by Andrea Daley

Does anyone out there restore pot metal successfully? What do you do when a piece of ceramic or porcelain has been misaligned and improperly glued with adhesives that are irreversible. Have you ever attempted to glue a section of wood in place to find it has splintered or small sections are missing so it does not align properly? Lets take a look at each of these "hard to glue" situations. The key point is not only to get them glued back into place, but to give strength to the damaged area so the item is structurally sound.

Metal:

The most common occurrence of damage is to pot metal items. What is pot metal? Technically, I don’t know. Some say it is the scraps left over from other metals and thrown into a large pot heated up to its melting point and then poured into a form. A dictionary describes it as "Mainly a mixture of various light-colored alloys, especially pewter, containing much lead or tin. These metals are very soft and melt at a low temperature." Also, other metals that are strong enough to be braised or welded, usually need extra filling to recreate the part damaged in the weld or braise. In the case of these molded metals, once broken, the metal has stretched, around the edges of the break, so there is uneveness to the joint. Lamps are a typical example of the use of this type of metal. Frequently, a protruding part gets broken. When the broken piece is a functional part, then strength becomes a main factor. How do you create a structurally sound repair?

Ceramic:

A ceramic (meaning any fired clay, which could be pottery, that has a low firing point, to English china, which has a high firing point) that has been previously glued and then, for whatever reason, has come apart. The glue is not dissolvable with any stripper, and has become impacted in the nooks and crannies so the only way to remove it is to grind it off. This leaves two sides that do not match each other. How do you create a structurally sound repair?

Wood:

In most cases, when a chunk of wood is broken from a piece, it contains splinters, or small missing sections. Again, this prevents a glue joint from having strength. It is much easier to work with wood and add strength to a repair. Wood is soft and usually larger than ceramic pieces or functional accessories made from pot metal. The restorer has many choices of how to restructure the damaged area. Using the common solutions of doweling, setting a screw, or covering over, are some ways of adding strength to a broken piece of wood. But, every now and then, the wood restorer will come across a part that can not be repaired with these traditional methods. It may be an extruding wood carving on an ornate clock, or a finial on top of a highboy. Let’s say some previous restoration was made that now has come apart and the joints are left uneven. How do you create a structurally sound repair?

A solution to all of the above, is to make undercuts. Making an undercut will add strength so the item will stay together.

What is an undercut? It is a cavity, crevice or an underlying channel, that once a substance is pushed, poured, or applied into it and hardens, will not release due to the entrapment. Drilling a hole at an angle creates this entrapment. When the filler has hardened, even if there is no adhesion, the pieces are held together because of the undercut. This is the method dentists have used for years to hold a filling in place. The dental field does not use adhesives. Their skill is to create undercuts (see diagram below), so the filler, once hardened, maintains it’s strength for years and years. The steps are the same: 1. Clean the surface. 2. Drill a hole at an angle to create an opening that a substance can be worked into (this is performed on both sides of the item or section to be secured). 3. Apply the adhesive or filler. 4. Place both edges together and let harden. This method is recommended when two pieces are being glued that need extra strength, due to poor adhesion or for functional purposes. This will be a judgement call for the restorer. This method is not used for every item that is glued.

In my own personal experience, I have repaired items such as metal lamps, bronze statues, and even an air conditioner lever in an automobile using this method. Once realized, the only thing that stops us from solving a problem, is our own imagination, then possibilities will present themselves that otherwise would not have been available. You just have to think out of your common zone. I don’t know how else to say it. Most people think there are rules to go by. A 1, 2, 3 step process. There are no rules. The greatest restorers are those who allow themselves to use their imagination and improvise.

Many times in order to secure two metal parts, a hole can be drilled through both pieces and then a groove cut to allow a heavy gauge wire to tie the two pieces together (see drills for recommended attachments under Convention Supply list). Sometimes a screw can be used to fasten to pieces. Be sure the head of the screw is countersunk so you can cover over it with the two part epoxy filler. I use a substance called "Plumber Seal" made by Atlas Mineral Co. (see Convention Supply List), which works great with metals.

The filler can be one of many choices. Wood putty or automotive body filler, epoxy two-part putty for metals or porcelain. They come in different consistencies, setting times and hardness. Experiment with different brands and use the one that works best for you. For a metal item that can be welded or braised, a two-part epoxy can be used over the repaired section to fill in, smooth out, or build up missing pieces. It hardens like steel,and can be sanded and painted to match. The point is, do whatever it takes to get the two pieces secured with undercuts, then fill over the repaired areas with filler, then sand smooth to create the surface to be simulated. To complete the process the restorer needs to develop the skills to create the look of the patina, the depth of color and matching the color and finish to the eye. How To Simulate A Finish. Next Restorers News.