Why Screen Printing Registration Marks Reduce Mistakes

One of the first things I learned when printing multiple colored designs, was screen separations and screen printing registration.  

Why screen printing registration is so important?  Screen printing registration is a process where you align multiple screens onto a screen press.  In order to get an accurate alignment, you need to use registration marks. Without registration, your design position may not print as desired on all colors.

You know how many t-shirts I went through with the almost exact registration and it still was off?  A lot, but then again I was using junk t-shirts to test on.

I re-used the same few t-shirts over and over until they have no spots left to print on.  Follow some of the tips and don’t waste perfectly good t-shirt blanks and time.

So let’s go over what registration marks are.  Imagine you have a 2 color design you wanted to be printed on a t-shirt.  This will require 2 separate screens for each of the colors you are using.  

So you will prepare the 2 screens with emulsion and this is the part where registration starts.  After the screens have dried you will print out the artwork on transparencies in solid black ink. This is also called a film positive.  

These films will have 2-3 crosshair target icons or a symbol of your choice to line up with each other. If all 3 line up on the platen and the screen then everything is straight.

You will proceed to tape the film positive onto the outside of the screen in a mirror image orientation.  When you look from the inside of the screen where the ink will be pushed through it will appear right side up.

Film Alignment On Screen Printing Screen

The first tip I would use is to put your film positive onto the platen.  The platen is the board that is attached to the arm of the screen press where the t-shirt draped onto.  You can also call it sleeving it onto the plate even though it is the entire t-shirt.

You should draw grid lines on the platen to help with future project alignment.  A few helpful lines are a line down the center, a line which is about 3-4 finger widths down from the neck seam, a left chest design line, and a center back design.

A center back design will have a different height than a center from design because the seam starts lower on a front chest.  Usually, you will be working with screens of the same dimensions for most jobs. The sizes on those can vary.

So once the film positive is down on the platen, clamp in a screen onto the press.  Lower the screen onto the platen. Then make a note of where on the screen the artwork should be positioned, before exposing the screen.  

Making sure you have enough room on the top of the design of the screen, for the ink to be pushed and pulled from.

Exposing The Screen

After the film positive is taped onto the screen you will then put it in the exposure unit.  You will expose the emulsion to UV light which will cause it to harden.

The area which is blocked out by the film positive will not be exposed.  After a few minutes, depending on your emulsions specifications you will remove the film positive and proceed to a wash station.

At the wash station, you will spray out the area of the emulsion which was not exposed.  This will then leave a clear section of the mesh where the ink will go through.

Let the screen dry to the touch and it is now ready to be used.  

Micro Registration On Your Screen Printing Press

You will tape the transparency to the platen in position as stated before.  Now you will line up the design and registration marks on the screen to the film positive on the platen.  Now you are sure to have a straight design.

There is a feature on some screen presses called micro registration.  This gives the ability to make minor adjustments to the orientation of the screen if needed.  

It is a more accurate system with this feature so I do recommend it. So after you lock in your screen to the head, pull it down in position.  Then check if it lines up with your film positive and adjust accordingly. Taking into account if it is centered as well as straight.

If the first screen lines up, continue with the next color if there is one and so on.  Make sure to check your off contact which should be about 1/8th of an inch.

Preventing Print Errors

Now it is time to put spray tack down on the platten followed by a t-shirt. We do this so the t-shirt does not shift during the printing process.  Remember before doing a test print, work the ink before pushing the ink through the screen.

The reasoning is to make sure it is the correct consistency throughout.  Now everything is lined up, it’s time to stroke. Do this single print run as you would a final print run.

If you design is multiple colors do a print, flash, print.  Putting your t-shirt under a flash dryer is known as flashing your t-shirt.  We are merely making the ink dry to the touch, so the next layer of ink can go down.

Once complete check your design if everything looks good you are ready to start the final run.  If not you see which screen is off and you will adjust.

Printing On Dark Garments

Remember with dark t-shirts you will need a white ink underbase.  An underbase is the first coat of white ink on a dark garment to help the color pop.  The underbase goes beneath every single color in the design.

During the design phase, the underbase is a slight stroke smaller by about 2 pixels.  The reason for this is because you don’t want the underbase to show outside of the top layer of ink.

Screen Printing Screens

Your print quality is very dependent upon your screen registration.  If one screen is off an entire design will be ruined. As you can see there are multiple areas where if a step is not completed precisely, there will be a problem.

Another problem you may face is the condition of your screens.  It is not uncommon for screens to be reused. Some screens may warp over time. Some screens are wood and some are aluminum.

Another factor is the mesh. Mesh does get warned down after repetitive strokes in the same areas continuously.  If mesh tightness is off your design may be as well.

Related Questions

What are the common silk screen frame sizes?

The common outside diameter frame sizes are 16” X 20,”  18” X 20,” 20” X 24,” and 23” X 31.”

What are the different screen printing mesh counts?

Mesh counts on mesh screens are measured by how many threads there are per square inch.  A higher mesh count has finer holes on the screen which create more detail when ink is pushed through the screen’s mesh.  Because there are more threads less ink will be deposited on the garment.