Support – Polychromal products

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Frequently asked questions

Digital printing

Black lettering bleeds into coloured backgrounds. Why is this?

Coloured lettering bleeds into coloured backgrounds. Why is this?

Lettering, lines and images on blank backgrounds dry inwards from edges and do not penetrate into the material's pores properly. Why is this?

Add a 0.5 mm border around lettering and lines using 1% K (black). We actually recommend doing this all the time to prevent numerous problems that may occur when drying.
Drying air pressure too high. Reduce air pressure.
Gamma value too high. Reduce RIP gamma value.
Ambient temperature too high. This should be between 18 and 24 °C.

Light colours disappear or become less distinct after sealing. Why is this?

Image is smudged. Why is this?

Area of contact between two colours is not sharp, but blurred (colours overlap). Why is this?

Dithering is visible in print. Why is this?

Full-colour images are blurred. Why is this?

There are patches, drips and dirt on right-hand edge of plate. Why is this?

What should I do if one or more nozzles are blocked?

Silkscreen printing

Can I dry plates immediately after printing?

Can I photo print into DuraSeal plates, e.g. if I have a job for just one plate?

What sort of screen is best for printing?

When printing a whole surface, the colour is sometimes pale. Why is this?

Photographic

Printing ink isn't penetrating into the plate, small aluminium-coloured patches remain visible. Why is this?

This may have something to do with limescale. Where limescale droplets have dried, ink cannot penetrate surface pores. If this occurs, rinse the plate off in tap water and then re-dry the plate. To minimize limescale droplet formation dab excess water off using absorbent paper, e.g. unprinted newspaper, and then heat with a hairdryer or in a kiln at a temperature below 40 °C.

When I try to re-emulsify a plate, the CopyPhot coating won't bond. Why is this?

This is a degreasing problem. After stripping the exposed emulsion, the plate should be sprayed down with soapy water (2 × drops in 500 cc of water), e.g. using a plant spray. Allow this to take effect for ten seconds and then rinse thoroughly. Ensure that no soap residue is left behind. Wipe dry using paper towels and then dry off using a hairdryer or in a kiln at a temperature below

How do I print a black plate with red lettering or images?

Using colour-separation films, i.e. two films for the example above. A negative (black) film is required for the black background in which the lettering/image is cut out (transparent). To colour the lettering red, a positive (transparent) film is needed where the image/lettering is black. Use four registration marks on both films' slug areas for alignment purposes.

Printing Sequence;

Expose negative film onto CopyPhot plate, develop, dry, ink (black) and strip. After stripping, wipe plate dry using paper tissues and then dry off using warm air (hairdryer).

Next, coat the stripped plate using Copylon photo-emulsion and a coating bar or a Foduktor (roller coater). Please find more information in our user instructions. After applying this emulsion, dry plate using warm air (hairdryer).
The transparent film for the red lettering/image can now be positioned using the reference marks printed with Colour 1. Expose, develop, dry, ink (red) and strip. After stripping, you have a black plate with red lettering/images. The process is complete once sealed.

I can't seem to rinse the plate once it's been exposed. Why is this?

When rinsing the CopyPhot plate, the emulsion begins to run. Why is this?

sealen

The colour bleeds out while sealing. Why is this?

The pH value in the sealing bath can rise sharply when there are a lot of plates in the tank. The temperature can also drop because multiple plates are being immersed in the bath at the same time. This is when it is most likely that colours will bleed out. It is recommended that you move plates to and fro for the first minute of the sealing process. The pH value of the water in the tank is also an important factor in this respect. The pH value should remain between 5.5 and 6.3. If the water becomes too acidic, then it needs to be neutralized using sodium carbonate, and if too alkaline, using acetic acid. We stock pH test kits and litmus paper in our product range for this purpose. Sealing salt can also be added to create a buffer solution that helps keep the acidity level constant and prevent bleeding.