As I mentioned in my last post, I’m learning how to use gold leaf with a technique called raised gilding. The cool thing about raised gilding is that the gold leaf is, well, raised – it is 3-D, so the light really glints off the gold. Photographs don’t do it justice – if you ever have an opportunity to see raised gilding in any context, you really have to see it in person to see how shiny it is.
What makes raised gilding work is the gesso. Gesso is a mixture of white lead, slaked plaster, and glue (along with a few other ingredients) that holds the gold leaf to the page. Gesso has to face an amazing challenge: it makes a 3-D surface on top of a piece of paper or parchment. The paper or parchment has to be able to bend underneath it, without the gesso flaking off. So the gesso has to be both 3-D and flexible.
If gesso is prepared just right, it ends up with an amazing chemical composition that allows it to have both shape and flexibility. If you’re interested in the chemical properties of gesso, the expert on the topic is Jerry Tresser. In fact, if you’re interested in raised gilding at all, he’s the guy to talk to. You can read his book, The Technique of Raised Gilding, or visit his website. Jerry is an incredibly kind and patient man, and has helped me immensely in learning how to use gesso.
To use gesso, you first apply it to paper or parchment using a nib or a brush. It’s a fairly thick substance, and it has a tendency to want to pool to itself. You make little mounds of gesso in the desired shape on the paper.
Once the gesso is dry, the polishing begins. Lots and lots of polishing. The gesso needs to be completely smooth and shiny – once the gold is applied to it, the gold will take on the exact shape of the gesso, and any imperfections in the shape of the gesso will be immediately obvious. So you polish. And polish and polish and polish. I’m using a burnisher made of agate. It takes a lot of pressure, and a lot of polishing.
Gesso can be pretty forgiving, though. If you make an mistake in it that can’t be polished out, you can moisten it and add more gesso to smooth it out. And you can polish out a lot of mistakes.