After some troubles and a quantity of trials with Grayscale step wedges, here is my first Heliogravure image. The plate measures 145x165mm and the image 120x120mm. I have used an stochastic screen digitally designed and printed on high contrast photographic film in a Pre-press service bureau. The digital image was edited in Adobe Photoshop and …
Heliogravure III – Ultraviolet Light with Digital Screen
Updated 26/01/2016 Hardening the gelatin. In heliogravure, it is necessary an illumination source rich in ultraviolet (UV) light. This UV light must provoke the cross link reaction into the gelatin previously sensitized with potassium bichromate (K2Cr2O7). This reaction is explained by several and sometimes slightly different theories. Luis Hernández (2), explains that the UV light …
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Heliogravure II – Stochastic Screen
The Aquatint Screen As described in the technique of heliogravure, it is necessary to have some screen to illuminate the gelatinized paper or carbon tissue in order to bypass the use of a resin or asphalt aquatint. The resin or asphalt powder is applied by means of the called resin or aquatint boxes, where the …
Heliograbado III – Luz Ultravioleta
Endurecimiento de la gelatina En el caso del heliograbado, se necesita una fuente de iluminación rica en rayos ultravioleta (UV) que provoque la polimerización (cross link) de la gelatina sensibilizada con dicromato de potasio (K2Cr2O7). Según Luis Hernández (2) la luz UV actúa sobre la gelatina dicromatada generando un efecto de curtido. La reacción consiste …
Heliograbado II – Trama Estocástica
La Trama de Aguatinta Como se describía en el post anterior, es necesario disponer de una trama a través de la cual se insola el papel gelatinizado, simulando con ello el graneado de la plancha que se obtiene mediante la aplicación de asfaltos o resinas pulverizadas. Esta aplicación se suele hacer en las llamadas cajas …
Carles Mitjà - ASIS/FRPS 