • Broader color selection, higher gloss levels, better conformability;
  • Suitable for flat surfaces and simple curves.
  • Better dimensional stability, solvent adhesives;
  • Better resistance to shrinking, cracking, or peeling in outdoor settings.
  • Outdoor ratings up to seven years.

High Performance (2 mil Cast):

  • Broadest color selection (usually 100 colors or more), best gloss levels, best conformability:
  • Suitable for application over compound curves, rivets, and corrugations.
  • Best dimensional stability, solvent adhesives
  • Best resistance to shrinking, cracking, or peeling in outdoor settings.
  • Outdoor ratings up to 12 years.