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Collectibles--General (Modern)/Dominion - 42 cd 155 red black?


Dominion insulator -42
Dominion insulator -42  
diamond D 59 2
diamond D 59 2  
QUESTION: Hello Bob,

We just found that insulator...what could you tell us about it's value or where i could find more informations.

Thank you in advance


ANSWER: I strongly suspect that this insulator has been irradiated to turn a clear insulator to dark brown.  With both bottles and insulators some questionable dealers will expose the glass to a radiation source (cobalt 60 or the like) - typically used in fruit/vegetable sanitation.  This turns common colors to new shades -- brown and purple are the most common.  This style (we identify this as CD 155) is not known in brown, and is most typically found in clear glass.  Extended exposure to the sun or heat will sometimes fade the treatment (a good test but can take up to a year to see results).  It is also possible that someone coated the insulator with glass stains - this should be easy to detect with a sharp knife or acetone -- given the color I think radiation is more likely.  Here is a link to a good article on altered colors:

If you can get a light to pass through so I can check the true color (too dark in the photos) I could double confirm.

         Thanks, --Bob  

---------- FOLLOW-UP ----------

QUESTION: Thank you for your fast reply,really appreciated

Here others pictures with some better lighting,hope it helps

ANSWER: Thanks that helps -- The color is right for irradiation but a bit darker than usual.  This style is not known naturally in amber so I suspect this has been altered.  Was this found in Canada (Dominion is a Canadian maker) but they do show in the US from time to time.


---------- FOLLOW-UP ----------

QUESTION: Thank you Bob

Yes in Canada

we bought it from a old lady in a garage sale near Montréal,Qc.

I just found a interesting article on Dominion glass company by Steeve Goodell

"CD 154 and CD 155, No. 42 was first produced on February 6, 1927, and was still being produced in August 1959. Earlier No. 42 insulators were of CD 154 design, and then at an unrecorded date changed to the CD 155 design. The only difference between the two is an added glass reinforcement to the wire groove. This is the most beautiful of the Dominion glass insulators. The colours include:

clear, light green, light straw, light sage green, dark straw, pink, honey amber, dark red amber, yellow amber, light yellow amber, light yellow, light cornflower blue, cornflower blue and dark cornflower blue. The value of these pieces range from $1 for a clear one to $400 for a dark cornflower blue piece.

Thank again for your help

Thanks --

Yes the 154 style was earlier and comes in some great colors!  Here is a link to some examples.

When the style was upgraded to the 155 the production was clear glass or close.  I have never seen an amber Dominion 155, and there is no listing in our price guide.

         Thanks, --Bob

Collectibles--General (Modern)

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Bob Berry


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.


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

National Insulator Association (

BS & MS in Electrical Engineering

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