Polymetaal

Etching grounds Charbonnel

Etching grounds
The main constituents of the grounds:

• Judea bitumen: It offers chemical resistance to acid and gives an opaque and darkened hue.
• Waxes: Their hardness varies according to the properties of the wax. Waxes make the ground supple, avoid scaling on etching and produce a matt or satin finish.
• Dammar and Mastic resins: Transparent resins that increase the grounds' hardness. Their hardness allows etching with tools. Mastic resin is insoluble in white spirit.
• Essence of turpentine: It dries slowly and gives a semi-gloss finish to the grounds.
• Quick drying petroleum: It dries faster than essence of turpuntine and gives the grounds a more matt finish.
• Colophony: Increases the grounds' hardness and allows etching with tools.
• Pitches: Range from brown to black depending on their origin. Increase the grounds' hardness.
• Dry extract: Dry component (non-volatile) included in the above products. The higher the percentage of dry extract, the higher the non-volatile quantity of the product.

All these grounds may be thinned using quick drying petroleum, essence of turpentine and F-essence, except mastic grounds which must only be thinned using quick drying petroleum. They are applied with a soft and very wide brush or with a roller.

Before applying these grounds, it is imperative that all grease be removed from the plate. To do this, thin some Marly white with a small quantity of water and rub the plate with a soft cloth or a piece of cotton. Rinse under flowing water: Pour a soured solution of vinegar and salt on the plate. Rinse once again. Dry rapidly. Avoid putting fingers on the plate whilst carrying out these operations.

CHARBONNEL HARD BLACK BALL GROUND (solid)

Once the ground is applied and dry, the picture is etched with a hard point in order to expose the metal beneath the ground. The plate is then placed in a bath of acid to erode the exposed metal. Once the required bite depth has been attained, the plate should be taken out of the acid bath solution and dried and the ground removed with the appropriate thinner:

Judea bitumen, wax Dry extract: 100% Hardness: very hard

Finish: opaque matt Consistency: paste

Wrapped in a piece of taffeta which serves as a filter; the ball is rubbed on the pre-heated metal plate. Dab on the ground to obtain an even surface before smoking. The matt black finish obtained makes etching work very clear:

LAMOUR HARD BLACK BALL GROUND (massief)

Judea bitumen, Dammar resin, wax. Dry extract: 100% Hardness: hard

Finish: opaque matt Consistency: paste

This ground is used as above. It is, however; not quite as hard as Charbonnel ball ground.

ULTRAFLEX LIQUID GROUND

Judea bitumen, essence of turpentine, wax. Dry extract: 25% Hardness: hard Finish: satin translucent Consistency: liquid Apply it cold to the plate with a very supple brush, or plate coating device or pour it directly onto the inclined plate. Due to its transparen£y, it is suitable for a second application and reworking.

LAMOUR BLACK SATIN VARNISH

Judea bitumen, essence of turpentine, quick drying petroleum, wax Dry extract: 25% Hardness: hard Finish: satin opaque Consistency: liquid It is applied in the same way as Ultraflex liquid ground. It allows a long etching time with no risks of scaling. It dries faster than Ultraflex due to the presence of quick drying petroleum. It is also harder than the Ultraflex ground and, therefore, allows finer lines.

Soft grounds protect the plate. They are non-drying grounds, applied with a painting dabber or roller: Textures and materials pressed into their non-drying surface will lift off, leaving the metal bared, ready for the bite of the acid. The plate must be heated before application. The "Pencil Method" consists of drawing with a hard point on "laid" paper applied over the soft ground. The paper sticks to the drawn parts. After the bite of the acid, a pencil stroke effect is obtained.

CHARBONNEL SOFT BLACK BALL GROUND (solid)

A painting dabber is recommended for application. It is applied hot.

After leaving the plate in acid for the required time, remove the plate from the acid bath solution and remove the ground using the appropriate thinner: The amount of time you leave the plate in the acid depends on the acid's strength (measured using an acetometer), the room temperature and the depth you wish to give the stroke. The etching is then ready and on!y the finishing touches need be applied. A retouching ground can be applied to the plate which may then be retouched as required following the lines of the previous etching.

CHARBONNEL HARD WHITE BALL GROUND (solid)

Pitch resin, beeswax, colophony Dry extract: 100% Hardness: very hard Finish: transparent Consistency: paste It is applied hot, using a cloth ball or painting dabber: This is the hardest of all retouching grounds.

TRANPARENT LIQUID VARNISH

Beeswax, pitch resin, essence of turpuntine Dry extract: 18% Hardness: supple Finish: transparent Consistency: liquid It is applied cold with a paintbrush. It is slow-drying and lets the previous etching show through

DUROZIEZ BLACK RETOUCHING VARNISH

Bitumen, quick drying petroleum, colophony Dry extract: 50% Hardness: very hard Finish: very glossy opaque Consistency: liquid It should be applied in thin coats using a brush. It may also be used as ground for aquatint. It tends to become crumbly over time and should, therefore, preferably be used as soon as it is dry.

LIQUID SICCATIVE VARNISH

Beeswax, bitumen, ketone thinner Dry extract: 26% Hardness: hard

Finish: satin opaque Consistency: liquid

It is applied cold using a paintbrush.

These are used to rework a plate that has been etched deep enough by the acid. They protect the surface of the plate without flowing into the recesses. They are, therefore, used to give the etched lines greater depth due to a fresh exposure to acid.

LAMOUR SOFT BLACK GROUND

REBITING ROLLER GROUND

Beeswax, bitumen, mastic resin, essence of turpentine. Dry extract: 61% Hardness: hard Finish: satin opaque Consistency: paste

These are applied cold with a paintbrush. Applied to the back and the edges of the plate, they serve to protect these parts from the bite of the acid. They are extremely resistant.

LAMOUR BLACK COVERING VARNISH

Bitumen, essence of turpentine Dry extract: 25% Hardness: hard Finish: gloss opaque Consistency: liquid It is particularly recommended for aquatint techniques.

ALCOHOL VARNISH