Best Practices – Knowledge Base

Color Matching

Most print jobs are done by simply loading images into the RIP software, selecting an Environment, and configuring the size & position of the print. However, certain print jobs for some clients may require precise matching of color tints, tones, and shades — for example, when printing some corporate logos with very specific color associated with a brand.

Let’s first take a very brief, very high-level look at what’s involved in general color management. Then we’ll jump into a simple visual color matching technique to avoid getting into the weeds on things like PC display color profiling and gamut complications.

Color Management Overview

Color management is a deep and wide topic that involves specialized knowledge and tools to calibrate computer displays and other input & output devices, typically to the open standards of the International Color Consortium (ICC). The calibration process results in defining and applying the device’s ICC profile.

In digital graphics design and printing, precise color management requires that an ICC profile specific to each device in use be loaded into the software used to generate visual input (such as scanners and cameras) and output (such as displays and printers).

OmniPrint has done extensive print testing to generate ICC profiles for our printers to ensure accuracy to that standard for the color gamut supported by CMYK printing when using our inks and provided RIP software. The RIP software manages the gamut mapping from RGB to CMYK. However, along with the gamut differences, consumer-level displays aren’t necessarily well calibrated to an ICC profile. These technical details can sometimes result in colors that you see on your PC screen not exactly matching the color of your prints.

Fortunately, it isn’t necessary to become a color management expert or invest in display calibration tools to get accurate color matching. (A Wikipedia article linked below gets into much more detail on color management than we’ll get into here, if you’d like to dive in.)

Now let’s take a look at a technique that makes it straightforward to visually find the specific RGB values needed in your artwork to match the hues, tints, tones, and shades in a design.

Color Chart Printing for Color Matching

The color that ultimately matters to your customers is the color that is printed on the DTG-printed garments or DTF film that you deliver to them, of course. So what could be simpler and more accurate than having a set of color “swatch” prints that demonstrate exactly what a specific color will look like when printed onto a garment?

Once you’ve printed a color chart sample you can visually compare the printed colors to the target color to find the best match. Then use that color’s RGB values in your graphics software to print that exact color.

Color Charts

Each color chart is available in two versions: one for printing onto white and another for printing onto colored fabrics.

‘AllColorCharts.zip’ is the only file that you need if you’d like all of the charts. Clicking on individual color charts will display them in your web browser. To download an individual color chart, right click on the filename then select Save link as…

Using Silicone Sheets & Kraft Paper

We use a protective sheet between the heat press upper platen and garment whenever drying pretreat, curing the ink of DTG prints, or transferring DTF prints to fabric. Different types of sheets can also result in slightly different finishes when curing ink and applying a finish press to DTF prints.

There are a variety of opinions about what type of sheet is best for different aspects of garment printing. What we’ll cover here is the usage that is in practice among our in-house print production and operator training teams.

As always, your mileage may vary so if you have a different approach that is working well for you, we don’t need to mess with success.

OmniPrint offers two types of sheets: silicone and kraft paper. Here’s how we recommend using them.

Silicone sheets

Silicone sheets are recommended primarily for drying pretreat in DTG printing.

That process is to repeatedly press at medium pressure (a setting of 4-6 on Stahl’s heat presses or 40-60 PSI) for 15-20 seconds per press until the fabric is dry.

Rotate or spin the sheet 180-degrees after the first press.
Let steam escape between each press.

Kraft paper sheets

Kraft paper sheets are recommended for curing ink in DTG printing and for the finish press (after peeling away the film) in DTF printing.

Preferences may come into play here. We like the matte finish that we get from using kraft paper at the end of our DTG and DTF processes. If you prefer a glossier finish, you may want to try using silicone sheets for finishing up your prints & transfers.

Keep in mind…

Kraft sheets are quite durable and can typically be used for dozens of presses or until they show signs of cracking. Silicone sheets should be discarded once wrinkles appear, usually after 7-8 presses, and they are discounted significantly in the OmniPrint online store when purchased a higher quantities.

DTG/DTF Laundering Instructions

Improper laundering can cause shirt-color dye migration, prematurely “age” your prints, and otherwise damage your printed garments. Please follow these simple laundering guidelines and communicate them to your clients to maximize the durability of your prints and customer satisfaction.

Turn the garment inside-out.
Wash in cold water.
Tumble dry at the lowest available temperature.
Wash with like colors, preferably the same color.
No bleach.
No dry cleaning.

Transferring a DTF Print

Transferring a finished print to a garment is simple and can be done immediately after DTF printing and curing, or up to a month later. Longer storage times may be possible if carefully stored in an air-tight container and in a climate-controlled environment.

Prepare your heat press for a DTF image transfer.

Some materials may transfer best using parameters outside of these guidelines. Use the settings that bring the best results for your materials.

Fabric Type	Temp (F)	Pressure	Transfer Press Time	Peel Delay (cold peel film)	Finish Press Time
Cotton	300^◦ to 320^◦	50-70 PSI Stahl’s 5-7	20 sec	60-90 sec	10-20 sec
Polyester	260^◦ to 280^◦	50-70 PSI Stahl’s 5-7	20 sec	60-90 sec	10-20 sec

If you experience the film coating itself transferring to polyester or poly blend fabrics (example photo), try increasing the temperature to 300 and the transfer press time to 30-45 seconds.

Cut out the image that you want to transfer to a garment from the film roll or sheet.
Place the garment to receive the image transfer onto the heat press.

An initial pre-press of the garment prior to the transfer press can be helpful to remove any wrinkles and slight moisture in higher humidity environments.

Place the DTF print on the garment, with the ink & glue side of the film directly against the fabric, positioned exactly where you want it transferred.
- Verify that the collar, shoulders, and any seams are draped off the side of the heat press to ensure proper pressure at the transfer location
Place a silicone sheet or kraft paper on top of the film.
Press the transfer onto the fabric using the above table for temperature, pressure, and duration.
Remove the garment from the heat press, and lay it on a clean, flat, hard surface.
When using cold peel film, delay this step for a minute or so, until the inked area of the garment has cooled down to room temperature. Carefully peel the film away from the garment at a moderate rate.
Place the shirt back on the heat press with a sheet of parchment or Kraft Paper or a white silicone sheet between the shirt and the top of the heat press, then perform a final “finish” press for the duration shown above at the same temperature and pressure as the transfer. This further cures the surface of the print and creates a smoother transition between ink & fabric.

The transfer process is now complete!

Artwork Design for DTG & DTF

All good quality prints begin with good quality artwork. The best quality shirts, perfect pretreat application, and excellent inks & printers cannot correct problems with the actual image being printed.

Image Creation Guidelines

Aesthetic qualities aside, there are a few important considerations when creating or sourcing any artwork for DTG & DTF printing.

Transparent background: Unless you want a rectangular print for creative reasons, be sure to make the background transparent. This will not only make the subject of your artwork pop visually, it will also save all the ink that would otherwise be used to print the background.
300 DPI resolution: The higher the resolution of your artwork, the better your print can look. We recommend using 300 DPI to avoid jagged edges on curves.

Size artwork to desired print size: Expanding or zooming in on artwork causes jaggy curves, so create your designs at the size you’ll be printing or larger.
PNG: Our recommended file format is PNG for storage efficiency (with lossless compression) and support for transparent backgrounds & opacity. TIF, PSD, JPG, GIF, and other formats also work with our DirectRip software, but PNG has the best combination of features, is most commonly used, and is widely supported by graphics creation & editing software.
RGB: Yes, your printer uses four-color CMYK inks, plus white for the underbase and highlights. However, the DirectRip software is optimized to convert the RGB colors commonly used for PC computer graphic work to CMYK+W when printing. So we recommend using RGB for your design.

Working with Customer-Provided Images

Customers may request that you print a design that they provide to you as a graphic file. This in itself is not a problem, but it’s important to check the parameters of their designs and let them know proactively if you have quality concerns. As mentioned above, make sure any file you accept is 300 DPI and sized appropriately for the size of print they want to have.

Downsizing is easy & quick to do in DirectRip, so oversized images are fine. But images that are much smaller than the desired print size will not result in the quality of print that you want associated with your DTG printing business.

The same goes for use of clip art or images saved from the Internet. Make sure they’re designed for larger format printing using the parameters referenced above.

Your printer can produce incredible quality prints! Don’t let your reputation for quality printing take a hit due to poor quality source graphics.

Consumable Parts & Routine Maintenance

Consumable parts are those parts that are expected to require replacement on a regular basis, as part of normal maintenance for optimal performance and reliable operation, not due to any manufacturing defect.

While consumable parts are expected to require replacement as part of normal system maintenance, you can maximize the service life of these components by staying on top of your routine maintenance schedule.

Parts that are exposed to both ink and air need to be cleaned after each day of usage, to prevent ink from drying and building up over time. Ink build-up on the capping station, wiper blade, or printhead undercarriage can result in nozzles clogging and potentially require replacement of the printhead. Diligent and thorough maintenance is the best way to minimize the need for consumable parts replacement.

Probably the most familiar examples of consumable parts are tires and air & oil filters on a car. The fact that they have to be replaced periodically does not point to any type of flaw — it’s normal and expected.

A damper for the Freejet 330-series DTG printers — a consumable part.

Some of our consumable parts are dampers, ink clips, ink tubes, o-rings, and pumps. Just like tires wear out, so do consumable parts on your printer. These types of consumable parts periodically need replacement due to normal wear.

Your warranty does cover any defects in parts or workmanship, and if a consumable part is deemed by OmniPrint staff to have been defective on a brand new printer it will be covered. We also provide a limited warranty on the printhead against spontaneous clogging, while other DTG manufacturers typically treat print heads as consumable parts. (Damage or clogging due to head strikes or lack of maintenance is not covered.)

Choosing the Right Garment

When choosing a garment for DTG printing the most important factor will be the quality of your garment. High-quality garments will produce high-quality results, while low-quality garments will produce poor results. And since OmniPrint’s DTG ink is water-based, certain fabrics interact better with the pretreatment, ink, and fabric.

We recommend experimenting with various fabrics by a variety of manufacturers to see which garments work well with your graphics. Typically, DTG printing works best on natural fabrics and natural-synthetic blends. It will take practice to find the right pretreat amount based on the fabric type, fiber content, and amount of pretreat. Here are some general guidelines to consider:

Garments with loose weaving may allow pretreatment to migrate away from the top of the fabric, resulting in spotty prints and poor washability
Cheaper than average garments should be a warning of low quality
Rayon or spandex dominant blends tend to scorch when curing the ink so should be avoided
Avoid Carded Open End and garments with too many stray fibers
Combed Ringspun 100% Cotton is the preferred garment choice
The 330TX model can print on up to 50% polyester
The 330TX PLUS model can print on 100% polyester

Once you have considered and optimized these factors you can print on:

Beach towels
Canvas tote bags
Hoodies
Crew neck t-shirts
Polos
Toddler shirts or onesies
Jeans
Hats
Etc…

Climate Control Requirements

It is important to maintain a temperature range of 60° to 80° Fahrenheit and a Relative Humidity range of 45% to 65% to avoid negatively impacting:

Print quality
Proper consistency of ink and pretreatment
Shelf life of ink, adhesive powder, and pretreatment
Service life of print head

How does the environment impact print quality?

If the humidity is too high, fabrics can absorb and retain moisture, causing ink to bleed. We recommend doing a final heat press on any garment that was previously pretreated to steam out any moisture and remove any wrinkles.

How does the environment impact ink and pretreatment?

The shelf life of our inks and pretreat material is normally one year, but temperatures exceeding 80° Fahrenheit can cause the consistency of inks and pretreatment to permanently change, whether in the equipment or still in their original containers. If this happens the nozzles of the print head or pretreat device may clog, so the material should be replaced to avoid damaging your equipment.

How does the environment impact the service life of the print head?

If the humidity is too low atomized ink can dry on the print head plate and cause clogging. Also, if temperatures exceed 80° Fahrenheit the consistency of the ink can permanently change and result in clogging print head nozzles, potentially requiring that the print head be replaced.

Clogging of the print head due to temperatures or relative humidity outside of the recommended ranges is not covered by your printer’s warranty.

Head Strike Avoidance & Recovery

One of the most potentially damaging problems that can occur with your printer is a head strike or head rub. Avoiding this will extend your printhead’s life and save you the expensive of lost time & materials, and possibly expensive repairs.

What is a head strike?

A head strike is when a printhead contacts a garment, film, or platen.

Results of a head strike

If a head strike occurs, the printhead may be damaged. If the head strike is on a pretreated garment it will likely clog nozzles and may permanently damage the printhead. At the very least, a head strike will smear ink on your print so result in scrapped materials.

How to avoid head strikes

Properly positioning the platen, mounting the garment, setting the platen height appropriately (so that the print head has sufficient clearance), and keep the film properly aligned (in DTF printing) will ensure that you avoid experiencing a head strike.

What to do if you get a head strike

Immediately lower the platen (on DTG printers).
Abort the print job.
Prime all ink lines for a full pump cycle (on Freejets) or Load Ink for 15 seconds.
- Monitor the waste ink bottle and interrupt priming to empty it, as needed.
Run two head cleans
Print a nozzle check

If the nozzle check is good, continue printing to keep ink flowing through the nozzles, then wet cap in Super Nozzle Cleaner overnight when finished printing.

If a good nozzle check cannot be achieved by following the above steps, contact tech support to see if permanent damage can be avoided.