Reverse glass gilding – Glass protects the gold leaf against scratching
In terms of the technique, the term reverse glass gilding speaks for itself. Glass or perspex panels protect the gold leaf against potential scratching. The gold leaf is stuck to the glass surface using an adhesive. Depending on the desired appearance of the gold and level of lustre, you can choose from various adhesives, such as gelatine, oil-size, Aqua gilding size or UV adhesive. Reverse glass gilding whereby different gilding techniques, lustres and gold colour tones are used is particularly striking.
Adhesives for reverse glass gilding
- Gelatine – is the secret behind brilliant reverse glass gilding. To prepare it, allow 1/4 of a sheet of Dr. Oetker gelatine to soak in one litre of cold distilled water for 30 minutes. A little tip: cut the sheet of gelatine into four pieces with scissors. Then carefully heat the solution over a bain-marie to a maximum of 50°C. Once the gelatine has completely dissolved, stir the warm solution briefly and then pass it through a coffee filter paper. Then add a drop of washing up liquid to the filtered solution. The adhesive liquid is not ready for reverse glass gilding.
Clean the pane of glass well and then apply the liquid adhesive to the surface. Apply gold or silver leaf to the wet glass surface using a gilder’s tip. Using a brush, coat the not-yet-gilded glass surface with the liquid adhesive once again to keep it wet, as the gold leaf will not stick to a dry pane of glass. Once the gilding work is complete, place a sheet of dry blotting paper onto the gilded surface and roll over it with a rubber roller, applying slight pressure. The remaining liquid adhesive will be pressed out and absorbed by the blotting paper. Then allow the pane of glass around 1 – 2 hours to dry. The gilded surface will then shine like a mirror and must now be carefully polished up with clean cotton wool. The gold leaf surface will generally have several flaws and translucent areas. Therefore, when gilding with gelatine, the process is then repeated, with the surface once again coated with adhesive and gilded.
- Oil-size – ideally suited for achieving reverse glass gilding with a silky sheen. The oil-size should be thinned with white spirit at a ratio of 1:1 and applied to the cleaned pane of glass. The surface is then immediately wiped off horizontally using lint-free paper towels. It is important a paper-thin and even film of oil-size be applied to the glass surface. The drying time for oil-size is not noticeably affected by thinning.
Allow the required drying time for the oil-size and then gild with loose or transfer gold/silver leaf. Once complete, the surface can then be immediately brushed over with a gilder’s brush and carefully polished with cotton wool*.
- Aqua gilding size – is suitable as an adhesive for matte reverse glass gilding. It is recommended that the gilding size be thinned with around 25 percent distilled water, and this can then be applied horizontally over the glass surface using a foam roller or brush.
The gilding can begin after a drying time of approx. 30 – 60 minutes. Both loose and silver gold/silver leaf are suitable for this work. The finished surface can then be immediately brushed over with a squirrel hair gilder’s brush and polished. Because the surface of the gilding size always remains very soft, it should only be very briefly brushed over and polished with great care.
- UV adhesive – enables new surface finishes when gilding glass. Apply UV adhesive evenly to the cleaned glass surface and then apply loose gold leaf. It is recommended that you work directly from the gold leaf booklet with a golder’s tip in order to place the gold onto the UV adhesive surface. Once fully gilded, expose the glass surface with a UV light. The adhesive hardens and the gold shines with a “crumpled” metallic appearance.
*Cotton wool: When polishing gold leaf, only use 100% pure cotton wool. Synthetic fibres in cotton wool scratch the gold leaf on the gilded surface and generally result in a total write-off.
Paint the reverse side: the majority of reverse glass gilding is painted on the gold side for the purpose of protection. Paint diluted with chalk or pigment additive is suitable for this purpose. This reduces the surface tension of the paint and prevents the flat layer of gold from coming away from the glass.