How to Flip the Substrate and Align Front-Back Printing — UV Printer Products (Part 2) ARTJET 2026

1. The printing method for the image shown below is explained as follows.

• The substrate in the photo below is 1.5t transparent acrylic.
• To precisely align front and back images after flipping the substrate, the material must be transparent.
• On the front side of the acrylic, White was printed across the entire surface, while Color was used to print only the alphabet letters and braille dots flat.
• On the back side of the acrylic, the substrate was flipped and positioned, then Varnish was printed aligned to the Color braille dot positions.
• The Varnish was layered to create a raised dome effect, completing the braille.
• The reason the Varnish appears black is that the black Color printed on the back of the acrylic shows through — making the Varnish look black.
• If the braille dots were printed in red, blue, or another color, that color would show through instead.

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  How to Flip the Substrate and Align Front-Back Printing

2. For Non-Transparent (Opaque) Substrates

• ‘A square substrate has all edges at exactly 90 degrees’ — this is a common assumption, but when you actually measure the angles, they are never perfectly 90°.
• Since the substrate is not a perfect square or rectangle, aligning one side as a reference means the opposite end will be slightly off from the intended position.
• If you flip the substrate upside down and print in this state, the starting point may align, but the endpoint will not match.
• For non-transparent substrates like standard Forex (foam board), to precisely align front and back printing:
• The substrate itself must have crop marks cut into it, and the UV printer flatbed must also have corresponding registration marks — so that position values can be matched using those references.

Here is a brief overview of the entire process, followed by detailed step-by-step instructions.

• RIP the front-side image through Flexi RIP (Mirror option and left-right direction settings are critical)
• Print the RIPped image on transparent film first to establish the position reference
• Place the acrylic on top of the transparent film and print the same image to complete the front side
• Explanation of whether to flip the substrate left-right or top-bottom after printing
• RIP the back-side image through Flexi RIP (Mirror option and left-right direction settings are critical)
• Print the back-side image

1. Flexi RIP Settings for the Front-Side Image

1_1. Flexi RIP First Screen

• Our printer automatically mirrors the image when printing in Reverse mode.
• Because of this, you do not need to select the ‘Mirror’ option in the RIP.
• In Flexi RIP, do not select the image Mirror option — leave it as “F” (this is the Mirror option toggle — clicking it again flips the F horizontally, enabling Mirror)
• In the image Rotation option, set the head direction to face “⇐”

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  How to Flip the Substrate and Align Front-Back Printing

1_2. RIP Fourth Option Screen

• Click the 4th icon at the top of the screen shown below to open this window.
• In the Spot_1 White option, select “Substrate” — this will automatically print White across the entire image file.
• In the Spot_2 Varnish option, since only White and Color need to be printed, select “None.”

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  How to Flip the Substrate and Align Front-Back Printing

2. Print on Transparent Film to Establish Position, Then Print the Front-Side Image

2_1. Printer Program Option Settings

• Since the acrylic is transparent, go to Menu → Spot Color options and select [Reverse Print] for back-side printing.
• White density is set to 50% (6 channels × 50% = 300% White density).

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  How to Flip the Substrate and Align Front-Back Printing

• The print mode doesn’t matter too much, but I used bi-directional output in Quality mode.

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  How to Flip the Substrate and Align Front-Back Printing

2_2. Print on Transparent Film to Establish Position References

• After printing on the front of the acrylic, to flip the substrate and place it in the exact position, the printer flatbed itself must have position markings — even after the substrate is removed.
• This is achieved using a transparent film.
• Place the transparent film on the flatbed.
• Vacuum must remain active at all times to prevent the position from shifting.
• Tape the top of the transparent film to keep it in place.
• The photo below shows the tape applied at the print start point, with the front-side Reverse Print completed.

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  How to Flip the Substrate and Align Front-Back Printing
• Once printing on the transparent film is complete:
• Cut out the center as shown in the photo below, leaving only the White border around the edges.
• If the center is not cut out, vacuum suction will not reach the acrylic substrate — and the LED heat during printing may cause the substrate to warp and hit the head.
• Cut the center to allow vacuum to act on the acrylic, and leave the White border as the position reference.

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  How to Flip the Substrate and Align Front-Back Printing

3. Print the Front-Side Image on the Acrylic

• Place the transparent acrylic on the flatbed.
• Tape the edge areas where vacuum suction is blocked by the transparent film.

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  How to Flip the Substrate and Align Front-Back Printing

• After changing only the print height to match the acrylic thickness, print the same image from the transparent film onto the acrylic.

• The photo below shows the first image mid-print in Reverse mode. If you look closely, black dots are printed in Color, followed by White being printed.

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  How to Flip the Substrate and Align Front-Back Printing

4. Which Direction to Flip the Substrate

• Once printing is complete, flip the substrate left-to-right (not top-to-bottom), as shown by the arrows in the photo below.
• The head direction in the RIP settings, the Mirror option in the program, and the substrate flip direction must all follow the manual exactly — only then will the front and back image positions align precisely.
• You must follow every step from the beginning to the end exactly as described to achieve accurate front-back image alignment.

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  How to Flip the Substrate and Align Front-Back Printing
• After flipping the substrate, position it precisely against the White border remaining on the transparent film.

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  How to Flip the Substrate and Align Front-Back Printing
• Just like the first image print, tape the edge areas where vacuum suction is blocked.

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  How to Flip the Substrate and Align Front-Back Printing

5. RIP the Back-Side Image Through Flexi RIP (Mirror Option and Direction Settings Are Critical)

• This is the same option window used for the first image.
• For the second image, select Mirror so the F is flipped horizontally, as shown in the photo below.
• Change the head direction to the opposite of the first image: “⇒”

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  How to Flip the Substrate and Align Front-Back Printing

6. Print the Back-Side Image

• In the printer program, go to Menu → Spot Color options and use the same “Reverse” setting as the first print.
• If the first image was printed in Reverse Print mode, the second image must also be printed in Reverse Print mode.
• The second image requires Varnish to create raised braille dots — meaning the Varnish must be layered thick. In other words, layered printing is needed.
• The method for creating braille through layered printing was explained in the previous article.
• Follow the settings described in the link below, and the Varnish will print precisely aligned to the black circle positions printed on the back side.
• Braille Printing
• The content explained today is also available as a video via the link below.
• How to Flip the Substrate and Align Front-Back Printing (Video)