November 6, 2024 Longchang Chemical

Spot colour ink: it is a pre-mixed specific colour ink, such as fluorescent yellow, pearl blue, metallic gold and silver ink, etc. It does not rely on CMYK four-colour overprinting, and overprinting implies the exact colour.

Spot colour ink blending
1 Ink blending basis
1、Basic colour ink

Basic colour ink is divided into three categories according to different mixing methods: primary colour ink, standard inter-colour ink and standard compound colour ink.

Primary colour ink: it refers to the three primary colours ink which can not be mixed by other colours, such as yellow, magenta, cyan ink. Three primary colours of ink from the theory, according to different ratios and ways of mixing, can be deployed in a variety of different colours, but in practice, no matter how to mix and match can not be equipped with pure ink colour. Therefore, in colour printing, most of the use of yellow, magenta, cyan, black four-colour ink to overlay ink.

In addition, different countries and manufacturers of four-color ink production standards are not the same, such as China’s offset printing glossy fast-drying four-color ink colour designated as medium yellow, magenta, sky blue and black.

Standard Intercolour Ink: refers to the colour ink formed by mixing any two primary colours in equal quantities.

Standard Compound Colour Ink: refers to the colour ink formed by mixing any two intermediate colours in equal quantities or three primary colours in different proportions.

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2、 Dark Spot-colour Ink Blending

Using one or several kinds of primary colour ink without adding any diluent for colour mixing is collectively called dark spot-colour ink blending. According to the principle of subtractive colour method, when mixing dark ink, the number of original colour ink should be used as little as possible. Otherwise, it will reduce the brightness of the ink and colour vividness. However, some products have special requirements for ink colour, such as dark brown ink with red ink, yellow ink plus a small amount of black ink blending. In addition, with different proportions of the three primary colours mixed bronze, red purple, dare olive green and other shades of compound colour, it must be complementary theory to correct its off-colour, such as the green phase is too heavy, can add a small amount of red ink to correct; the red phase is too heavy, can add a small amount of blue ink to correct; violet flavour is too heavy, can add a small amount of yellow ink to correct; if you want to deepen the concentration of black ink, can be added a small amount of crimson, shooting blue to adjust. Just as in the production of offset black ink, with shooting blue, sunlight-resistant red, phthalocyanine blue and other pigments to adjust the same principle of the black ink hue. Spotlight blue is often used in spot-colour ink, it can eliminate the original brown background of black ink, so that the black ink is deeper and denser.
3、 Blending of light spot-colour ink

Where the need to add the punch or white ink ink colour blending collectively referred to as light-coloured ink blending. Blending light spot-colour ink can not be used in the original colour ink to add the method of lightening agent, because the original colour ink in the talk agent in the colour development ability is strong, and the original colour ink colouring power is not the same, easy to cause the colour phase is not allowed and waste of the original ink. The correct blending method is to gradually add the original colour ink in the lightening agent, and then expand the proportion to blend the required amount of ink after the colour phase reaches the requirement.
Light-coloured ink can be divided into three kinds:

(1) The light-coloured ink is mainly based on the lightening agent: it has a certain degree of transparency and is suitable for multi-colour overprinting of the ink.

2] white ink-based matte type ink: it has a strong covering power, ink colour is more vivid. Generally, the light-coloured ink for synthetic paper is made with white ink.

3] Light-coloured ink mixed with lightening agent and white ink.

Mixing method of spot-colour ink
1、Proportion method

Ink colour blending, the first step is to carefully observe and analyze the ink sample or print sample. Ink samples, can be Dowling paper scraping sample, you can also use the printing suitability of the instrument to print out the print sample, generally four sections of the roller ink amount of 0.1 m, two sections of the roller ink amount of 0.15 ml. First of all, we need to observe, analyse the print sample may be made up of which colours of ink, available with a graduated copper ink pipe, according to the proportion of the rough adjustment. Look at the rough adjustment of the ink sample (scraper) and the standard sample is not close, and record the ink ratio and ink volume. If close, the proportion of the number converted into a percentage, and then use the analytical balance fine-tuning; if not close, should change the name of the proportion of ink and ink, continue to mix.
2、Decrease method

Has determined the standard sample (customer provided standard colour samples or not close to the standard sample of ink samples) by which the colour of the ink composition, find out the ink contained in the name of 10g or 5g on a glass plate with sulfuric acid paper, any ink used to transfer, when the ink is close to the standard sample, the ink can be used to scrape a little ink samples, observation of the face colour, the bottom of the colour, scraping ink used to retract the film. If close to the standard sample, weighing the remaining amount of ink can be converted to the percentage content of the spot-colour ink. Then use the balance fine-tuning, if the near-standard sample, continue to blend.
3、PANTONE colour matching method

PANNTONE Formula Guide’ 2000 version of the Pantome colour guide contains 1114 kinds of Pantome spot-color, is the world’s common colour guide, it provides a standard for each colour, there are numbered and adjusted to the ink ratio, the use of fan-shaped binding, selecting the colour is fast and convenient. Pantome spot-colour inks, we should carefully observe and analyse the printing samples, compare them with the colour samples of Pantome’s colour matching guide to find out the close colour samples, and if they are very close to each other, we should write down the colour serial number and compare the printing samples of TCT-type inks with the colour matching guide correspondingly, and then analyse the printing samples of the two colour matching guides to see whether they are consistent or not; and find out which one of the ratios of inks is caused by the error if there is such an error. If there is an error, find out which proportion of ink is responsible for the error. After analysing the sample, you can adjust the proportion of ink used for the sample. This will make the mixing work relatively easy.
Spot-colour ink blending points
The operation process of mixing spot-colour ink. Blending ink should pay attention to the following points.

(1) taking into account the characteristics of post-press processing: the choice of ink, take into account the situation of post-press processing, for example: prints need to be varnished, the choice of general ink can be, if you choose to friction good ink, not only the cost is high, the face of the Ming influence on the effect of varnish.

(2) the same kind of mixing: ink mixing should try to master the same type of mixing principles, such as the mixing of inter-colour and compound colour, if there is no offset glossy quick-drying ink, you can use offset resin-based ink instead, but should pay attention to the proportion of mixing, if the offset resin ink is too much, on the offset glossy quick-drying ink will have an impact on the characteristics of the ink, and fail to improve the quality of the prints of the purpose. Ink colour knowledge tells us that the more varieties of ink mixing, the darker the colour. Therefore, can use the original colour ink, never use the inter-colour ink; can use the inter-colour ink never use the compound colour ink.

(3) determine the basic ink: the colour of the printed sample to be more than two ink blending, to determine which colour as the basic ink, and gradually add other ink; such as light-colored ink as the basic ink, and gradually add dark-colored ink. So that the amount of ink is not too much.

(4) the density of the sample consistent: according to the printing of the colour mixing, the ink samples in the printing of the film to adjust the amount of ink, so that it is consistent with the density of the sample.

(5) attention to records and calculations: especially when adjusting spot-colour ink according to the proportion method, we should always record the amount of ink added, the remaining amount of ink, etc., which is conducive to the calculation of the final ratio.

(6) Adjustment of ink: in the deployment of spot-colour ink, in addition to colour matching, sometimes need to add a certain amount of additives to change the ink to meet customer demand.

(7) pay attention to the printing method and characteristics: when mixing ink colour, should consider the printing method and characteristics, clear matching oil silmer is used for what kind of printing method, such as letterpress or lithography, printing field or printing screen, etc.. Because different printing methods to form the thickness of the ink layer is different, the colour is also different. For example: for printing mesh-based ink, can focus on the bottom of the colour in the colour; if the field-based, colour can focus on the face of the same; if both sometimes, that the bottom and face colour should be taken into account.

(8) consistent paper: the deployment of spot-colour ink used in paper and printing paper to maintain consistency, to avoid colour errors caused by different paper.

(9) the same time to print samples: to provide customers with ink samples as samples blending spot-colour, samples and samples need to be printed at the same time to compare, so as to accurately determine the colour differences between them.

(10) weighing accuracy: blending colour to find out the initial ratio, must be fine-tuned with a balance, so as to ensure that the small adjustment samples (5g), enlargement of the sample (100 to 2000g), the colour of the production sample is consistent. And pay attention to mix evenly.

Spot-color ink generally requires high accuracy of the colour, it is qualified or not, not based on the approval of the blending staff as a benchmark, but to enlarge the sample in the printing plant after printing into the print, the customer’s satisfaction as a benchmark, or after the measurement of colour measuring instruments to confirm.

Application of Spot Colour Ink
What kind of products will be printed with spot colour inks?

Packaging products or book covers are often composed of uniform blocks of different colours or regular gradient blocks of colours and text, which can be overprinted with four primary colours, or spot-colour inks can be deployed, and then only a certain spot-colour ink can be printed in the same colour block. In the comprehensive consideration of improving the quality of printing and save the number of overprints, sometimes the choice of spot-colour printing.
Spot-colour printing block and four-colour overprinting of the block of colour visual effect of what is the difference?

Spot-color printing ink is blended in accordance with the colour subtractive colour mixing principle to obtain the colour, its colour brightness is low, high saturation: ink uniform spot-color block is usually used in the field printing, and to appropriately increase the amount of ink, when the layout of the ink layer thickness is large, the ink layer thickness changes in the colour changes in the degree of sensitivity will be reduced, so it’s easier to get ink uniformity, thick printing effect.

The use of four-colour printing work set out of the colour block, due to the composition of the colour block of the various colours are mostly composed of a certain proportion of dots, printing dots, the ink layer thickness must be strictly controlled, easy to change due to changes in the ink layer thickness and printing process conditions caused by changes in the colour intensity changes. Changes in the degree of expansion of the dot. This leads to colour changes. And because of the composition of the block of any one colour change will lead to the colour of the block of colour change, resulting in the appearance of uneven ink colour opportunities will be doubled, so the use of four-colour printing process overprinting out of the block of colour, it is not easy to obtain the effect of uniformity of ink colour. If you can not use multi-colour machine to overprint the colour of the colour block at a time. Also prone to colour bias due to the colour of semi-finished products is not easy to control. In addition, four-colour printing is obtained from the dots of the subtractive colour absorption and additive colour mixing of the integrated effect, the colour block brightness is higher, lower saturation. For light-coloured blocks of colour, using four-colour printing process, due to the low coverage of the ink on paper, the ink is flat and lack of solid feeling. Due to the angle of the dots, the presence of patterns is also inevitable.

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From the perspective of improving product quality, what kind of products are suitable for spot colour printing?
In the printing of large areas of light uniform colour block, usually used in the original ink to add: medium light agent to mix spot-colour ink, and then field printing, so that the ink layer is thicker, easier to get uniform colour, thick effect. If the four-colour printing process, it is necessary to use a low number of flat screen dots. However, the low number of flat screen dots in the plate is prone to tiny grains of sand or pumping a little bad caused by individual parts of the dot smaller, resulting in uneven ink: printing and easy because of the layout of the water supply is too much. Paper dust in the printing plate and blanket accumulation, low paper smoothness and other reasons resulting in small dots of poor ink transfer. Thus, there is a lighter ink colour and uneven ink colour.

For dark large-area colour block, using four-color printing process, may need to be superimposed by several colours of the high salty number of dots, the ink layer is too thick and easy to appear on the back side of the rubbing; and the use of spot-colour printing process, only one colour, not easy to appear on the back side of the rubbing. Four-color printing process, some parts of the graphic may be synthesized by a few colours; and the use of spot-colour printing process, the corresponding parts of only one colour, to avoid the possibility of overprinting errors.
From the point of view of economic efficiency, what kind of products are suitable for spot-colour printing?

From the point of view of economic efficiency, mainly depends on the use of spot-colour printing process can save the number of overprints. Because reducing the number of overprints can save printing costs, but also can save the cost of pre-press production.

How accurately do inks mix colours?

Inks are commonly used in a variety of industries such as packaging printing, books and magazines, and architectural decoration. During the printing process, ensuring that the colour of each printed product is consistent is a major challenge for printing companies. If the colour of the printed product is not consistent, it will be returned or exchanged by the customer or refuse to cooperate. Therefore, in the printing industry, ink colour mixing is crucial. How to adjust the colour to meet customer requirements, manufacturers need to grasp the details of the colour mixing process.

Artificial traditional colour matching
1、After getting the samples, watch the colour samples first, study the approximate proportion of ink in the samples, or compare the colour samples with the colour card, find the colour closest to the colour samples on the colour card, and then mix the colour according to the formula on the colour card.

2、Because of the complexity of the colour change, the colour difference of the initial formula obtained by manual experience will be very big. Naked eye can see the colour deviation, but can not accurately calculate the weight of ink to be added. Can only add ink while mixing and stirring, while using hand pressure or colour spreading machine to spread the colour. As few as 3 to 5 times, more than a dozen times to add ink, ink more and more, time-consuming and laborious, and even failed to match the qualified spot-colour. The colour difference of the last spot colour is still not controlled accurately by the computer, and there is no way to know whether there is a different spectrum of the same colour.

 

For example, yellow ink, magenta, cyan three colours ink for the ink of the three primary colours, in principle, through different ratios of deployment, you can get a different hue colour to meet the needs of printing operations. Three primary colours of ink blending, according to the principle of colour subtractive colour method, with the following rules:

① when the two primary colours of ink mixing, if the mixing ratio is equal, you can get the standard inter-colour; if the mixing ratio is not equal, you get a variety of different hues of the inter-colour, the hue is biased towards the proportion of the larger party.

② When the two primary colours of ink mixed in equal quantities of colour, add white ink, the hue becomes bright; add black ink becomes dark.

③ When the three primary colours of ink are mixed, if the mixing ratio is equal, then you can get nearly black; if the mixing ratio is not equal, then you will get a variety of different hues of inter-colour or compound colour, the hue is biased towards a larger proportion of the party.

④When the three primary colour inks are mixed in equal quantities, different proportions of white ink are added, and light grey ink of different gradations can be obtained.

The above is the introduction of artificial traditional colour matching, it can be seen that the artificial traditional colour matching requires a high degree of professionalism of the colour matching personnel, and it is easy to make mistakes in the process of ink colour mixing. In the 21st century high-tech era, there have been instruments born for colour matching, greatly improving the efficiency of the printing industry.

How to accurately mix the colour of ink
AISI ColourMatch customised solutions can bring the following advantages to ink professionals:

1) Optimise colour matching under expected viewing conditions

2) Improve raw material management and better meet supplier demands by reducing ink inventories by up to 50 per cent through the use of more quantities and fewer types of materials

(3) Reduce waste ink stocks by up to 90% by using existing ink databases to save time and make best use of existing inks

4) Reduce ink (dyes/pigments/concentrates etc.) spend by 20 per cent

5) Reduce colour mismatch production waste by 50% and improve first time colour matching success rates

6) Directly reduce waste ink inventory by 25-30%, reducing the environmental impact

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