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Collectibles--General (Modern)/date range of Ohio Brass Silent Type insulators

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Question
Hi Bob,

Can you tell me the date range when Ohio Brass manufactured their Silent Type insulators?

Thanks!

Answer
I can't speak totally to the Silent Type brand name, but Radio treated insulators (designed to reduce AM radio interference) started with Ohio Brass in the mid 1930's with metallic top coatings.  Here is an article from the Crown Jewels on early OB radio treated pieces from 1937:

http://www.cjow.com/archive/article.php?month=1&a=01Porcelain%20Insulator%20News

They made radio treated styles marked S "OB logo" T starting in the 40's and I'm pretty sure they continued making these radio treated styles until the ceased production in 1987.  1950's were typically chocolate brown glaze with darker conductive glaze around the wire groove and inside the pin hole.  In the 1960's they transitioned to skyglaze (light blue-gray) with black wire groove and pinhole which is still used to the present by other makers.

         Hope this helps -- Thanks, --Bob

Collectibles--General (Modern)

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Bob Berry

Expertise

Questions related to collecting Glass Insulators and porcelain insulators - I can provide historical information as well as current collector values. I am also interested in purchasing insulators I need for my collection.

Experience

I have collected since the early 1970's and have much historical information, as well as knowledge of current insulator values.

Organizations
National Insulator Association (http://www.nia.org)

Education/Credentials
BS & MS in Electrical Engineering

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