Kölner Colnasize is a concentrate and an easily prepared size designed for the adhesion of gold and silver leaf to Kölner Burnishing Clay and Kölner Insta-Clay.
Dissolve one measured teaspoon in two cups of lukewarm tap water. It is not necessary to use distilled water.
Some application techniques and climate conditions may require a stronger concentration. If initial tests do not produce the desired results, the concentration may be increased to two measured teaspoons per two cups of warm water. Tests should be conducted at various concentrations until the desired results are obtained.
Prepare size in a clean, glass container, with a tight-fitting lid. Decant the amount you plan to use immediately. Don’t pour contaminated, used solution back into the original, pure solution.
Use a soft, natural hair mop brush to flood the surface. More than one application may be necessary to maintain complete wetness until the leaf is floated onto the surface. Apply leaf rapidly while surface is wet. A small brush will help apply size to faults or “holidays” in the gilding. Use small pieces of leaf to gild and patch.
Burnishing is a magical, yet sensitive technique that requires careful observation and practice. This method involves gentle pressure which compresses the gold and the clay layers. You are aiming for a mirror-like reflection. If you try to burnish too soon, the leaf will pull from the clay, and will have a dull appearance. Depending on temperature and humidity, you may wait as little as an hour and a half before beginning to burnish. Burnishing with the Kölner system generally requires gentler pressure than traditional water gilding.
Store Kölner Colnasize Concentrate and the prepared solution in a refrigerator.
Kölner Burnishing Clay
All surfaces should be smooth, clean, and free of dirt, dust or grease. Absorbent surfaces require a sealer before application of Kölner Burnishing Clay: matte board, porous paper, parchment, raw wood, textiles, unglazed ceramics, porous stone, plaster, traditional picture frame gesso, compo ornaments. A high quality dewaxed shellac may be used to seal.
Non-absorbent surfaces require no sealer before application of Kölner Burnishing Clay: Plexiglas and other plastics, glass, sealed wood, non-porous paints, and metals (which may require primer). Other sealed surfaces and smooth metals may require light sanding to promote good adhesion.
Do not use Kölner Burnishing Clay over traditional water gilding without first applying a barrier coat of shellac. Do not use Kölner Burnishing Clay to patch chips in traditional water gilding, as the systems are incompatible over time.
Kölner Burnishing Clays are used at room temperature. Prior to use, they should be thinned slightly with water, in the following ratios:
100ml (3.40z) Kölner Burnishing Clay add 0.25 oz of water
500ml (16.90z) Kölner Burnishing Clay add 1.25 oz of water
1 Liter (33.90z) Kölner Burnishing Clay add 2.50 oz of water
Stir the clay gently but thoroughly, avoiding air bubbles. Decant the amount of clay you plan to use immediately.
Use a soft, natural hair brush to apply clay in long, flowing strokes in one direction. Allow each layer to dry thoroughly before the next coat is applied; average drying time is a half to one hour. Color lightens and is matte when dry.
A minimum of three coats should be applied, further coats may be desired. It is not necessary to sand between coats. Sand with a high quality emery, aluminum oxide or wet/dry silicon carbide paper. Start with 400 grit and finish with 600 or possibly 800 grit paper. Dry sand only.
Burnishing is a sensitive technique that requires careful observation and practice. This method involves gentle pressure which compresses gold into the clay and gesso layers. There is a limited window of opportunity for burnishing. With practice, you will learn to gild only as much as you think you can burnish in a given time. You are aiming for a mirror-like reflection. If you try to burnish too soon, the leaf will pull from the clay, and will have a dull appearance. If you burnish too late, the leaf will crack, or streak with inconsistent shine.
Depending on temperature and humidity, you may wait as little as an hour and a half before beginning to burnish. You may have only a short time to burnish. Burnishing with the Kölner system generally requires gentler pressure than traditional water gilding.