Thursday, September 17, 2009

Oil & Water

Have you ever noticed how certain recipes always ask you to pat your poultry or fish down dry after rinsing it with water? We do this exercise but why? The reason for this is because oil and water just don't mix. If you wash a piece of chicken by running it through water and do not dry the chicken before adding oil, the water will repel the oil. If you pat the chicken dry it will be more receptive to absorbing the oil and you will achieve a nice coating.

This same concept, that oil and water do not mix, is the main principle behind offset printing. The poultry in printing would be your plate. Not to be confused with something you put your food on, a plate is a metal sheet that attaches to a cylinder on press.

The plate contains the actual dotted image that will be printed for each color we use (CMYK). The plate’s image area contains chemicals that are highly receptive to oil based inks but naturally repel water. When we attach the plate to the cylinder on the offset press, the plate will rotate and come into contact with dampening rollers (water) and then ink rollers (oil). The water dampens the plate and when this happens the oil receptive image area will repel the water, while the non-image area will receive the water. When the plate comes into contact with the oil based ink, the ink will only adhere to the oil receptive image area and it can not adhere to the non-image area because that part of the plate is coated with water. Because plates do not transfer the cleanest image to a sheet of paper, the inked image is then transferred (or "offset") from the plate to a durable rubber blanket that conforms to the surfaces of all types of paper stocks. The blanket prints the image to the paper completing the process of offset printing.

Monday, September 14, 2009

The Oven Part 2: Web Growth

In the world of web printing, the web roll is pulled through an oven to dry the ink to the paper. This is done to take advantage of in-line finishing that a web press is capable of. As the form leaves the oven, it is completely dry and ready to be folded. While this creates efficiencies and cost savings, it can also result in an unattractive phenomenon called web growth.

Have you ever seen a catalog that looks like the cover was trimmed about 1/32 short of the text? This is a result of a sheetfed-printed cover binding with web-printed text. A few days after binding the two together, the text will physically expand. What has actually happened is that the text has swelled slightly after absorbing moisture from the air. The OVEN is the culprit. When the text is pulled through the oven to dry the ink, the moisture already in the paper is literally cooked or sucked out. For a consistent product and ease of handling, the folded text signatures are then baled together tightly. They remain air tight right up until the point that the bales are cut and the signatures are bound together and trimmed. After the product is completely bound, is the first time the text is exposed to moisture in the air. Over the course of a few days, the moisture creeps back into the paper and web growth begins.

What can you do to combat this? The best remedy is to print the cover and the text on the same press, however this often isn't the most economical solution. Another solution is to trim the books post web growth, but again this adds time and costs. Perhaps the only real remedy is to accept web growth is possible and thus design your piece to eliminate how much it stands out. Placing a coordinating color on the outside bleed edge of the first text page can eliminate how noticeable it is.

The Oven - Part 1: Cooking Tips

While dishes can be used in a microwave, avoid placing dishes that have silver or gold trim (metal) in the microwave.

Before starting any meal where the oven is in use, the first step should always be pre-heating.

Convection ovens cook much faster and more evenly. Because of this, it is usually necessary to cook at a lower temperature or for less time than the recipe asks for (Most restaurants use convection ovens).

Don't open the oven door too often when cooking. Each time you do, the oven temperature decreases at least 10-20 degrees.

If you like you're meats rare, use an oven. It is much easier to control the internal temperature of the meat and not over cook than it is by using a grill or stove-top grill pan.

Set your oven at a very low temperature and use as a warmer for your plates so your warm food doesn't get cold by dinner time. This will also help guard off bacteria that will infect the food as it cools. (WARNING - Do this with caution as a plate can crack if it gets too hot. It doesn't take more than a minute or two to warm the plate.)