Clock Case Special Finishes
 

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Restoring the case of an antique clock often requires a number of skills beyond those used in basic wood finishing. There are several "special" finish techniques that every restorer should be able to perform.

For example, gold leaf (gilding) was used extensively by many clock makers during much of the 1800's. Gilding was often used on the end caps of columns and on molding trim around glass. Complete column gilding was sometimes used and "rings" were impressed around the circumference of the column. Repairing and restoring gilded finishes is an essential skill for high quality restoration work. A brief example of Gilding of columns is detailed in this link. Chapter 6 of Extreme Restoration provides a more detailed explanation.

Another common finish was faux “tortoise shell” or “French ivory”. This was a frequently used treatment on the columns of shelf clocks. The original finish on many clocks shows exceptional depth to the shell effect. Recreating this finish is not difficult but requires a somewhat unusual approach.

 

 

Less common, but equally challenging, is the “simulated” wood finish used on the sides of a number of clocks built in the later part of the 1800’s. This finish is much more common than usually suspected.

When only a portion of a veneer panel must be repaired or replaced, it can be quite challenging to match the old and new. This often requires a special technique commonly called "faking". This is a technique for making unwanted veneer joints disappear and blend with the panel. Faking is not difficult, but does require practice and a good eye.

Chapter 6 "Special Finishes" has over 70 pages dedicated to restoring or recreating the most common special finishes used on antique American clocks. This includes gilding of columns and trim, tortoise shell finish and faux wood grain. Mastering these techniques will push your restorations to the next level.

 

Understanding The Different Types of Gilding

Gilding or gold leafing is an ancient art going back over six-thousand years. Egyptians were well versed in gilding as can be seen on artifacts recovered from ancient tombs. Ancient oriental artifacts show that gilding was also practiced in this part of the world from very early times.

 The use of real gold as well as imitation gold leaf (Dutch leaf) was common throughout Europe from the early middle-ages forward. Gilding was used for books, religious objects and in the homes of nobles.

Gilding was integrated into American clock case designs during the early to mid 1800’s to fit in with the Empire and Victorian furniture styles of the times.

Columns were often gilded as was the quarter-round molding around the glass in the door. The feet, side-arms and metal trim pieces used on black-cased clocks of the late 1800’s were usually gilded.

There are a number of different materials used for gilding. Both real gold leaf and imitation gold leaf have been used. There are also several different techniques that can be used for gilding depending on the materials being used and the finish desired. Understanding the available materials and techniques is the first step in determining the best approach for a given project.

Real Gold: Gilding with real gold offers one big advantage over imitation leafs: the finished surface will not tarnish or turn greenish over time as oxidation takes place. Gilding with gold leaf can be accomplished using one of two techniques.

Water-gilding: This is the original and oldest gilding technique. This technique uses a surface on which multiple coats of gesso have been applied then sanded glass smooth.  Next a red-clay “bole” is mixed into a paste and applied to the gesso.  This finish is also carefully sanded and polished.

Finally, the gold leaf sheets are carefully applied using a water/alcohol/size mixture to accommodate laying the sheets.

 A special gilding brush is used to pick up the gold sheets and apply them since the gold leaf is far too thin to be picked up by hand.

 An advantage of water gilding is that the gold finish can be burnished to a high luster resembling a single solid piece of gold. 

 While beautiful, water gilding was not the technique commonly used in American clock manufacture.  The process was far too time consuming and costly.

 

 

Oil Gilding: This is a technique in which actual gold leaf is applied using a “size” or glue mixture to hold the leaf in place.  With this technique, the wood is prepared with a gesso mixture as with water gilding.  The gesso is smoothed then covered with the sizing liquid. A bole coat is usually not used.  The gold leaf is applied using the gilding brush and is held in place by the size.

This technique is much easier to master than the water-gilding technique, but cannot be burnished to the high finish of water-gilded pieces. However, oil gilding applied to a very smooth surface can produce an excellent finish.  Oil gilding is often used on large scale and architectural projects

It is generally thought that gilding using real gold would have been too costly for mass produced clocks. This can be verified by closely examining the remaining gold finish on a clock case. Real gold does not oxidize and become dull and greenish. This is a quick indication that the finish was originally an imitation leaf.

Imitation-leaf: Gilding using a non-gold leaf has been around since at least the 1500’s as a decorative replacement for costly gold. There are a number of different types of imitation leaf including:

  • Abbyssinian Gold (alloy of copper and tin).
  • Ducat Gold (alloy of copper and aluminium).
  • White Metal (alloy of copper and aluminum).
  • Dutch metal (alloy of copper and brass).

Dutch metal leaf is by far the most common alloy used in gilding and is still commonly employed for gilding today.  It is the most likely gilding material used on antique American clocks.

Imitation leaf is supplied in leaf form (small squares) just as real leaf. A “book” of leaves is a package of leaves separated by tissue paper.  A number of different brands of imitation leaf are readily available from arts and crafts stores as well as from numerous internet sellers.

 

 

 


 

Transfer-leaf: There are several recently developed gilding products which are produced using the copper/brass composition seen in imitation leaf, but using a much finer mixture than previously possible.  A very thin layer of this mixture is deposited on a transfer medium such as cellophane.  It is then transferred from the cellophane to the object being gilded via a standard sizing solution. 

Imitation leaf and transfer leaf both have advantages and disadvantages.  Imitation leaf is available in many different brands and shades.  Finding a color that closely matches that of the original clock finish is usually possible.  A disadvantage of imitation leaf is that it is applied as individual overlapping sheets.  This usually means that small lines will be visible on the piece where the leaves overlap.  Carefully planning and applying the individual leaves can usually minimize visible leaf joints but this is still a point worth noting.

Transfer leaf offers a different concept than imitation leaf. The gilding material is lifted from its cellophane backing when applied to the work piece.  This means that there will be no joints between leaves.  Transfer leaf applied to a smooth surface creates an almost mirror-like finish close to a piece that has been water-gilded with real gold then burnished.  The negative side of transfer leaf is that there are fewer brands available and those available tend to have a more “brassy” or yellow look than either real gold or good imitation leaf.

Another thing to consider when choosing the leaf type is the end result desired.  Traditional imitation leaf is a solid sheet of material. When applied it usually provides 100% coverage of the underlying surface.  This can result in an “over-restored” or “too perfect” look. On the other hand, transfer leaf is applied by pulling the material from the backing. Often there will be small un-gilded spots which allow the under coat (usually red) to show through. This creates a more aged look. 

Both types of leaf can provide a very good gilded finish for clock restorations.  They are inexpensive and you may want to experiment with both.

Metallic Powders: An alternative to the use of gilding or leafing materials is metallic powders. Metallic powders are very finely ground materials such as mica or other minerals. There are many different shades of powder available. In fact there are over six different shades of gold alone. This makes matching an existing tone much easier.

Metallic powders are applied to a surface that has been prepared with an adhesive size similar to that used with leaf.

Metallic powders are very versatile and can be used to make a liquid paint or brushed on dry. The wide range of colors is very appealing.



A final note about imitation gold leaf and powder products; whether imitation leaf, transfer leaf or metallic powder, they must be sealed with a clear coat soon after the gilding is applied.  If not, the finish will very quickly begin to darken and tarnish as oxidation takes place.