Sentinel 284
This Sentinel 284 (nicknamed the "wavy grill" by collectors) has a cabinet made of catalin. These radios are very hard to find today or most often found with cracks. The reason catalin cracks is due to shrinkage. The dial glass on this radio is a reproduction. The original fell victim to the shrinking catalin syndrome....more on that phenomenon below.
Below is a definition of catalin taken from
www.maarc.org/Articles/Catalin_Corner/catalin_corner.htm).
"Catalin was a trade mark name of the cast phenolic made by The Catalin Corporation.....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".
• • • • • • •
What happens to catalin over time is that the water content eventually "out-gasses" and the cabinet slowly shrinks. Unfortunately, the metal chassis, screws and other metal parts don't. With that resistance the catalin cracks. Catalin also patinas with age due to a reaction to UV rays. What starts out as an alabaster cabinet eventually turns a butterscotch/yellow, blue becomes green etc. The underside of this Sentinel is bright yellow. Over the years it has patina'd to this nice rich butterscoth color.
The process for making catalin was much more time/labor intensive therefore fewer were made than regular bakelite. All of these factors have contributed to the rarity and desirability of catalin radios.
Made by The Sentinel Radio Corporation of Evanston, Illinois circa 1946-47.
Sentinel 284
This Sentinel 284 (nicknamed the "wavy grill" by collectors) has a cabinet made of catalin. These radios are very hard to find today or most often found with cracks. The reason catalin cracks is due to shrinkage. The dial glass on this radio is a reproduction. The original fell victim to the shrinking catalin syndrome....more on that phenomenon below.
Below is a definition of catalin taken from
www.maarc.org/Articles/Catalin_Corner/catalin_corner.htm).
"Catalin was a trade mark name of the cast phenolic made by The Catalin Corporation.....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".
• • • • • • •
What happens to catalin over time is that the water content eventually "out-gasses" and the cabinet slowly shrinks. Unfortunately, the metal chassis, screws and other metal parts don't. With that resistance the catalin cracks. Catalin also patinas with age due to a reaction to UV rays. What starts out as an alabaster cabinet eventually turns a butterscotch/yellow, blue becomes green etc. The underside of this Sentinel is bright yellow. Over the years it has patina'd to this nice rich butterscoth color.
The process for making catalin was much more time/labor intensive therefore fewer were made than regular bakelite. All of these factors have contributed to the rarity and desirability of catalin radios.
Made by The Sentinel Radio Corporation of Evanston, Illinois circa 1946-47.