Another Brookfield CD 121 Blot out Question and Find

By Roger Poole; posted June 26, 2009

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Today I found this Brookfield CD 121 with blot outs on the rear skirt at an antique shop. Anyway, it is quite diffewrent then the other I asked about last week sometime. I didn't get no answer for that question. Maybe I'll do better this time. My first question is, does anyone recognize this piece? The skirt is slightly flared on the side down to the base. If you do recognize this piece maybe you'll have an idea what was blotted out on the reverse sid as well. This one has niether eight blots or five, the only two the price guide has a listing of. It also seems that the blotted area is too small for AM.TEL&TEL.CO to have been blotted out. However I do believe I can make out CO. at the end of the blotting. Anyone run across one of these? There is a backwards #10 on the top of the dome if that info will help. [id=250614829]

Till this date 8/1/16 I still haven't found matching molds. But the following is a conversation I had via Paul Greaves via email. You have to read from the bottom up. Pauls is first because he was replying to my questios. Enjoy!

I am not sure about the skirt thickness, but it is certainly possible that when doing re-work it became necessary to make new mold parts that formed the inner skirt, thus keeping the thickness correct. If not, the extra glass could add up to extra production cost and possibly out of spec insulators. (On the other hand, I have seen extra thick examples of certain insulators, maybe this is one reason why!)

As for dome profiles, yes I expect this is also related to re-work in this case.

Your last question is a good one! I wonder if they could be related to something else, like C D & P Tel Co. or something else? You might want to keep your eyes out for other Brookfield made CD 121s that might explain the 8-blotout specimens! Another candidate might include B. T. Co. of CAN. (they do look like Brookfield) or maybe even U.S.TEL.CO. ?


On 3/9/2015 12:15 PM, Roger Poole wrote: Paul,

Alright, I can see all you are saying know is possible. However I am know wondering how the thickness of the skirts were maintained? Would something else need to be changed on the part of the molds that form or press the inside of the skirts? The thickness of the skirts seem relatively the same regardless of where they are less or more angled. Lastly I notice a slight difference in the shape of the domes. My lesser angled pieces have a steeper slope as do all the AT&T pieces. All the more angled skirts have more an angle on the domes as well. Would you say the domes were reworked because of wear as well?

Lastly, the eight blot out pieces I have have totally different profiles then any other Brookfield five bots or AT&T CO. pieces. What would you say to that might be that would be?


On Mar 9, 2015, at 2:52 PM, Paul Greaves wrote:

Regarding the triple line... yes, that's what I was talking about. I am not sure how best to describe it (what is a good term?). In any case, it is caused by cutting a slot out of the mold right at the mold line, and replacing it with a new piece of metal. Hard to describe by email. As for the angled skirts... the purpose of re-working the molds is to refresh the surface and remove damaged areas. The areas that get the most damage seems to be at the sharp edges of the mold... this means along the mold lines (especially near the wire groove and right at the base) and around the base itself. By re-machining the area right at the base, this area can be renewed. Then smoothing the transition up to the areas of the skirt just above (speaking as you look at the finished insulator) leads to the angled skirt. The areas near the wire groove are typically repaired using the cut out and replacement method (leaving the triple line feature). I have seen some insulators that are noticeably wider at the mold line as compared to front-to-back (making them slightly oval). This can be caused by re-working the mold at the mold line without replacing any material.

As for why some molds would need more rework than others? It is possible some were made of better material than others. But it is also possible (probably?) that molds required multiple re-working stages over their lifetime. Midway in their life, perhaps light re-working was enough, then later they required more. So towards the end of their useful life, the skirts took on a more angled appearance.

Support for all this might require careful examination and looking for similarities across different profiles. For example, if you find two specimens with the blotouts in the same positions and perhaps the same dome number, where one is straight and one is angled, then I think we have good evidence they were from the same mold!


On 3/9/2015 10:59 AM, Roger Poole wrote: Hey Paul. Thanks for your knowledge. I do understand what you are saying. The AT&T piece or two I have really tight and fine mold lines and a couple look like a triple something or other. More like two flat areas next to the mold lines. All the straighter and all other Brookfield pieces seem to have the triple feature as well. How would you know that that would mean the molds were reworked? And how come more would be reworked with more an angle then others?

On Mar 9, 2015, at 1:38 PM, Paul Greaves wrote:

Hi, A mold that produced a straight skirt insulator could be re-worked to produce a more angled skirt one... if so, I would expect the angled one to be slightly wider at the bottom than the straight one. Also, do you know how to spot the signs of a worn or re-worked mold? New molds have very fine "tight" mold lines, older ones are more likely to have heavier mold lines or "triple lines" (like the "tin mold" EC&Ms). Sometimes the tripled sections are only in regions, like right at the base or wire groove. Also, often worn molds have "streaks" extending from some letters in the embossing, usually on one side more than the other. The classic example are the "speedy star" insulators that have a streak extending from the star going in one direction. You should be able to recognize reworked versions of the same mold by looking for details that are the same (dome numbers also might help), but keep in mind that embossing can be re-struck so it isn't always exactly the same. Hope this helps, -Paul Greaves