Friday, February 6, 2015

Mirror Clock Project Part 2 - Gilding


Gilding is an important detail on early New Hampshire mirror clocks. Some have sadly been painted-over in gold paint over the years, while others have survived in brilliantly shiny condition even after 200 years. Here's an example of a wonderful clock that's still in excellent original condition:

When it comes to gilding, you have two basic methods that are used: oil gilding, and water gilding. Often the two techniques are used on the same piece for contrast. Oil gilding simply involves a quick drying linseed oil varnish (size), and the application of the gold leaf. In general, it produces a somewhat brilliant finish, but is slightly more matte than water gilding. Water gilding involves the use of animal glues, and clay boles, and the gold is applied with water. The water reactivates the animal glue in the prepared surface, which bonds the gold to the surface. It produces the most brilliant finish, and it can subsequently be brought to a highly reflective mirror finish (using agate burnishing tools).

If you are interested in a quick tutorial on water gilding, I would suggest watching this episode of the New Yankee Workshop:

How to make a Giltwood Mirror (24 min)

For this particular reproduction, I wanted a not-too-glossy gold finish, and I wanted the gilding to be antiqued and faded. I had also planned to use imitation leaf, which works best with oil gilding. That said, I still had to prepare the wood base in nearly the same way, using layers of sanded gesso, and a base layer of deep red.


When it comes to gold leaf, you have several options and brands available. Imitation leaf is also known as Dutch metal, and it comes in several different shades (Gold, Silver, Copper, etc). Most of the imitation leaf comes in sheets 5" to 5 1/2" square. Real gold leaf comes in various karats and comes in small sheets about 3" to 3 1/2" square. Both types of leaf usually come in "books" of gold leaf contain 25 leaves. In addition to "loose leaf" (which is my preference) there is also transfer leaf, which has the leaf attached to a backing paper, and it must be pressed in place. Price-wise, the current costs for imitation leaf (depending where you buy it) is between 10-20$, and the average price of a book of genuine gold leaf is around 50$ or more.

Shown below is my current inventory of gold and silver leaf. Two types of imitation gold, one package of imitation silver, and two types of genuine gold leaf (the top one is loose leaf, and the bottom one is transfer leaf).

Another thing to keep in mind is that apparently imitation leaf can go bad. I wasn't really aware of this, but since it's basically a metal blend that is close to brass, it can become tarnished, and even develop spots, as was the case in one or two sheets from the book I used below. These had been in a plastic bag (the original packaging) and stored in the basement for several years, so be aware of this.

Only the first two sheets were affected, and only on one side. They were used for testing and samples. The rest of the book seemed fine.

For this project, I decided to use imitation leaf, since I did not want to invest the extra money in the specialized clay bole, and rabbit skin glue which are needed for water gilding. I was also aiming for a more antiqued and distressed look, so the imitation leaf would work just as well.


Gesso is basically paintable plaster mixture which seals and smooths a surface in preparation for painting or gilding. Traditional gesso is a mixture of rabbit skin glue, whiting (chalk), and water. Recipes for gesso can be found easily online. I chose to use a pre-mixed acrylic gesso. You need to apply enough gesso to build-up a thick enough layer that you can then sand it smooth. I believe I applied about 8-10 coats of gesso on my turnings.

In this photo you can see one section of turning before and after sanding.

The sanding is NOT fun, and it's very time consuming. You want the gesso to be as smooth as possible, since the leaf will show all the imperfections. Since the door frame was fairly smooth, I did fewer coats (around 4).

In lieu of a red clay bole, I used a burgundy acrylic paint. The reason for the dark red paint is to give the gold a richer appearance, and as a background for any visible gaps and voids in the leaf. Other traditional ground colours for gold leaf include grey and ochre (mustard yellow). This was coat number 1:

The paint was a bit too transparent, and I had to do a lot of coats to get a nice deep burgundy. This was coat number 5:

I ended up doing 7 coats of burgundy to get a deep enough red. If I were doing this again, I would skip all this acrylic paint and just use an oil based burgundy spray paint. The spray paint would only need one or two thin coats, and it would give a smoother finish.

The paint was then polished down and smoothed as much as possible with #0000 steel wool.

The areas that won't be gilded are taped off with painter's tape, and the oil gilding size is applied. I made the mistake of applying ALL the size in one shot, since it was supposed to take 3 hours to dry, with at least 1 or 2 hours working time, however, the gilding took much longer than I had thought, and near the end, the size was nearly dry. The size I was using also came up to tack much faster than the 3 hours it should have taken. It was ready to use after only 50 minutes!

The imitation leaf is much thicker than real gold, and you can actually pick it up and handle it with your fingers without it falling apart or tearing. If you are using genuine gold, you must be very careful and gentle when lifting each piece using a gilder's tip. To cut the leaf, you are supposed to use a gilder's knife and cushion, but I simply used a sharp/thin palette knife, and a scrap of leather (suede side up). I don't plan to do a lot of gilding, so I'm not ready to invest a lot of money for the specialty tools that are usually needed.

Gilding finished, with the black portions of the columns freshly painted (one coat of black acrylic paint).

It was at this point that I decided to do a gold door frame, instead of a black door frame. I felt that the clock would be too dark, and most of the examples I found during all my research use a gold door frame.

Here is a close-up showing the gilding. I later went back and did some touch-ups on all of the large missed spots (especially in the cracks). You can see that a lot of the brush strokes from the burgundy paint show through the gilding (the surface ends up looking a bit wrinkled), and that it would have needed a much more thorough sanding for a smoother surface. Unfortunately Acrylic paint doesn't sand that well, and I would have been much better off with a red (oil based) spray paint as mentioned earlier.

To save time and to get a slightly different shade to the gold, I used black paint for the base colour on the door frame.

To make the least amount of mess, and to avoid scratching or damaging your leaf while you work, start with all the awkward areas first. I applied the gold on the door in multiple sessions. I did all the interior corners of the corner blocks first, followed by the interior lips (where the glass will sit), and lastly the exterior portions in 2 "L shaped" sections.

I waited until the very end to brush off all the excess gold overhanging edges and joints.

The centre of the door frames won't show under the columns, so you don't need to leaf the entire frame.

You WILL end up with gold flakes EVERYWHERE. Try to clean up as you go, and avoid any drafts (walk slowly, close furnace or AC vents, etc).

The tops of the corner blocks can be either black or gold. I chose black.

Topcoat your leaf, to prevent it from tarnishing, and to protect it. The topcoat will also serve as a barrier for the antiquing and glazes, and it will deepen the ebonized sections.

You can see much fewer imperfections in the final (sealed) leaf (compared to the previous detail photo earlier). I did want SOME imperfections to replicate crazing, scratches, etc. but not too much.

The next part will cover reverse painting the tablet.

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