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INCIDENTS DURING THE PRINTING
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Nature of the incident
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Origin(s)
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Remedy (ies)
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| – During the inking, the coat of gelatin come unstuck, gets loose in some parts. | – Fat tracks on the glass paving stone during the operations of sprawling of the gelatin. | – Degrease completely the plate with pure ammonia water before crossing the adhesive sublayer, and not touching with fingers on this first coat before putting the bichromatée coat. |
| – The paving stone keeps a part of its ink, instead of to put down everything on the prints. |
– lack of pressure on the cylinder of the press. – Too hard ink. |
– Increase the pressure of the cylinder (regulation of the press). – Soften the ink by adding it one girl quantity of average varnish. |
| – The prints are too light, no detail in the dark parts, blacks lack depth (no halftone). |
– Gelatin underexposed. -Too wet gelatin, not enough charged in ink. |
– Unusable paving stone, because we cannot make come what does not exist. Begin again another sunstroke. – Wait a little that the paving stone dries, or to cross some sheets without inking. |
| -The paving stone takes a lot of ink in the dark parts of the image, onbres is too much darkened and have no detail, the whites cover themselves with a grey veil. |
– Too dry paving stone. – Too much exposed gelatin. – Too flexible ink (error during the preparation of the ink – > excess of added varnish). |
– Clean the plate, and proceed to a more prolonged wetting. – Unusable paving stone, because we cannot give her the necessary humidity. Begin again another sunstroke. – Restore the balance by modifying the consistency of the ink. Add it some harder ink, but no varnish. |
| – Spots, blackheads appear on the plate and prints. |
– Foreign bodies in the ink, or fallen on the plate during the printing (big dusts). – Dusts, foreign bodies included in the coat of gelatin. |
– Avoid the dust in the workshop. – Look after the filtering of the gelatin ; remove dusts which can settle on the plate during its sprawling in the drying oven (just before closing it). They are visible in shaving light. Remove them with the fingertip. |