Sunlight brings out the colors!


  • Large-format inkjet printing
solar print


This is a printing process that uses ink that develops full color when exposed to sunlight.The colors are repeatedly generated and removed depending on the presence or absence of sunlight. Since it is possible to reproduce full color with natural sunlight, it is now being used in a wider range of applications, from conventional single-color UV checkers to advertising, sales promotion materials, DMs, and other planning and toy product tricks that use solar energy to promote products and lead people outdoors.

Types of triggers to change the design of SOLAR PRINT


UV handy light

UV pen light

Technology Overview

Photochromic is a printing technology that is invisible in normal light, but produces full color when exposed to sunlight. Photochromics are excited and colored by natural sunlight, and gradually disappear when the sunlight is blocked.

About raw materials

The raw material of solar ink is photochromic dye (powder), which is the raw material of ink. Depending on the compound, the ink can be colored in the four primary colors of cyan, magenta, yellow, and black (CMYK). Excitation light around 365nm, which is the near ultraviolet light contained in sunlight, produces strong color.

Excitation light: General term for light that causes excitation in materials such as phosphors.

About overlapping colors

Vertical lines are printed with normal ink and horizontal lines are printed with solar ink.

photochromic printing

Indoor light

photochromic printing


When the total amount of ink reaches 200% or more by printing normal ink and solar ink data at the same time, blurring will occur.

Sunlight by season and time

photochromic printing

Time of day to enjoy the color of solar prints

SOLAR PRINT, which can produce full-color prints using ultraviolet rays from sunlight, has the best time and period for reproducing the best color depending on the strength of the daily ultraviolet rays and the period of sunlight. The circle in the graph is the recommended time.

Changes in UV radiation levels over the course of a day

photochromic printing
  • ・・・Recommended time zone. The best full color reproduction can be enjoyed. The degree of coloration varies depending on the amount of ultraviolet light.
  • ・・・Since the UV light is weakened, the color will be 10-30% lighter than the best full color 100%.

For UV radiation levels outside of summer and winter, please refer to the monthly graphs.

Change in UV radiation by month

photochromic printing

Changes in UV radiation levels due to weather

This is the amount of UV radiation when the UV radiation in clear weather is 100%.

photochromic printing
good weather
Amount of ultraviolet rays 100%
photochromic printing
Amount of ultraviolet rays 98%~90%
photochromic printing
slightly cloudy
Amount of ultraviolet rays About 80%
photochromic printing
Amount of ultraviolet rays About 60%
photochromic printing
Amount of ultraviolet rays About 30%

About weather resistance

Irradiation verification under artificial sun, assuming 12:00 noon in midsummer!

Measurement conditions Artificial sun, irradiation distance 84cm
Measurement object Solvent inkjet printing,SOLAR PRINT, synthetic paper
Verification environment Irradiated by artificial sun assuming mid-summer daytime.
photochromic printing

Figure 1: (5-second irradiation)

photochromic printing

Figure 2: (55-second shutdown)

photochromic printing

Figure 3 (55-second shutdown)

Irradiated approximately 5,760 times. The color is reduced by half.

The results of a test in which UV light was irradiated for 5 seconds (Figure 1), the color was generated, and then the UV light was blocked for 55 seconds to eliminate the color (Figure 2). As a result, the color halving was observed after about 5,760 times of irradiation. (Fig. 3) In the verification of continuous irradiation, the color halving was observed after about 4 to 5 hours of irradiation when the UV light was blocked on half the surface.

Please try to avoid continuous exposure to direct sunlight, which reduces the color of solar prints by half, and leave the prints unattended.

photochromic printing

About UV-cut glass

When checking the solar print near a window, the color effect of the SOLAR PRINT may be weaker than it should be because the transmission of ultraviolet rays is weakened indoors.

Ink sales

Solar ink (for offset printing)
This is an offset ink for "SOLAR PRINT" that reacts to the ultraviolet rays of sunlight and changes the design.

Ink sales

Solar ink (for screen printing)
This is a screen ink for "SOLAR PRINT" that reacts to the ultraviolet rays of sunlight and changes the design.

Inkjet system

Sales of inkjet systems capable of SOLAR PRINT
SOLAR PRINT System for MIMAKI JV33 and MIMAKI JV3, complete with RIP software, ink and other necessary items. The system enables output and print order service under the customer's large format printer environment. Ink refill is required.