Imperial Home Page -> Imperials By Year -> 1968 -> Bronze Restoration -> Part 2
Cleaning of the metal plates was actually not the daunting task I thought it would be. Cleaning the bronze of tarnish was actually the easiest part of the process. The old lacquer was not as difficult to remove as I had anticipated and it did not require the use of strong chemicals. During the cleaning process it is also important to work carefully, as the bronze is very susceptible to scratches and marks.
- Steel wool - Medium course and 0000 grade.
- Rubber gloves - Here I used disposable vinyl gloves. These are the kind used in hospitals and also available at some building supply stores.
- Citrus Strip - This is a product used to remove paint from wood and metal surfaces. This product does not have a foul odor and worked well to remove the old lacquer. Cleans up with water.
- 3M Brand Copper & Brass Cleaner - This is a liquid product that did a great job removing the build up of tarnish. It is a heavy liquid and available at many stores. Contains no abrasives so will not scratch the surface.
- Paint Brush - I used a 1" brush to apply to stripper to the metal.
- Metal container - Just something to hold the stripper when in use. I found a can with a lid.
To clean the bronze of the old lacquer and tarnish I set up another table and covered it with cardboard. One side of the table was set up for the stripper and the other for the tarnish remover and polishing. I wanted to keep the striping chemical separate from the other processes.
Citrus Stripper is a product made from concentrated citric acid. It is a whole lot less caustic than other chemical strippers and smells a lot nicer when you are working with it. It will not burn your skin as easily as other chemical strippers but do be careful. It will still burn your skin if you leave it on long enough! I worked a couple of pieces of bronze at a time. Once the metal is exposed to air it will begin to tarnish so it is a good idea to only begin the pieces you can finish.
The stripper took off the lacquer quite well. Brush the stripper on using the 1” brush. You will know it is ready to remove when the surface is covered with tiny bubbles. It takes about 10 minutes to see results. I wiped the old finish off with paper towels. You will see any lacquer that was not removed. Reapply the stripper and repeat until all the old lacquer is gone. Leaving the stripper on the metal for long periods of time (like overnight) is not recommended. The stripper will dry out loosing its effectiveness. I also noticed that if the stripper stayed on the metal too long it would begin to spot the metal. The spots will come out with some extra effort but it is best to avoid this situation if possible.
Once the piece has been stripped of the old lacquer wash it in clear water. This will remove the stripper. I also used the stripper to loosen and remove the old glue from the back of the metal. The putty knife worked well to scrape off the loosened glue. Dry the metal with a soft cloth.
Now that the metal is free of old lacquer it is ready to remove the tarnish. Depending on the amount of lacquer that was on the metal, the environment from which the car has endured, and the level of care, there may be some really dark areas. My car had a few of these blackened areas where the lacquer had worn particularly thin. Tarnish is a process whereby the metal reacts with the atmosphere. If not removed tarnish will deteriorate the metal. Overall the bronze in my car was in good condition but there are a few places were the tarnish has stained the metal. The darkened areas will require some work using the steel wool. The 3M product works well to remove the years of tarnish that have accumulated on the surface. I covered the piece with the liquid, let it stand only a couple of minutes, then massaged the piece with my fingers. It did not take much effort to remove the majority of the tarnish. Wash the piece in clear water to remove the cleaner. Some pieces will not require the use of steel wool, which is a blessing. The less you need to handle the piece the better. The bronze has a brushed finish that is easy to damage with scratches. I found it is a difficult task to remove some marks from the surface.
To clean the pieces of dark stains I again used the tarnish remover. Along with the remover I used the 0000 steel wool. Begin using the least abrasive method to avoid creating scratches. Work the steel wool along the surface of the metal going in the same direction of the brush lines! I cannot emphasize this enough! If you make lines going in any other direction it will be difficult to erase these mistakes! Use the tarnish remover with pressure to work out the problem areas. I frequently washed the metal to see the progress. The remover tends to dry so you will need to add more as you work. Soon you will find the correct amount so that you can clean the metal and still see what you are doing. Hold the piece securely as you pull the steel wool across the surface. Work slowly. This is when being patient is definitely a virtue. Working slowly with the steel wool will save you from having to spend additional time fixing mistakes. Almost all of my darkened areas cleaned away. Some areas left a slight outline of the old tarnish stain. Success on removal will probably vary depending on how long the metal has been exposed to the air and your level of patience. I am not sure all stains can be completely removed. Work to your level of satisfaction.
Once the metal has been cleaned of tarnish it may need some work to remove scratches. Because the metal is soft it may have been damaged from years of neglect or abuse. Some stray scratches may have also appeared as a result of the cleaning process. Some of this can be corrected by using the medium grade steel wool. It does not take a lot of effort to create a brushed appearance on the metal. I did not use anything rougher than medium grade steel wool. The most important part of the process is to hold the metal straight and secure! The brush strokes go in a horizontal flow across the car. Inspect your pieces carefully before you begin. Observe the brush strokes and match them accordingly. I found a piece of cardboard that had parallel lines. I placed the edge of the metal parallel to the lines and used that as a guide to pull the steel wool straight across the surface. Shallow scratches will work out with a few strokes of the steel wool. It is best to work pulling the steel wool in one direction! Avoid a back and forth action. Start and stop your pull well before and well past the metal. Watch for stray pieces of wool and remove them often. These little stray strands will also cause scratches going in the wrong direction.
The scratch erasing process is tedious and time-consuming work. It is extremely important to work slowly and deliberately. I turned the piece end-to-end so that strokes could be over lapped and any marks from starting and stopping could be minimized. The medium grade steel wool will give the appearance of the original brush strokes. Smaller pieces and thinner pieces are more difficult to hold and polish so exercise caution. Clean the piece again to remove any steel wool dust. I did this under running water so that the dust would be rinsed away to avoid scratches from a cloth. You should now be ready to spray your bronze with a fresh coat of finish which we will cover in step three.