User instructions for the hard universal etching ground Graphic Chemical.
Sorry, not in Spanish yet
The plate must be covered with a thin layer of ground. It is very important that this ground is applied correctly, since a bad ground can distroy all the work done. A thin ground will bite through very quickly at the wrong locations. If the ground is too thick, the varnish might crumble off at cross hatchings. This also happens if the ground is burnt too much: if overheated the ground becomes brittle.
If a line is drawn, with a needle, through a thicker part of the ground, the acid meets more resistance in the thicker part, making the lines thinner and less deep. In a section of the prints with many lines a clear distinction can be made between the thinner and the thicker ground. A print will also clearly show this, so an even distribution of the ground is very important. Dust is the ground's major enemy: around particles of dust the varnish seems to be thinner. Under a magnifier this shows clearly. A particle of dust is surrounded by only a quarter of the normal quantity of ground. The acid will penetrate easily, creating dozens of litlle holes. This is not always visible in the resulting print, but it is quite difficult to remove these spots when they occur.
If a liquid ground is applied to the plate, heating is not required. The plate is positioned on its side (tilted), and some liquid from the bottle is poured onto a saucer. It should flow easily: if it is too thick, dilute it with naphtha. It should not be too thin, otherwise the acid will break through too easily. With a dust-free brush the ground is applied on to the plate, striking from top to bottom. Dust is even more problematic with solid hard ground.
A simple way is the following: rest the plate on the fingertips of one hand, and poor some liquid ground in the middle. By turning and moving the plate, the liquid will cover the whole surface equally..Only when the naphtha is completely evaporated, the ground is "hard".
The plate does not have to be "smoked" as a dark pigment has been added to the ground. There is always enough contrast between the etch ground and the drawing. Draw with an etching needle (slightly blunted) to create the drawing. Etch in nitric acid (copper zinc), iron-chloride (copper zinc) or a copper sulphate solution (zinc): Bordeaux-etch.
Irritation can occur if exposed to the skin or lungs as the ground containt natural asphalt.
Wear protective gloves if the etching ground will be heated to more than 95°C (200°F). Ventilation is required to avoid inhalation of harmful fumes.
The ground can be very dangerous when swallowed. If this happens, do not induce vomiting, and contact a doctor immedialtely. Keep out of reach of children.