By Lori Lord, Rocheux International

Have you ever walked into your local home improvement store, strolled up to the paint counter and told the clerk you need a gallon of white paint? The clerk tilted his head, tried to hide his smirk and escorted you over to the wall of paint chips where he politely asked, "OK…which white?" You stood there staring at hundreds of white chips muttering to yourself, "White is white, isn't it?"

Well, white isn't that simple. As in paint colors, there are innumerable shades and variations of white that can be considered when choosing a PVC core stock material.

To help determine which white is the right one for you, there are several things to consider. The most important is the performance of your inks. The same ink will react differently on various substrates. Be consistent in your choice of ink and your method of application. Develop and maintain good communication with your ink suppliers and keep them abreast of changes you make in your process, whether it be substrate or drying related. Knowing about changes ahead of time can save much time if and when issues in your manufacturing process arise.

Another important aspect in determining the right white is to decide how your production people handle raw materials. If you are buying core stock from multiple suppliers, this is especially critical. There are two different approaches to this along with variations of each method. As in any process, too, there are pros and cons to each one.

One approach is to choose a color standard and require that all of your core stock suppliers produce material to that standard. If this is your method of choice, you will need to specify not only the target color standard, but also a variance level that is acceptable. When establishing a variance level, you need to coordinate with your vendors on how to measure color. This strategy requires little input on the part of your production personnel because the white color will be the same regardless of which vendor is supplying the core stock. As a result, the inks and processing of the material can remain relatively similar from job to job.

An opposite approach to color choice is one where different whites are accepted from multiple suppliers. In this case, it is essential that your production personnel correctly identify which manufacturer's sheets they are using for each job. Inks, and potentially processing conditions, can differ dramatically depending on the shade of the white core stock. This method places greater responsibility on your production operators than the other method. Proper use of vendor inventory part numbers will help to avoid errors. This responsibility can be also lessened by some of the more sophisticated equipment that exists which can have settings programmed to help determine the proper printing parameters for the core stock. This type of program requires a strong inventory management process so that raw materials are quickly and easily identifiable to your operators. The process doesn't have to be complex - a simple idea is to paint a colored stripe on the cross section of the sheet stack. Associate one stripe color to each supplier and you have a quick, visual reference for your operators.

Of course, these aren't the only options. They are just different philosophies. You can choose to adopt a process that is somewhere between the two or one that incorporates aspects of both.
However, regardless of which method you choose, demand that your core stock suppliers provide you with product that is consistent in color lot after lot. Color consistency is the key to successful repetitive runs through your plant.

The surface of the core stock can also play a major role in the overall printability of the material. Most PVC manufacturers offer a variety of surfaces including matte/matte, matte/gloss, and gloss/gloss. Some even offer variations of each of these. Talk to your suppliers when deciding on a surface. They can provide samples and will work with you to determine which of their products will work best for your applications. Be sure to relate to your vendors which methods and machines you are using to test surfaces.

Be wary, however, of the differences in surfaces between core stock suppliers. One supplier's matte/matte may not necessarily exactly match their competitors' matte/matte surface. Therefore, it is also important to discuss other surface aspects such as Ra values (surface roughness) and even peak counts. Dyne level testing for ink receptivity is important, too. Test each surface you are considering using with each of your inks as well.

Once you have worked with your core stock suppliers and identified which color and surface are going to work best for you, don't be afraid to require the supplier to provide you with certifications on each shipment. These certifications can be done on each lot and should specify the testing that was completed and report the results obtained. This can help to reduce the amount of incoming quality inspection that you would need to do each time a shipment is received.

As important as location is to real estate, so is consistency in the production of white core stock. So, when it comes to color and surface, remember the three most important things: consistency, consistency, consistency.