Frequently Asked Questions (part 5)

All the FAQ sections can be downloaded from the Web at this URL:

Part 5 - Cosmetic and Cabinet Finish Questions.

Original FAQ editor: Hank van Cleef, Gerard Tel (; now hosted on Trevor Gale's site (mail: can be sent using this link). Frequently Asked Questions (Part 5)

Revision Date Notes
1.0 Oct. 15, '95 New section
2.0 Dec. 11, '99 Basic HTML added.

2.1 Mar 2, '00 Safety and cleaning materials info updated.

Part 5 - Cosmetic and cabinet finish questions

This section discusses some of the methods that can be used to clean and restore items in acoustic phonos antique radios, and other items. While the internal construction of phonos may be quite different than that of electronic devices, many of the cleaning issues are quite similar. Almost any old device requires a fairly standard cleanup involving removal of dust and dirt, internally as well as externally. The first step in restoring an harmonium (reed organ) or a piano, as well as a phonograph, music box, or radio, is to clean the item thoroughly, inside and out, and assess its condition. Very often, all that is needed is a good vacuuming, with the help of some small paintbrushes to loosen dirt, and a soap-and-water cleanup. Clockwork mechanisms, small electric motor mechanisms, and electric phono turntable, wire recorder, and similar mechanical transport mechanism generally need to have old "petrified" lubricants cleaned off, and reassembly with new lubricants.

Cabinet restoration depends on the method of cabinet construction and finishing. Items built in the 19th and early 20th centuries generally had wood "furniture" cases, finished with a shellac process. The introduction of synthetic varnishes in the 1920's meant a rapid change to use of synthetics for wood finishes, and shellac finish on a home entertainment device becomes rare through the 1925-40 period. Post WWII wood finishes are most commonly one of the urethane synthetics.

Plastics that could be formed by casting and injection molding processes became available at the end of WW I, and many home entertainment devices made in the 1920's have visible parts made of "Bakelite," a phenolic resin with an inert filler that can be injection molded. By 1940, there were a variety of thermoplastic (i.e., melts when heated) and thermosetting (i.e., cures under heat and does not remelt) resins were commonly used in construction of molded radio cabinets, knobs, and decorative trim items. Many of the plastics used in the later pre-WW II period were not stable over long periods. Ultraviolet from strong sunlight and heat above human body temperature would accelerate distortion and discoloring, for which there generally is no repair other than replacement of the affected part. Items in good condition should be cleaned up and positioned where they will not be subjected to strong sunlight or heat.

Various metals are used both in internal construction and in cabinetry. Painted steel plates and cabinets are commonly found. Also stamped brass decorative parts. One very common process was to use steel and to electroplate it with a brass finish. Die cast white metal parts are commonly found. The zinc alloys used in the 1910-35 period produced excellent parts, but are subject to aging and corrosion breakdown. Typically, they will become larger, then become extremely brittle and crumble. Once again, the only "repair" solution is replacement of the affected part.

There is a long-standing myth that white metal parts were made of "floor sweepings" and scrap, and the term "pot metal" is sometimes used in the US to denote the material. This is not accurate. Zinc precision die casting technology uses specific alloys and processes, and produces excellent results. Some manufacturers used die-cast or sand-cast aluminum alloys after the mid-1920's. These should not be confused with zinc alloys. Die casting processes for both zinc and aluminum produce high dimensional accuracy, but require creation of an expensive metal mold set, so are generally associated with high-volume parts. The tooling required for sand casting is much simpler and less expensive, but the as-cast parts require machining of critical dimensions.

This is a very cursory overview of materials and processes, and the reader who wishes more information should search out and study some of the literature written for engineers and crafts people who work with these technologies. In particular, "Machinery's Handbook" and (in the US) the SAE Handbook (Society of Automobile Engineers) have extensive information on metals and manufacturing processes.

The original FAQ editor has some strong feelings about some of the techniques for cleaning and restoration that have been discussed on various newsgroups. There is no question that many restorable items have been ruined beyond repair by use of inappropriate chemicals and cleaning methodologies. Beyond this there are considerations of "kitchen chemistry." Almost any solvent or process has safety considerations to consider. And almost any solvent or process will damage something in a device. You may want to use it over here on this metal part, but if you get it on that plastic part or electronic component, in may destroy it. Additionally, there are issues of fire hazards, fumes, violent reactions with other chemicals, and safe storage to consider. Know your products, and know your processes.

A kitchen is a place for food preparation, not chemistry experiments or industrial processes! Be very careful to keep solvents where they cannot contaminate foods or anything used for food preparation. [The following safety notes are steadfastly agreed with by the current FAQ editor - who has also a photographic darkroom with its associated chemicals]. Store chemicals separate from food items, and away from the inquiring hands of small children. Also, do not use containers / bottles etc., which were intended for food and drink to store your chemicals in, unless there is no alternative, in which case clearly label such containers, removing or covering the original labels. Also keep in mind that many of the preparations sold in grocery stores for kitchen cleaning purposes are, in reality, very strong chemicals, and may have very little information on the chemical content or processes. When writing this, I checked a can of Dow brand oven cleaner. It acknowledges 4% sodium hydroxide as an active ingredient, and gives a litany of safety precautions in use. This stuff is more violent than most of the industrial cleaning processes I've used. Many of the spray can cleaning products are very easy to use----just spray them on your valuable antique and watch it dissolve before your very eyes. Remember that these are proprietary products, and while the labels may disclose a few "active ingredients," it is often not all that is in there that will wreak havoc. There is a steady stream of notes in the antique groups from people who tried a spray can kitchen product and discovered, too late, that it took markings, finishes, etc. off along with the dirt.

There are two manufacturers who make chemical products specifically for use around electronics equipment. Caig Laboratories makes "DeOxit," which is considered by many people to be about the best contact cleaner around. They make a number of other chemical products for various electronics uses, and provide good and specific application and use notes for their products. GC Electronics, formerly General Cement, make a variety of products for various uses. These include a good electronic coil dope, a chemical wire insulation stripper for stripping the enamel from magnet wire, and a variety of cleaning products and adhesives.

One "easy cleaning" method that gets tried regularly is use of a household dishwasher to clean things. Don't do it. Almost all dishwashers use high temperatures in their washing cycle, and the detergents used are a strong caustic solution. They may wash dishes well, but for other cleaning, have almost all the attributes and drawbacks of a hot caustic tank with few of the virtues. I've had the unpleasant experience of spending a day with precision machine tools reworking the castings in an automotive power steering pump that were put through a good household dishwasher.

General purpose solvents that are generally mild and easy and effective to use are:

1. Water, with or without soap. Water is actually the most universal solvent. A little bit of soap or detergent will increase its ability to wet the surface. More soap will make an alkaline solution. Safe on most things, but may dissolve inks used on dial markings, and should be used with care around electronic components, particularly iron core chokes and transformers. One of the better detergents to use is a generic-type dishwashing detergent such as Octagon brand.

2. Household ammonia. This should be the clear non-sudsing type, with no additives like lemon sent. Straight ammonia is a strong alkali, and will dissolve shellac very quickly. A mild ammonia solution generally does a good job of dissolving dirt on painted and metal surfaces. A plain ammonia solution without additives will dry without leaving a residue, and may be preferable to a soap/detergent solution for many applications where a thorough water rinse is not used.

3. 3M adhesive cleaner (an automotive product). This is a petroleum product sold for removing adhesive residue, road oil, etc. from automobile painted surfaces. It is safe on most plastics. Excellent for removing the residue left by old masking tape, cellophane tape, and removing adhesive labels and their residue. It's made by the principal makers of several adhesives, so is formulated for removing residues from their adhesive products.

4. Isopropyl alcohol. Generally sold as "rubbing alcohol." This is an alcohol/water mix, and sold in various concentrations. What I use is a 70% solution. Alcohol will attack marking inks and painted surfaces, but will sometimes cut adhesives and things like chewing gum that the 3M products have difficulty with.

5. Diesel fuel. Excellent for dissolving petrified lubricants and other petroleum products. It is not as quick as gasoline for this purpose, but has the advantages of being much less flammable, and leaves an oily coat in the part surface for several weeks, which will protect against immediate rusting. Generally safe with plastics and slow to attack painted surfaces. Diesel fuel is an excellent choice for cleaning spring phono motor parts.

All of the above are fairly safe and easy to handle. Except for soap solutions, all have distinctive odors. Ammonia generally requires ventilation or outdoor use, and diesel fuel leaves a strong "perfume" that is very slow to dissipate.

Noxious and violent chemicals that are excellent for some controlled applications. All of these require care and precaution in use and handling, and present serious safety hazards if not used properly.
I've added a good reminder on handling by Tom Walker who writes:-
"One thing I think should be added is to discard any rag and/or paper towel that you have used lacquer thinner with, [or any other flammable solvent - ed] OUTSIDE your shop or work area in a sealed metal can. These rags/towels can spontaneously combust! I've had two friends lose their body shops this way. Extremely hazardous in terms of fire, not to mention explosive!"

See below:-

1. Automotive lacquer thinner. This stuff will cut right through many things. It is also extremely flammable. Excellent for cleaning petroleum and oily residues off metal parts to leave them absolutely clean. Cuts almost all thermoplastics instantly, and will damage paint surfaces. Removes most marking inks very quickly as well.

2. Strong acids. Hydrochloric, nitric, sulfuric, and phosphoric acids all have good industrial applications. "Oil of vitriol" and "muriatic acid" are colloquial names for sulfuric and hydrochloric acid. All of them are extremely agressive and difficult to handle. A mild phosphoric acid product with good applicability for rust removal is sold as "Naval Jelly." Other than this, these chemicals are poor choices for use in antique restoration.

Solvent application methodologies:-
The best methodology for using any of the above solvents is controlled application, to assure that only the parts to be cleaned by the solvent come in contact with it. In most cases, soft cloths and Q-tips work well. The best soft cloths were cloth baby diapers, which have been largely displaced over the past thirty years by disposable diapers. Start by vacuuming off the loose dust. A small paintbrush and some smaller brushes, such as those sold for basting poultry, can help in loosing dirt. Follow up with a mild soap and water solution applied with a rag. A soft toothbrush can reach into inaccessible places and is particularly valuable in cleaning up knurled metal parts and fluted knobs. Use Q-tips moistened with solvent to reach into inaccessible areas and to "spot clean" specific areas.

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