Bottle Molds

[Buffalo Hunter]

What was the average life expectancy of bottle molds? I'm beginning research for my next small project.

 

[RED Matthews]

Well Buffalo Hunter; I had to write to you to point out that there have been approximately 35 different metals used to make bottle molds through the last three thousand years. In addition to that, there are many types and formulas for just the cast iron molds.

I wrote a blog on the Chilling of the bottle cavity iron.in bottle molds. I asked a question about this process in a big Thatcher Glass meeting and every one thought I would be fired for asking such a question. When the V P of Manufacturing asked if any one had any questions: I raised my hand and asked: "Who, Where When and Why; did they start chilling the iron cavity of the bottle molds?" With over 200 people in the meeting - no one could answer my questions. It took me many years (35 ++) to find the answer. After I retired - I bought books and studied what I could find our about how bottles and other glass products; were made before 1900..

One of those books: written by Reha Mansfield Knittle titled "EARLY AMERICAN GLASS" answered all four points in my question. She touched on this subject in three major sections in her book.

I knew that it happened in the bottle industry from 1850 to 1860, by my studies and collecting of SARATOGA MINERAL WATER BOTTLES. I could tell by the disappearance of the cold mold ripple (whittle) in the glass. I know they never whittled in a cast iron mold with a jack knife - but a lot of early books called it that without knowing the difference.

I guess I should work up a blog on the mold materials used through the years and the characteristics they showed on the glass bottles. One time I got to make eight molds, each out of a different metal for a wine bottle so we could evaluate the glass surface effects. Interesting evaluation and it made me some private wine bottles besides.
RED Matthews
.

 

[Buffalo Hunter]

I'm curious for several reasons, but my interest would be those in the modern age 1870's thru 1930's.

 

[RED Matthews]

Hello again, Buffalo Hunter; In the time from you show most molds were made of::
Gray Cast Iron. All of these molds after 1870 would have had the molten iron poured against the cavity shaped cold cast iron bottle form.
Binney 51C was used and also would have been cast against a chilled cavity form.
Binney DV bronze was also used a lot for certain jars and milk bottles.
RED Matthews

 

[Buffalo Hunter]

That's very helpful, what was the life expectancy for a mold? 5-10-15 years?

 

[RED Matthews]

Well the life of molds varied through the years. There were many factors of the machine design, the pre-heating methods to heat up the mold equipment before it could be put on the machine. The types of swabbing brushes and mold release methods and maintenance changed constantly; Molds last for about three to four hundred thousand bottles today. Back in the early days of the I-S Machine they might have lasted for 50 thousand bottles per mold. I doubt that there was much recorded history on this type of question, but it all boiled to the mold cost when they priced out a bottle to produce. RED Matthews

 

[Buffalo Hunter]

Would it be accurate to believe that for a major client the bottle manufacturer used more than one mold simultaneously during production, even if this resulted in acceptable variations to meet quota according to contract?

 

[GuntherHess]

Would it be accurate to believe that for a major client the bottle manufacturer used more than one mold simultaneously during production, even if this resulted in acceptable variations to meet quota according to contract?

certainly, to do large production runs they needed many duplicates of the same molds.
"hand made" bottles are always going to have some variation from bottle to bottle. What was considered acceptible was a pretty loose definition. Blowers were typically paid peice wages so they wouldnt discard a bottle unless it was pretty bad (ie. didnt hold water[]).