Radio Cabinet Restoration

Radio Cabinet Restoration

by Joe Koster


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A Brief History of MAARC

A Brief History of MAARC

by Brian Belanger


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The "Catalin Corner"


by Ed Lyon

Some people call them Bakelites, some call them Colored Bakelites, some call them Catalins, but whatever you call them, they are colorful little radios made of cast phenolic plastics. The Catalin Corner logo picture, at the left, shows a variety of these beautiful radios. MAARC has always published a fine newsletter, and one of the all-time favorite series of articles has been the 27-part series called “The Catalin Corner.” MAARC’s library services can supply back issues of the newsletter, called The Mid-Atlantic Antique Radio Club Newsletter until June 1994, thereafter called Radio Age. The Cumulative Index can guide you to the various issues that carried “The Catalin Corner.” This web site will also carry illustrated versions of those articles, so stay tuned.

Catalin was a trade mark name of the cast phenolic made by The Catalin Corporation. Today, the only things still made of cast phenolics are the finest billiard balls, the finest computer track-balls, ball-valves used in food-handling processes, and ball bearings for heavy tank turrets. But during the heyday of Catalin, from 1938 to 1946, everything that was more desirable in a bright, warm color was made up, even if for but a short time, in this plastic. Even the huge colorful curved illuminated panels in Rock-Ola and Wurlitzer juke boxes were made of the stuff, and there were many radio cabinets made of Catalin. The picture to the right shows a Rock-Ola "Magic-Glo" from the mid-forties.

The bright attractiveness of Catalin brought several competing brands out of the woodwork, as well. Bakelite Corporation made it, calling theirs “Bakelite Cast Resin,” as did Fiberloid Corporation, a company bought out, in 1939, by Monsanto, calling theirs “Fiberlon” and “Opalon,” and the little Lancaster, PA, company called Knoedler also made a version of cast phenolic, using theirs primarily for drawer handles, umbrella handles, and kitchenware. But the “Big Gun” in cast phenolics was always The Catalin Corporation, and they called their version simply “Catalin,” since they were first on the market.

But what is Catalin, anyway? And why is it so rare and so expensive? Why does a 1940 radio made of molded Bakelite cost, maybe, $20 today, while the same radio in Bakelite Cast Resin or Catalin costs 40 to 50 times as much? When you’ve seen here just how difficult it was to make radio cabinets out of Catalin, you will understand that this plastic was always expensive, and items made of it were relatively few in number, compared with molded plastics. One additional factor in today’s cost difference is the relative fragility of cast phenolics, with respect to molded phenolics. Catalin-type plastics shrink in size with time, averaging about 4% shrinkage over the first ten years of life. In a radio cabinet, if the radio’s steel chassis had been bolted firmly to the Catalin cabinet bottom, the shrinkage of the cabinet and the unyielding quality of the chassis often caused a crack in the cabinet. 

Part 1 - Comparing the Manufacture of Molded Phenolic with that of Cast Phenolic

To gain an understanding of the large differences in manufacturing costs involved in making radio cabinets we will compare similar cabinets made of Bakelite phenolics, the first one being a molded phenolic (resin plus filler) cabinet, the second made of Bakelite’s brand of Catalin-type cast phenolic.

Molded Bakelite radio cabinet

Common molded phenolics start out in a reactor vessel, a huge stainless steel or nickel-lined copper kettle with a tight-fitting lid, a steam jacket for heating it, and a cooling water jacket for cooling it. Inside are motorized stirrers for keeping the contents mixed and uniform in temperature. Phenol and formaldehyde, plus an alkali catalyst, are introduced into the reactor and the stirring begins, along with some heat from the steam jacket. Suddenly a reaction starts between the phenol and the formaldehyde, and, since the reaction is exothermic, it starts really heating up.

The temperature sensors in the kettle sense this heat formation and signal the start of cooling water flow in the water jacket, and a shut-down of the steam in its jacket. The reaction continues, and steam is produced from the heat and the water formed in the reaction. This steam is drawn off by vacuum pumps, and the reaction turns the contents into a molasses-like brown syrupy resin, which is neutralized by a strong acid, and is eventually poured out into big pans where it solidifies into brittle brownish flaky sheets of hardened resin, called novolak, very similar in appearance to peanut brittle. This resin is powdered by rolling mills and then is mixed with a filler material. If it is a batch of radio cabinets that is the ultimate product, the filler might be finely ground walnut shells, fine sawdust (wood flour), a mix of brown dyestuff and wood flour, or possibly some charcoal and wood flour. The ratio of resin powder to filler is about one to three or one to four.

Then a carefully measured quantity of this powder mixture is forced into a cavity in a heated steel mold, using a pump. The pressure required here is of the order of 10,000 pounds per square inch. The powder mixture heats and liquefies in this environment, and is forced throughout the cavity in the mold. There it hardens, after about ten (or more) seconds, into the finished product, in our case, a radio cabinet. The heating (to the melting point) of the powdered resin mix going into the mold causes an irreversible chemical reaction in the resin, first liquefying it, then hardening it, forever.

The mold is often made of heavy steel interlocking parts, so that it can be disassembled to remove the product, and yet is strong enough to withstand the molding pressure. Upon removal from the mold, the cabinet is completely finished, needing only a quick once-over to remove the paper-thin “flash,” remnants of resin that have oozed into microscopic seams between parts of the steel mold. 


Bakelite Cast-Phenolic (Catalin-type) radio cabinet

Bakelite phenolic casting resin, or Catalin, starts out as phenol, formaldehyde, and an alkali catalyst in a reactor, much like the molding phenolic above. The difference is that the water which is produced in the exothermic reaction of the phenol and formaldehyde is not drawn off, and the alkali catalyst is neutralized very carefully, not by a strong acid, but by lactic acid (yes, the kind that is in buttermilk), The result is a syrupy almost transparent resin which stays liquified. It is dyed the desired color and poured directly into a casting mold, made of lead. If a mottled or swirled color style is wanted, a little of a different batch of resin, colored white, for instance, is swirled into the mold by a worker, using a glass stirring rod. But we should say a word or two about the lead mold, before continuing.

The lead mold is a story unto itself. We begin with a solid steel replica of the radio cabinet machined out of a solid steel billet, the replica being called an arbor. The front of the cabinet replica is extended and thickened, forming a heavy steel plate, with the cabinet-like sides and rear opening sticking out of it. One of these arbors is shown on the right. It happens to be the arbor for the Emerson AU-190 radio. While the arbors are designed by and for the phenolic company, such as The Catalin Corporation, they are paid for by the radio company, in this case, Emerson. Thus the radio company controls the use of the arbor, preventing The Catalin Corporation from selling identical cabinets to other manufacturers. (We will see, later, how this prohibition was overcome from time to time.)

The arbor is highly polished (not rusty like the one in the figure), with a large handle on its topside, which is the flat plate forming the “front” of the radio cabinet. It weighs perhaps 80 pounds, so it is lifted, using its handle, by a hoist system, using chains or cables. It is swung over a heated vat filled with melted lead, and suddenly dunked into the vat and quickly withdrawn. A coating of lead freezes in place on the arbor, which, with the lead coat, now weighs perhaps 130 pounds.

An example of an arbor being lead-dipped can be seen at the left, the picture taken from a pre-war text on plastics. The lead-clad arbor is then slammed downward between two anvils which catch the outboard portions of the extended plate forming the radio front. The lead coating slides off the arbor, and is caught in a padded base between the anvils, so that it is not damaged. Now, the lead has a cavity in it, exactly the shape and size of a radio cabinet.

We noted above that the liquid resin is poured into the lead mold, sometimes with a dollop of another, differing-color, resin swirled into the mold crevices as well, to add a mottling color to the end product. A quantity of filled lead molds is lined up in rows on a steel pallet and the whole is wheeled into a huge oven, as shown at the right. Carefully temperature-controlled at 176° F., the oven cures the phenolic resin in the molds over the next three to eight days, depending on the color of the resin mix. Darker colors, like blue and red, cure in three to four days, while whites require six or eight days. At the end of the cure cycle, the pallet is wheeled out and allowed to cool sufficiently for handling.

Each lead mold is flipped on its side and air hammers are used to tap the radio cabinet out of the lead mold, by hammering on the edges of the cabinet, directly through the soft lead. Usually, the cabinet comes out of the mold unscathed; sometimes it is broken up in the process. The picture (below, left) shows the typical Catalin pieces (square rods) being hammered out of their lead mold. The lead mold is always damaged in the process, and is tossed into the molten lead vat for re-use. The picture (below, right) shows a typical firebrick-clad lead pot, filled with used lead molds, ready for re-melting and re-use. The molds had been used in a production of Catalin rod stock.

Part 2 - Differences in the End Product – Molded vs. Cast Phenolics

So we have seen the differences in manufacture, between molded and cast phenolic radio cabinets. Let’s see how the end products differ. The molded phenolic cabinet must be of a dark color, because the resin (novolak) which it starts with is brown. Any filler material might lighten the color a little, maybe to a tan or yellow-brown, but usually two powdered resin mixes are used, one dark and one lighter, to produce a swirled “walnut” color in the cabinet. Some radio cabinets were painted after the molding was completed, using a baked-on automotive enamel (remember that the molding process transforms the resin into a permanently-solidified plastic which cannot melt under heat, so that baking enamels are well tolerated by the cabinet). The cabinet finish is smooth and polished, owing to the fine finish on the steel mold parts. The cabinet thickness, it will be noticed, is uniform, and thin. It must be uniform in order to get a simultaneous chemical cure throughout the cabinet (otherwise there may be undercured [gummy] areas where the cabinet is thicker, or overcured [cooked or charred] areas where it is thinner than usual).

The Catalin cabinet stands out because of its color, its thickness, and its polished “feel.” It is usually brightly colored, a feat made possible by the relative transparency of the basic phenolic casting resin. This resin characteristic, along with the fact that no added fillers are used, makes the cabinet appear translucent, as well as brightly colored. The lack of fillers makes cast phenolics somewhat less strong than molded phenolics, so that the Catalin cabinet will be made with thicker walls than its molded cousin. The fact that the cabinet is cured over a four- to six-day period means that the thickness can be left to vary throughout the cabinet, according to what the designer wanted, unlike the constant wall thickness requirement imposed on molded phenolic cabinets.

After fifty years of storage, packing, unpacking, and handling, the kind of treatment expected of all household good, let’s again compare the two radio cabinets. The molded phenolic cabinet, let’s say in mottled walnut color, might be dirty and a little bit dull in finish, but is probably intact, with no chips, cracks, or warping of the cabinet. After a good cleaning, maybe using GoJo and a million paper towels, followed by polishing, using a wax-based fine rouge polish and a million rags, it will look like brand-new. If only the dial lens, knobs, and chassis could be made to look this nice!

The Catalin cabinet, being less tough (the only reinforcing filler in the cast resin is the water retained in its manufacture – and this water is in the form of microscopic droplets having some strength, but not a lot) because of the lack of fibrous fillers found in the molded phenolic, might be cracked or chipped. If the radio chassis had been tightly bolted to the cabinet bottom, the cabinet is very likely to be cracked now, fifty years later, just because the cast phenolic is certain to shrink, and the chassis is certain not to. Result: cracked cabinet bottom. Maybe the cabinet is made of two pieces of Catalin – a basic cabinet and a bezel or dial surround fitted into a hole in the cabinet front – and maybe they are of different colors – and just maybe the two Catalin pieces did not both shrink exactly the same amount over the next fifty years. Result: either the cabinet became cracked, or the inserted bezel fell out and became lost.

This very basic difference in viability is another reason the Catalin cabinets are more expensive today. This problem is aggravated by the fact that there really is no effective cement for cast phenolic plastics – except the phenolic casting resin itself.

Part 3 -  Colors !


FADA 252

Above: "As-found"

Below: Restored

You’re probably wondering, “What’s with the Catalin colors? Why are so many things ‘butterscotch’ or ‘pumpkin?’” Ultraviolet light, that’s what. All those radios and knife handles you see in ‘butterscotch’ color these days started their lives as white plastic. In many cases it wasn’t plain white, but heavily marbleized white, having streaks of transparent swirled throughout. But the phenolic resin itself is chemically converted to phenyl alcohol through the action of ultraviolet (UV) light – and phenyl alcohol is brownish in color. That’s the bad news. The good news is that phenyl alcohol is an excellent UV block, so that its presence on the plastic surface prevents the UV light from penetrating into the Catalin cabinet walls; thus the yellowing effect is only skin deep. This yellowing effect turns the whites (Catalin Corp. called their white phenolic ‘alabaster’) into dull yellow, or butterscotch. It turns bright blue (Catalin called their blue ‘lapis lazuli’) into a dull olive drab. What was originally green onyx is now deep butterscotch, and that brilliant red marble is now brown. All it takes to restore a cabinet to its original color scheme is very fine and careful abrasion with a wet (250-400-grit) abrasive paper, followed by restoration of the polished finish, through buffing with rouge and wax. One of the Catalin Corner articles in Radio Age detailed the method of color restoration.



A freshly-broken piece of 50-year-old Catalin, butterscotch on the outside, white inside.

The original makers of Catalin-type cast phenolics knew something about colors – which ones were more or less permanent, and which were so temporary that they didn’t survive the oven cure of the plastic. Some green dyes, especially, were apt to fade over the years, so that by now they are nearly transparent. It might be the highest irony that with all the yellow Catalin radios we now have, there were no radios made originally in yellow, with the sole exception of a gold Tom Thumb model made in 1938.

This has been a summary story of Catalin-type plastic radios – the details will be here at this web site over the next several years. They can also be seen in back issues of Radio Age and its predecessor, the MAARC Newsletter.


The Perils of Radio Shipping


The Perils of Radio Shipping

By Paul R. Farmer and Greg Gore

An earlier version of this article by Greg Gore originally appeared in Radio Daze, the Newsletter of the Carolina’s Chapter of the Antique Wireless Association (CC-AWA). Greg, WA1KBQ, resides in Charlotte, North Carolina, and collects National and Hallicrafters communications equipment. Paul Farmer is Membership Chair for the Mid-Atlantic Antique Radio Club. Paul, formerly K3YFQ, is a National equipment collector too, but also collects colorful plastic table sets from the mid-1930s to mid-1950s, and early transistor radios.

With the advent and explosive growth of Internet radio sales, the importance of safety in shipping is greater than ever for radio collectors. A scarce set badly damaged in shipping is a loss not just to the buyer, seller, or insurer; it is a loss to the entire collecting fraternity and to future radio collectors and historians. We have a responsibility to do our very best to protect and preserve the artifacts that we so strongly admire, for the appreciation and use of future generations.

When shipping radios and radio-related items, buyers and sellers should be particularly concerned about the way in which their precious cargo is going to be packed and shipped. Even though I always insure an expensive item, I never assume the insurer will pay—there are too many loopholes for the insurer and too many difficult hurdles for the insured. The best way to prevent a loss is for the buyer to ensure that the seller packs for an incredibly rough ride.

If you are the seller, pay strict attention to your buyer’s packing requests and err on the side of over-packing. If you are the buyer, good communications and rapport with your seller is your only real hope. If you have not clearly established these, do not close the deal. You should check your seller’s shipping safety record if you can (thanks, ebay), but this is not a substitute for precisely communicating your packing instructions to a sympathetic seller who wants, above all else, to please his courteous customers.

How fanatic should you be about packing vintage radio items? You just can’t overdo the packing part! Ed Gable, the curator of the AWA museum up in Bloomfield, New York, couldn’t believe it when I sent him a scarce and expensive pocket-sized Regency TR-1 transistor set (for loan in the museum’s recent transistor radio exhibit) in a 3 foot by 3 foot by 3 foot, double-walled, corrugated box with an inner box and six miles of large size bubble-wrap. But do you know what? It survived the trip without a scratch. And knowing how much I cared about packing, when the time came, he sent the set back with the exact same treatment! (The only exaggeration here is the length of the bubble-wrap.) More than once I’ve had a very large outer box punctured right down to, and even slightly into, a much smaller inner box (ouch!).

So how fanatic should you be about packing a prize? UPS doesn’t consider a package “mishandled” when it is subjected to a 3-foot drop, and they will tell you that even
6-foot drops are possible. Have you ever watched from your window seat as the conveyor loads shippers’ packages onto your aircraft? They don’t always stay on the conveyor. I’ve seen them drop to the tarmac, more than 15 feet below! And who knows how much weight or how many other packages may end up on top of your treasure in transit?

I know someone who used to work at UPS. When the UPS dock workers load the trucks, they are timed with a stopwatch. Asked if “FRAGILE” or “HANDLE WITH CARE” on the box helps, he said when he was there they didn’t have time to read what was written on boxes. When UPS delivers to our place, the driver tosses the boxes that are for us out the back of the truck onto the pavement. He is perhaps as careful as he can be given the situation—they are extremely busy. They handle a lot of packages every day and are accountable for their time. The boxes go out the back and hit the pavement. 

When sending something out, pack so that it can survive being thrown down a flight of stairs…all the way down a flight of stairs...a basement flight of stairs with a concrete floor at the bottom...without hitting any of the stairs! For something coming in, try to get the sender to wrap the item with many layers of medium or large-size bubble wrap, in two directions, and ask that he or she use a large, stable box, the stronger the better. Double-boxing should be an absolute requirement for all but the lightest and least valuable radios (transistor and ac-dc sets worth less than $75).

When packing, leave at least two inches all around between the inner and outer boxes, and two inches all around the bubble-wrapped radio, for fill. The fill material can be lots of densely crumpled newspaper or peanuts for those small, inexpensive items, but not for anything you care about. Peanuts and crumpled paper will loosen up and will not support the box shape during routine handling of heavy packages. Heavy items will attempt to move around and migrate to the bottom, where they will be vulnerable to cabinet damage from a drop. How many times have you opened up a package to discover that most of the styrofoam peanuts were on top of the radio rather than underneath where they are needed?

For heavier and more expensive items, use double-boxing with builder-grade styrofoam sheets tightly packed between the boxes for protection, rigidity, and support. Styrofoam sheets come in sizes up to 4 feet by 8 feet by about 1 inch thick. It is easy to cut to size with a utility knife or electric saw (band saw or sabre saw) and can be found inexpensively at Home Depot or Lowe’s. The inner box can have some styrofoam peanut fill to absorb shock, if it is very densely packed and if the set has many layers of large bubble-wrap, as described above. Scraps of bubble-wrap tightly packed in the inner-box fill area is probably better than peanuts. Bubble-wrap and peanuts have more give than styrofoam sheet. So use styrofoam sheet for rigidity and bubble-wrap and peanuts for shock absorption. I like to use all three together, in layers. Don’t leave any free space, whatever you do.

For a radio with a heavy chassis in a delicate wood or plastic cabinet, it is a very good idea to remove the chassis and ship the chassis and cabinet in separate boxes. Otherwise, when the radio is dropped upside down, the weight of the chassis may cause the cabinet to crack from the stress. But when the chassis is shipped separately, you may need to take extra precautions to protect IF transformers, coils, or other components that may be subjected to stress if the box is not maintained right side up. Each radio is different and there is no substitute for good judgment. Always, always, always remove the chassis from a catalin set and absolutely always double-box the catalin case, as described above.

Use extra padding on the front panel to prevent controls from jamming, bending, or breaking themselves or the front panel/case front. A lot of force can be transferred through packing material, and a high ratio of large set weight to the small knob surface can concentrate impact forces in the knob/shaft/front panel areas, if the box is dropped on that side. Heavy components mounted on the chassis may contribute to damage from a drop, as the force has to be absorbed by something. (A transformer in motion tends to stay in motion, even if the chassis it is attached to does not.) Missing rear cabinet screws for securing the chassis at the back (left out from a previous repair) can be another problem. There is no assurance of the package being shipped right-side-up. If a boat anchor is shipped with missing rear cabinet screws, you may get a bent or buckled front panel if the box is dropped and the radio happens to be upside down at the time.

If the set has expensive tubes, remove and wrap them separately or at least add packing material inside to prevent things from getting out of their mountings and banging around and making a mess inside. To prevent micro-scratches in plastic, painted, or lacquered surfaces, wrap the set first in tissue paper or soft, clean plastic, before the bubble-wrap goes on. Thin Glad-style food storage bags or soft plastic grocery bags work well for transistor radios and table sets. I’ve had some boat anchors with their original glossy painted surfaces in mint condition shipped to me, and I always asked for the set to be wrapped in tissue paper first. A couple of layers of soft tissue gives any stray dust some place to go instead of into the paint when the set comes under the transferred pressures of rough package handling. Remember, it is not possible to completely isolate the set from shock.

When you are having a radio shipped to you, if you are not confident that the sender understands or cares enough about all of this, offer to send him or her a proper box or boxes with packing material and instructions. I have done this more than once, and although it adds cost, it sure beats opening up a poor packing job and finding a damaged set, which I have also done more than once.

If you have to settle a claim with UPS, remember they are self-insured and will send out representatives to examine your item. They know what they are looking for and will be pretty critical of the packing and shipping materials. Unfortunately, most people pack and use materials that are below UPS standards for the delicacy, value, or weight of a particular item. The retail shipping stores you see in the strip shopping centers (Mailboxes, Etc. for example) usually do a horrible job unless you stand there and watch while they pack. Most of the time, you will get one thin layer of the small-size bubble-wrap and the rest will be peanuts, for which you will be overcharged on top of the UPS rates.

I recently read an account of how the radio manufacturers of the 1920s packed and crated their new merchandise for shipment. The story told of how they constantly tested their methods by throwing crated new radios out of a second-story window or down a flight of stairs and examining the results. They weren’t happy unless the merchandise made it OK. How can we expect our increasingly valuable and scarce vintage radios to survive all the perils of a bumpy trip and uncaring or even disgruntled package handlers, if the sets are just shoved in an old box with a little newspaper pushed in to take up space? Well, we can’t. But you know what to do.

MAARC History

MAARC History

A look back by Joe Koester

The Mid-Atlantic Antique radio Club celebrates its 10th birthday this month. Like the old cigarette commercial, we've come a long way, baby. It took a lot of hard work and effort to achieve what we have all done with this club, and we can be rightly proud of our efforts. We had no club, confederation, or group of radio collectors in the Baltimore-Washington area before 1984. I understand that a few people in northern Virginia tried to meet to create a club sometime before MAARC formed, but it never got off the ground. Prior to the formation of MAARC, some of us knew of a few others with similar interests, but we never managed to get more than one of two others together at a time.

Read more: MAARC History