How to Solve Blurry and Uneven Prints After Screen Printing?

by Kevin Cook| in Printing Guide on March 26, 2021 5493 /

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Last Updated on: 6th November 2024, 06:25 pm

There are several factors that can influence a print ‘s quality. From the squeegee to the appropriate cure temperature, any piece of screen-printing equipment used will influence a job ‘s outcome.

Think of the equipment as tools; when used correctly, the outcome will be positive.

First, it’s important to maintain a clean and organized facility when screen printing. You may not think it has any effect on your prints’ outcome, but it does.

You can tell if a shop meets this standard just by its appearance from the reception area to the back door. If the employees care about the plants in front of the building, then they care about the boxes of finished garments being shipped.

1. Prints Become Blurry and Uneven:

Inadequate removal can leave marks such as a mesh mark on the printout or cause the image to blur.

The larger the image is printed, the more pronounced the blur can become if off-contact is not set properly.

Also, the lower the screen mesh’s tension, the more off-contact will be needed to get the screen to peel off the substrate, which can add to the blurriness.

2. Screen Tension:

If your screens are very loose, get them restretched as soon as possible. Your local dealer can help you with this. In the meantime, order a few new screens of your favorite mesh counts.

Simply put, printing is much simpler with small windows. Registration and off-contact magically become less of a problem as well. Just make sure that all the screens being used for a specific print have the same or identical stress values.

For example, if a five-color job’s registration is off, check to see if all the screens are in the same stress range. If one is lower than the others, it is probably that screen that’s causing the registration issue.

3. Shirts shift from Pallet:

It can be frustrating when a shirt shifts as the pallets move between screens when you ‘re in the middle of printing design. It may mean you have to start a job again from the beginning. Investigate the adhesives that are provided by industry suppliers.

Some are sprayed or squeezed out of a bottle, while others come in a bucket and can be spread onto the pallet.

Do some research early in your garment-decorating career to find the right kind for your store. Most water-based adhesives are less affected by the flash unit ‘s heat than the aerosol ones except those that claim to be specially designed to withstand heat.

4. Ink Deposits on Prints:

Such widely ignored resources can significantly impact print quality. When you are printing on a manual press, remember to properly flood the screen before each print.

The flooding action pushes the ink into the area that is to be printed and does half the work. You can just add the ink on the shirt when you finally print.

If you did not flood the screen before each print, otherwise the print stroke will be pressured and the ink can be pushed into the fabric, and money, income and profits can be lost.

Every automatic screen-printing machine floods the screen each time before the squeegee prints

5. Squeegee should be sharp:

Additionally, maintain a sharp squeegee edge. It helps to cut or shear the ink, which makes it easier to remove from the paper.

It will make it easier for the ink to clear the screen and make it look rough if the edge is scratched or rounded. Replace any squeegee blade that has nicks.

Keep an assortment of squeegee durometers in your shop. If you need more ink deposits on a print that lacks good coverage, switching to a softer squeegee is a quick option.

Otherwise, double-printing a color may be necessary, thus slowing production and costing more money.

6. How to minimize ink deposits?

Likewise, if less ink deposit is required, turn to a harder squeegee. Also, changing the squeegee angle will add or reduce the amount of ink being added.

For example, angling the squeegee toward the direction of the print stroke adds further ink deposit.

And always be consistent with pressure so that troubleshooting will be easier when a print goes awry

7. Emulsion Stencil Quality issues:

Another underappreciated part of the printing process is emulsion quality. Emulsion over mesh (EOM) is the emulsion thickness of the coated screen vs. the uncoated screen. It’s important to have a thicker emulsion deposit on the bottom of the screen’s shirt side.

When using finer mesh counts, less emulsion usually is applied, but it is important to have more emulsion added on the bottom of the screen with lower mesh counts.

It is important because extra emulsion works like a gasket to keep back the ink that is being forced through the film under pressure.

Otherwise, the ink will go anywhere, except under the holes of the screen cloth. Thanks to the ink cost, the resulting print may have messy or irregular curves.

Having a suitably thick emulsion stencil also helps eliminate mesh marks while increasing opacity.

8. Using Finer Mesh:

If there is not enough emulsion on the bottom of the screen when printing halftones and fine detail, the halftone dots may be blurred, appearing in the form of stars.screen from overheating.

It ensures the screen peels away from the print as the squeegee moves over, thereby reducing contact with the heated document.

9. Ink Cracking Issues:

Using too much and too little will damage your print. The normal, industry-agreed-upon curing temperature and time are 320˚F for one minute.

This is a guideline and doesn’t mean you can’t cure a four-color (halftone) process design at 360˚F for 45 seconds.

The thicker the ink deposit, the longer it takes to cure. Some special inks can cure at lower temperatures, though printers must use caution when working with them. How can you be assured ink has cured sufficiently?

The general rule is to stretch the print after the dryer has been removed and cooled. If the print cracks, it won’t be cured. Be careful not to stretch your print until it cracks.

Instead, take a 1-inch-wide print and stretch it to a maximum of 2 inches to see if it cracks. To make sure all the ink has healed twice, wash your clothes.

10. Ink Passing Through the Shirt:

If you see ink being squeezed through to the inside of a shirt, then there is too much pressure being applied to the screen.

That the ink is too thin, the squeegee is too rough, too much pressure is applied or the substrate fabric’s weave is too open.

Always test squeegee pressure by lowering it to where it almost won’t print, then add just enough to where it prints just right with visible details and even coverage and then stop. Look at the garment’s underside and you can see far less ink.

11. Drying of Ink on the Screen:

Printers often refer to ink drying on the screen when it becomes hard and clog the screen mesh’s open parts.
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This is usually caused by over-heat, most likely following the blinking process. If you do not allow the ink to refresh after you blink, the screen can partly cure the ink it contains on the top of the heated print, thus blocking the mesh..

The proper removal will also help avoid overheating of the ink on the screen. It means that the screen is pulled as the squeegee moves over the print, reducing contact with the heated print.

12. Dye-migration:

Typically only polyester or polyester blended clothing is the subject of dye migration. When the polyester fabric is dyed, it is set, cured, or dried between 280˚F and 300˚F.

If a screen printer cures ink at 320 ° CF, the coloring is then produced at a higher temperature than the polyester dye healing temperature.

Dye migration can happen when dryer settings aren’t reset from a previous job involving cotton shirts, which can involve temperatures between 330˚F and 340˚F.

The white ink in a design can turn pink on red fabric or gray on dark fabric, or perhaps other colors due to excessive dyeing.

Sublimated camouflage fabrics are prone to heavy dye migration, making them some of the worst fabrics for printing, so be cautious.

13. How to avoid Dye-Migration?

Use a low-bleed, low-curing base ink or low-curing additive to prevent color migration. When printing on fabrics known to bleed.

Seek to remove the dye with different gray or black blocking inks. Gray or black blockers need to be overprinted with white if other colors will be printed on top.

Conclusion:

When you take care of your screen printing tools and are consistent with your screening methods, mesh tension control and dryer temperature checks, etc., your prints will be better looked at.

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