[This article first appeared in 'Radio Age,' the monthly newsletter of the Mid-Atlantic Antique Radio Club.
It is reproduced here by permission of the author.  -- F.W.]

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During the late 1930s, three manufacturers of cast phenolic plastics, Fiberloid, Bakelite, and Catalin, competed against each other for the sometimes dubious honor of producing the most attractive radio cabinets. The Marblette Corporation struggled in the same business, producing cast phenolic jewelry, cutlery handles, umbrella handles, and other household items, and always bidding for the radio cabinet business. They succeeded in making only two radio cabinet castings, used in three Emerson models.   

On leafing through old issues of trade journals like Modern Plastics from, say, 1938 to 1946, a reader is struck by the colorful advertising by one or two manufacturers of urea plastics (Plaskon and Beetle) and three makers of cast phenolics (Catalin, Bakelite, and Marblette).  All these materials are what are termed thermosetting plastics, meaning that they do not significantly soften upon being heated. In this respect they are contrasted with thermoplastic materials, like polystyrene, PVC, and other modern plastics, which can be melted by the application of heat.  Thermosetting plastics like phenolics are harder, stronger, and more suitable for vintage radio cabinets than are the thermoplastics, owing to the heat dissipation expected to be present in the cabinet.

In those journals, ads placed by most thermosetting plastics manufacturers, like Durez, American Phenolic, and Bakelite, featured brown, black, or other dark-colored products, all made by compression-molding processes.  These products all begin with phenolic resin powder blended with coloring agents and fillers, also in powder form.  The big selling point stressed in advertisements of Bakelite or Durez compression-molded pot handles, for instance, would be the strength, comfortable grip, heat tolerance, and resistance to water, cooking residues, and the like.

On the other hand, ads featuring cast phenolic products were invariably in bright colors and stressed the beauty and gem-like qualities of the product, rarely mentioning the strength, hardness, or resistance to acids, oils, or other chemicals.  Yet many cast phenolic products were in use in the food processing industries, in the form of ball valves, tubing, mixing chambers, or paddles, and cast phenolic handles had been used for years on industrial and construction machinery controls.  Even in ads featuring cast phenolic billiard balls, it was the strikingly attractive color that was pushed, rather than the uniform density, strength, hardness, and elasticity which made these balls respond to the expert pool-shooter's sharp skills.

Of all the cast phenolic manufacturers, the Catalin Corporation probably engaged in the most ambitious fabricating adventures, pioneering the notion of multi-layer castings (where each layer is of a different color resin) for cutlery handles, stained-edge effects (to simulate stag-horn, for example), and the use of steel inserts to provide for voids in cast products.  To balance this little bit of innovative daring, the Catalin engineers conservatively reduced the number of coloring dyes in their inventory to twenty, convinced that all other dyestuffs available were unstable in the harsh environment present as the product is cured in the ovens.  Catalin was rewarded by securing the contracts to build cabinets for essentially all Fada and Garod cast phenolic radios, as well as several others, like the GE L570 and all RCA Catalins except the Little Nipper 11. One color that Catalin never advertised strongly was yellow, so that their Tom Thumb radio cabinets in "virgin gold" were the only yellow radios made.  Their engineers were never convinced that yellows could be made stable enough to withstand the effects of ultraviolet radiation.

By way of contrast, the Bakelite Corporation claimed, in their trade journal ads, that their Bakelite Cast Resin could be made in "thousands of colors," but they were not adventuresome in the variety of shapes they were willing to tackle.  In fact, Bakelite's choice of colorants for their cast phenolic was identical to Catalin's -- they simply had more shades advertised, and they achieved the variations simply through adjustments in color saturation.   Nevertheless, when RCA's Little Nipper Division went to Bakelite with the order for Little Nipper 11 cabinets, only two colors were produced, Brazilian (greenish) Onyx and Arizona (Ivory) Cream Onyx.  Each of these colors required a nearly clear resin mix, as well, used as a mottle (or swirl).

But a radio company that built some of the most interesting radios in cast phenolic cabinets was Emerson.  This company shunned the "big guys" in the cast phenolic business, always trying to get a bit more for the money by working with "also ran" plastics outfits.  For their first cast phenolic radios, the 1937 Models AU-190 and AX-235, Emerson gradually came to understand that it wasn't the basic plastics manufacturer that was the cost driver in radio cabinet production, but the plastics finishing company, especially if the cabinets were to be more than plain flat-faced boxes.  Emerson talked to Catalin about the AU-190 in early 1937, but then awarded the contract to Fiberloid Corporation, a smaller cast phenolics maker who offered a sweeter sounding deal. Both Catalin and Fiberloid (the latter staffed by former Catalin employees) relied on Plastic Turning Company, Leominster, Mass., for the finish work, and here Catalin got the better prices, owing to their larger volume of plastics production and finishing.  Thus the amount Emerson actually saved by going with Fiberloid was essentially nil.

Fiberloid's cast phenolic plastics had color limitations similar to Catalin's.  This is not surprising, since Fiberloid employed ex-Catalin chemists and engineers.  The first runs of AU-190 cabinets were produced in the usual Catalin-type colors: lapis lazuli (mottled blue), mottled red, alabaster, onyx, and a mottled walnut.

Almost immediately after production of the cabinets got established at Fiberloid (and the cabinet finishing, at Plastic Turning Company), the Fiberloid outfit went belly-up, primarily because the bulk of cast phenolic sales, for toiletries, buttons, and kitchenware, was going to Catalin.  But there was some bad blood between Catalin and Fiberloid, so Catalin did not run to the rescue of their competitor as he bobbed to the surface for the third time.  Instead, Monsanto stepped in, and managed the company for the rest of the initial production of AU-190 Emerson cathedrals.  When it came time for the production of the later BT-245 cathedral, Emerson got their hands on the steel arbor used to make the AU-190 lead molds, giving Emerson the privilege of selecting any cast phenolics company to finish the AU-190 and follow-on BT-245 production.  Monsanto, the new owner of Fiberloid, had a Lexus mentality, and did not believe in haggling, so Emerson broke off with them, and took the order, and the arbor, to the Marblette Corporation, another "also-ran" in the cast phenolic business, who was struggling to keep up with Catalin, at least in the advertising field.  Marblette ads often boasted "thousands of colors," probably actually meaning that there were thousands of shades of some 20 colors. 

Marblette proceeded to make BT-245 cabinets, throwing in some AU-190 cabinets (probably needed as dealer replacements) as well.   Of course, to Marblette, these were the same cabinet; it was up to Plastic Turning Company to make the difference.  The BT-245 was heavily ground down on the front surface, with only general rounding of the front comers.  The AU-190 had a stepped thickness front, with the center section thicker, embracing the speaker slots, with more gently rounded front corners.  The BT-245 would get cellulose acetate louvers and knobs, while the AU-190 would sport cast phenolic knobs and a special grille-cloth.   Marblette experimented with some strange colors during these production runs. They increased (maybe by accident) the violet content of lapis lazuli, coming up with deeper blues than ever before at Fiberloid or Monsanto.  Their mottled red, in some batches, was too thoroughly mixed, producing a non-mottled light tomato red.

Emerson was pleased with Marblette's efforts, and gave that company their order (and the steel arbor) for the BM-257, nowadays called the "Big Miracle."  Both the AU-190/BT-245 arbor and that for the BM-257 were made for Fiberloid by LeCour, a machining works I believe to have been in Minneapolis.  These arbors have extremely low "draw relief," or thickness taper, meaning that the cabinet wall thickness is not remarkably different from the front to the rear of the cabinet.  Not only does this make removal of the arbor from the lead mold difficult, but it makes removal of the cured cabinet from the lead mold equally hard.

Plastic Turning Company, who did the initial-run finish (machining and polishing) work on these cabinets, liked to get them from the casting company (Fiberlon, Monsanto, or Marblette) slightly undercured, such that the phenolic was a tad soft and easy to machine.  They returned the partially finished (machined but not yet polished) cabinets to an oven for eight more hours of curing before final polishing of the rock-hard cast phenolic.  The final 1938 runs in all three radios, AU-190 replacement cabinets, BT-245 cabinets, and BM-257 cabinets, were completely manufactured at Marblette, including machining and polishing. This move away from Plastic Turning as a subcontractor was a cost-cutting effort, but it further aggravated the competitive hard feelings between Catalin Corporation, who stuck with Plastic Turning and Marblette.

And true to Marblette's advertising, these two Emerson radio cabinets (three, if you consider the AU-190 to be separate from the BT-245) are found in more different colors than any radio in true Catalin.  It is not certain that all these colors were intentional; they might have resulted simply from poor process control at Marblette.  The only other radio cabinet found in more different colors might be the international Clockette, which was also initially made by Fiberloid.  It is entirely possible that the Clockette cabinets produced after the initial production, such as those made for dealer-replacement purposes, were also made by Marblette.  Such a turn of events would not be surprising, as Marblette often resorted to "picking up the crumbs."

But the only cabinets known for certain to have been made by Marblette were the Emersons: the two tombstones and the 'Big Miracle."   Despite this failure to secure a fair proportion of the radio business, Marblette went on to survive the 1950s, on the way, buying the Catalin Corporation assets upon their 1953 failure and struggling for twenty more years, before finally going on the auction block in 1973.  During those twenty years, Marblette made a few clock cabinets, barometer housings, and radio cabinets using lead molds made from dipping arbors of the old Catalin and Fiberloid Corporations.  Fig. 2 shows one of these, a lapis lazuli (mottled blue) Emerson tombstone "in the rough," with the front face unfinished.   Here's an opportunity for someone with considerable skill and patience to make either an AU-190 or BT-245 in blue, depending on which chassis that person has.

The AU-190 (or BT-245) cabinets that Marblette workers tried to make in the early 1970s all had full bottoms, without the cooling cutout that is usually found in that radio.  The arbor has no such cutout, and it is apparent that a steel filler was used to create the void in the bottom of most AU-190 cabinets.  The later "Big Miracle" arbor does have the cutout as a permanent part of the arbor, making the manual placement of a filler unnecessary.   Plastic Turning also had a punch press which could cut out the needed bottom vent if the cabinet blank supplied from Fiberloid or Marblette was undercured and a bit leathery.  The lead molds found in the Marblette factory residue had been poorly stored, and were jammed with dirt and sand, leaving them unsuitable for use as radio cabinet molds.

Notice the series of pins or posts surrounding the cabinet, proper, in the arbor in Fig. 2, and the resulting holes in the lead mold in Fig. 3.  I wondered what these were for, until I realized that they facilitated the spreading of the lead mold for removal from the cured cabinet.  Marblette workers in the 70s apparently didn't realize this, so they damaged every AU-190 cabinet found in the junk pile of Marblette through their heavy-handed use of air hammers.

Biographical note.  The author was born in 1931and has been researching old radios for the past 50 years.  He is president of the Mid-Atlantic Antique Radio Club (MAARC) and has written about 250 articles for MAARC's newsletter, Radio Age.
Click here to send Ed e-mail.

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