01 Aug 7 Steps to Resolving Registration Problems
Registration can be one of the most nerve wreaking tasks in the screenprinting technologies for anyone who has to print multiple colors or produce a print that must register on the substrate perfectly with each print. You may be surprised that the downtime you experience trying to line up that job that did not want to cooperate is really not necessary. With a little knowledge and taking the right steps, you can all but eliminate registration problems from your life.
But, wait, there’s more! While you were attempting to register that job, there was a lot more going on that was causing you even more financial loss. The very things that caused the registration problem are decreasing not only your productivity but also a loss of quality. You may have an increase of dot gain or dot loss that will rampant from one substrate to another. The ink deposit will be uneven across the image plane and will result in loss of color consistency.
The most likely problem causing misregistration is that it could be that your press is out of parallel. You are not alone my friend, many printers, if not most, suffer from this same problem. In the many shops that I visit, I have yet to find a press that is properly setup. Most screenprinters buy into the myth of “leveling the press” with bubble level. While this may work on a single station, clam-shell, press, it will never work well on a multi-head press. It only takes a moment of thought to realize that a bubble level will not bring the press into a parallel and geometric plane. The principle of leveling is to obtain a horizontal line of sight with respect to which vertical distances of the points above or below this line of sight are found. While leveling may be useful in hanging a painting in your home, or to keep objects from rolling off a table, think how this affects the press. Sure, you don’t want the ink to flow to one side of the screen, but how will this affect registration? No, you need to bring the print head, fill blade, squeegee, screen, and press bed (or platens) into a parallel and geometric plane with one another so that they are in perfect registration with one another.
The most important solution is to bring your press into a parallel and geometric plane. While many of the variables we are faced with are unavoidable or simply beyond what we can fix given the constraints of time and money, bringing your press into a parallel and geometric plane is certainly within anyone’s reach.
When having registration problems, you need to first look at several variables, and decide which are causing the issue. Once you know where the problem lies, then fix that problem so you will not be continuously plagued with problems.
You don’t have to work that hard to achieve excellent quality and increased productivity. All you need is to gain knowledge and put that knowledge to work for you.
Here are 7 Steps to Resolving Registration Problems
1. You must begin with films that are in register. If you are printing with roll film, registration could be an issue caused by drag from the weight of the roll. Heat and humidity could be creating a shift in the film positive.
2. You should have sufficient tension on the mesh that it won’t move during printing. Tension to the mesh manufacturers suggested minimum tension level.
3. The exposure unit glass must be flat. The heat from the exposure will cause the glass to sag in the middle and if so, it should be replaced. Check it with thread stretched from one corner to the opposite corner.
4. The press must be capable of holding the screens tightly in place. Side clamps on a manual press are always a necessity for properly securing frames in place.
5. The print head must be held tightly at the registration gate. It can usually be adjusted or the Teflon rollers may need to be replaced.
6. All platens should be on a plane with one another. When someone touches the platen, with even a slight force it could be tilted to one side. This causes the image on that screen to travel further to reach the platen on that corner and thus creates a problem. While you are at it, check the plane of each platen individually. Any platen that is bowled or bowed should be replaced immediately.
7. Since screenprinting is an off-contact method of printing, the mesh must be moved down to touch the substrate. If the screen is not on a geometric plane with the platens, then the mesh will be moved more in the direction in which it is further from the platen. This will throw the registration in that cover off.
There is obviously more to registration than explained in an article, and if you want to learn more you should read the book, Parallelism and Geometric Plane. I hope this helps those with registration problems come to a quicker solution.