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Superimposing one colour onto another so that the first down does not lay properly before the next colour is printed.

Causes: 

– Incomplete drying of the first colour down prior to printing the second down colour;

– Excessive plate to substrate pressure of first down colour;

– Dyes may cause some plasticisers o migrate;

– Second colour not printing due to:

1. I Low viscosity;
2. Ink drying too fast;
3. Low or high pH;
4. High holdout of substrate.

Solutions:

– Increase drying speed of ink, use faster evaporating solvents, balance dryers, reduce ink viscosity or reduce ink film with better metering. Decrease anilox volume and/or decrease dryer tem­perature;

– Reduce impression pressure of first down colour;

– Do not use dye-type inks with plasticised substrates;

– Second color solutions:

1. Increase second down ink viscosity to higher than first down ink;
2. Slow down drying by adding slower solvents, stop­ping air or heat blowing on plates and increase machine speed;
3. Adjust pH to specifications;
4. Change substrate, reduce ink film thickness or increase drying capacity.