This article provides a step-by-step guide for users of 240 Tech / OvalJet printers in DTG (Direct-to-Garment) workflows with CalderaRIP. It covers the necessary steps for calibrating and profiling colors in this type of production.
Prerequisites
- OvalJet-DTG and OvalJet 3 drivers installed.
- DTG Workflow calpatch installed.
You may be interested in reading: 240 Tech / OvalJet - DTG printing workflow
Linearization and profiling with EasyMedia
The two Ovaljet drivers are synchronized together, but some setup needs to be done manually when building the profile.
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To develop and manage a color profile, a spectrophotometer is required. The recommended spectrophotometer is the Caldera's TotalColor QB. This device features a large aperture and fast scanning speeds. It allows for multiple readings per patch to help with the inherent defects when printing directly to a garment.
After launching the EasyMedia module, select the printer icon to begin the calibration process:
Select the Ovaljet-DTG server. The Ovaljet-DTG server is where the profile will be created:
As the profile is created, the necessary components are moved to the second driver. If prompted, the CalderaRIP password is “caldera”.
In this step, the media needs to be created. Typically, media is the color and type of material:
The white max. % needs to be set › depending on the garment type, desired hand-feel, and washability:
The minimum and maximum levels can be set for the white channel. This is helpful for some garment types that benefit from always having a white under base. Maximum white needs to be confirmed before building a complete profile to get the optimum amount of ink without too much, which causes bleeding.
The minimum white must be set to 0 during the linearization process. Without this value set to 0, it will not allow the white channel to turn off effectively. Once the linearization has completed, this value should be changed before profiling.
Next, Mode and Resolution need to be defined. Ovaljet has modes for white, black, and colored garments:
What color mode should be selected?
Colored T-shirt mode profiles produced on a Grey garment are the most versatile. This color mode will reproduce colors across multiple garment colors successfully.
CMYKRG mode should be used for white garments since you will usually not require a white under base. This makes these profiles unsuitable to run on colored areas of the fabric.
Black T-shirt mode profiles will use only garment colour for black, using no black ink. Running this mode on white or color shirts would produce incorrect colors. It is also valid to use Colored T-shirt mode on black garments if black ink is desired (e.g., when using the White-min option to improve wash fastness).
Creating a profile for every garment color would take a significant amount of time, but since we are using the garment color in the profile creation, you would see ink savings and improved color accuracy from this process.
If White-min is used to improve wash fastness, Colored T-shirt mode must be selected; otherwise results will be incorrect.
What resolution should be selected?
Currently, the Ovaljet is utilizing the resolution of 800x1800 to achieve its output quality. This resolution is only for the color and white separation.
In this stage, the output color mode and Pretreat must be configured per the manufacturer's specifications:
Once the Ovaljet-DTG driver has been initially configured, the Ovaljet3 can be configured with the matching profile.
The output color settings can be for multiple resolutions. However, the output for the pre-treat mode should always have the resolution set to Pretreat:
Add a new mode to the profile. The mode will be Pretreat, and the resolution is Pretreat. Once the Pretreat mode has been created, a linearization can be created:
The curve can be manually adjusted to achieve the desired results.
To manipulate the pretreat curve, the number of control points can be changed to allow more flexibility.
The icons on the bottom left of the chart will also allow for curve adjustments.
Once created, return to the status tab to save the project:
When starting a new project, all of the project files will show none since there is no data in the project:
Return to the Ovaljet-DTG driver once the Ovaljet3 has been configured.
The color management profile is built on the Ovaljet-DTG driver. The linearization curve will be moved to the Ovaljet3 driver automatically.
When starting a new project, all of the project files will show none since there is no data in the project:
Navigating EasyMedia
Since CalderaRIP’s EasyMedia module is a wizard-based during the profiling process, after each step, you will select the next button at the bottom of the wizard. You can also, at any time, return to the status tab by selecting it to save your project in its current state. If you reopen a project, you can go to the current step by selecting the corresponding tab as well.
Since this is a new profile, we will create new linearization curves using the wizard option:
The spectrophotometer that will be used for profile creation needs to be selected along with the target:
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The target selection is critical. When working with textiles, we recommend using the 2.5% step or the exponential target. These targets help to achieve a larger range, and they help average the reading from a single pass print. Also, be sure to use a target with large swatches supporting an 8mm aperture.
In the printer settings, the percentage of pretreat should be set. Pretreat should generally be 100%, as the previously defined curve will adjust it as required. In T-shirt mode, white is automatic and can be disabled:
The spectrophotometer that will be used for profile creation needs to be selected along with the target:
Warning
The total amount of ink and pretreat will affect the washability, quality, and hand-feel. Ensure White min is 0 for linearization.
Selecting the print button will send the print-ready files, including white and pre-treat, to the output folder:
Printing the perfect target for measurement
The target needs to be printed on one shirt without any defects. This is a critical step. Any imperfections on the shirt or printed on the target can cause a misread, resulting in a poor linearization curve. Check for missing nozzles and print inconsistencies, and correct and reprint if necessary.
You also want to make sure you do not distort the garment when removing it from the dryer. Distorting the printed piece will make measuring more difficult.
Once the device is configured, you will select the start button to begin the measurement process:
Device Setup
The M0 measuring condition tends to be best for DTG. It helps to manage how the optical brightening agents are measured.
The speed setting will be set to Contactless. This ensures the head of the measuring device will not rub on the print, causing defects.
Multiple patch readings will always be best for textiles. These readings help to average the data to account for the inherent imperfections in a garment. If you are using another device, such as an i1, you can manually read in the target twice and average the readings together.
The aperture is 8mm on the TotalColor. For any other spectrophotometer, you will want to use the largest available. The larger aperture helps to get a broader snapshot of the swatch itself to reduce imperfections in the linearization curve.
When building a profile in color shirt mode, it will appear to have two black channels. In actuality, the first Black channel is shirt color:
Inspect for dips and inconsistencies in the curve. This noise can cause issues in the transitions. Noise can be manually smoothed with the correction curve.
Curves can be smoothed by using control points on the correction curve:
Adjusting the total number of control points allows for easier manipulation. When rationalizing the control points, the goal is to remove the dips and spikes from the curve.
Configure the Shirt Color Channel
To print pure shirt color without any white, such as transparent areas, CalderaRIP must be able to achieve 100% shirt color. So, it is very important in this step to set the Pmax for the first Black channel to 100%. If this value is not set to 100%, you can have a halo effect around lighter areas of the print.
Once the Pmax has been set, continue to the correction curve.
For this step, data points should be displayed in Numbers. When using a shirt color, the readings at 90%, 95%, and 100% must be at least 98%. If the readings are below 98%, you can manually adjust them to above 98%. If this step is ignored, a white halo effect can occur. To make this adjustment, set the chart to 20 control points.
When the Ink Limit target is generated, ink mixes are made. However, when looking at the ink limit, part of the target will use less ink. The loss in saturation is due to the target being generated with the shirt color. So, if parts of the target are seen with less density, ignore those when choosing the ink limit.
When referencing the target, you can lean one of two ways.
Higher ink limit will be slightly saturated, allowing for a little bleed from square to square. The higher limit will allow for a somewhat larger gamut that uses more ink. Setting the ink limit slightly lower will have minimal bleed, slightly smaller gamut, and lower average ink use per print.
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If the swatches look below acceptable standards, the max white levels may need to be adjusted.
Once the ink limit has been entered, return to the status tab and save the project:
Once you save the project, return to the menu and select the OvalJet3 driver.
Inside the Ovaljet3 driver, you will see that the media has been created. The color and white linearization curves have also been moved over.
You can confirm the linearization has been moved because the file name will show in the Status tab:
Confirm both the white and color modes have a linearization file attached.
If the linearization file is not visible, confirm that you saved the project. If the linearization still isn’t moved, the dtgworkflow patch might need to be reinstalled.
When the shirt color curve is moved into the Ovaljet3 driver, it is no longer inverted in shape.
The shirt color curve was converted to a white curve.
The zero points of the curve must be 0,0. If the white curve does not start at 0, a halo effect will occur. This is due to white being placed under all colors and being used all the time.
If the min white feature is turned on during linearization, this curve will end flat on the bottom. During the profiling process, it is essential to leave the minimum white setting "off".
Once confirmed, return to the working profile in the Ovaljet-DTG driver.
Once back in the Ovaljet-DTG driver, you will view straight lines if you check the linearization curves.
This is because the curves generated from the readings have been moved to the Ovaljet3 driver.
Now that the linearization and ink limits have been completed and confirmed, it is time to build the profile using an ICC target. From the linearization tab, you can select the Profiling tab to begin the process.
The recommended target for profiling is the ECI 2002 for 6/8mm aperture, 4 pages, 1mm gap. This target has enough swatches to get favorable results within the ICC. Since the Ovaljet utilizes shirt color and white, it is crucial to have plenty of swatches. The increased number of swatches will add detail to the profile that helps to improve gradients.
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If minimum white will be used, this is now the point in the profiling process to enable.
To enable this setting, return to the profile mode and edit the parameters and define your desired value.
This must be done before the profiling swatches are printed. If the setting is not made before submitting to print, the file will not have the minimum white setting enabled.
The large profile size must be selected to get the most data points.
D65 is also recommended for textile DTG profiles.
Other settings are great as defaults. However, the smoothness/accuracy setting can be changed to help achieve smoother gradients or higher color accuracy.
Separation method setting Max Black.
Disable intelligent black.
These settings will allow for the best white and black generation within the profile for DTG.
Once these settings are made and the profile is built, a warning might be displayed. The notice states that the white point is not the whitest. In this case, use the regular white point, not the one it found.
Once the profile is built, continue back to the status tab and save the project.
Once the color, white, and pretreat modes have been configured, the profile is complete.
It is recommended to use a testing target to review the profile.
After the profile has passed the quality assessment, a media calpatch should be exported and archived. A calpatch must be exported from both drivers to be reused later.