Choose the right cliché for your pad printing business

The following list describes the different types of clichés currently available:

Polymer (it is important to note that it has many different qualities)

1. One exposure (Plate has the same etching depths usually 30 microns)
2. Double exposure (Depth can be changed, see later explanation)

Steel

1. Thin steel (Flexible about 0.050 cm thick)
2. Thick steel (0.6 to about 1.27 cm)

My personal experience with pad printing and with the old style of using a knife and with the new closed style with a ceramic ring. I mention this because each has certain specifics when it comes to choosing clichés.

When choosing clichés, the following points should be considered:

1. Print size.
2. The amount of color coverage from the largest to the smallest area.
3. 1. Thickness or required opacity of paint.

​The first consideration is usually the price (this is not my opinion), which refers to the size of the job in the pad printing for which the cliché is chosen. If you use an open system, it is much faster to change more jobs when polymers are used. So short jobs (smaller series) are more suitable for polymer clichés both because of the price and because of the quick start of a new business.

Any printing job that exceeds 10,000 cycles typically consumes one or more polymers, and if you can't make your own clichés at home, you'll probably use thin steel or thick steel clichés to prevent the printing process from interrupting. You can also order more than one cliché as a backup, but please consider rejection, as well as downtime, which will quickly drain the savings you have made by ordering cheaper polymer clichés. The use of a polymer cliche requires the selection of a more favorable (usually more flexible) knife to prevent the brittle surface of the polymer cliche from cracking.

This flexible knife also tends to sink more easily into parts of the image that are parallel to the knife or larger parts of the paint in the image, causing faded areas. This is usually called capture. In most cases, even more consecutive prints will not eliminate the problem, and if rotating the image does not solve the problem, you will have to reach for a firmer knife. Using a firmer knife usually requires the use of a steel plate with a grid in larger areas to prevent large grip and to contain a larger layer of paint.

Raster film basics:

Engraved areas, instead of being large open spaces, have small peaks that are created by exposing clichés with raster film (lines per cm and the percentage can be as low as 70 lines 70% or even as high as 300 lines 90%). The engraved surface takes on the appearance of a crater with tiny evenly spaced protrusions at the top.

Raster appearance during the second exposure

These bumps or peaks serve 4 purposes:

1. Help with knife support and eliminate grip that may occur.
2. It helps to reduce the surface tension in the paint and allows an even layer of paint to be taken over by the tampon.
3. Prevents color from coming out of the engraved part of the image during the knife transition process.
4. Prevents excessive color from traveling while pressing the tampon in the image download position.

The old style of the open system is suitable for steel clichés and in many cases they are used exclusively with steel clichés and using this system on polymer clichés requires some finesse and experience. The use of thick calculus clichés is not necessary with a ceramic ring in a closed system, in fact it can be problematic if the cliché is not perfectly flat.

The latest style of color storage (at least the one with high quality ceramic rings) has proven to be good for the use of polymer clichés in the case of printing less than 100,000 cycles. In cases when it exceeds 100,000 cycles, the use of thin steel clichés is recommended because these clichés are relatively cheap and will easily withstand series up to 1,000,000 cycles.

In my experience, the problem of capturing too much paint from a larger surface when using a ceramic ring on polymer clichés can occur but very rarely. When etching clichés if extreme care is used and if double etching is used on high quality polymers these problems do not arise. These problems of removing more color from larger areas of the engraved image on the cliché are not as pronounced in the closed system with ceramic rings as in the open system and the use of a knife. This is due to the fact that the ceramic ring will not bend into larger recesses in the engraved image. Any occurrence of this irregularity occurs if the material bends inside the cliché. For this it is obvious that very thin flexible clichés will create more than less flexible heavier polymer or thin steel clichés.

Double exposure of polymers

Double exposure of polymer with raster film on engraved areas in many cases I have seen the elimination of holes using this type of cliché. Double-exposed clichés also allow buffer machines to make indentations that are best suited for a given application, such as printing on wood or leather will always require deeper engraved clichés than when printing on less transparent materials, such as most plastic or glass.

Single exposure of polymers

One exposure of a polymer has only one advantage over double exposure to clichés, and that is if you have very fine image details that tend to be lost due to another exposure. Single exposure of clichés is usually more expensive and is recommended only when the image consists of very fine details. If you use one exposure with a large image, the chances of color fading on a larger surface will occur.

Choosing the right cliché for printing becomes less of a problem if you are equipped with your own cliché making equipment so you can always replace worn or damaged clichés.