Wooden Molds

[RED Matthews]

Well swizzle you asked for it, so here is a start on the subject. To all you bottle collectors and people in the know that can help us find out more on an old subject mold material.

Hello Jason. Well you have given me quite a job – and I realize that I have procrastinated on doing a complete blog on the subject of wooden molds. The reason for this is that I cannot find answers enough to satisfy the questions I generate in my head. For example, I know that the early wooden molds had to have been drilled on the parting face and held together in a positive vertical and horizontal location to make the seams of the cavity be held together properly.

I also have found out about a mold shop that still makes wooden molds for certain reproduction efforts; which doesn’t seem right to me that we need the copy the real thing. The only logic is to make money. Museums do it, Glass houses in different countries do it and it has been going on since the early American Flask bottles that people wanted to own and couldn’t find from the low quantities of the basic production made to hold a product. So it is all nothing new – just a fact of demand, calling for the products.

There are some wooden molds that I hope to examine this year at the Wheaton Museum in Millville NJ. I just haven’t been able to schedule a visit there yet. I have been there at least two dozen times when I was working with selling to glass industries all over a big part of the world. I have found that there are some at the Corning Museum and expect to be over there three of four times this summer.

I also know that I have two med bottles that were made in wooden molds. How I know; is, by the burned shoulder matches, giving the shoulder mold seam a different match of height, than one would see in a metal mold. There are other signs of seam deterioration because of this. I have two oval bottles that I feel were made in wooden molds and three demijohns that were made in wooden molds.

One of the demijohns had a plugged vent hole on the shoulder, that caused a big air trapped dimpled circle around the vent hole that is about: 2-1/2†inches in diameter. There is mold seam burn on both shoulder side seams. Another wood mold demi I have has a mold seam that goes from the neck down the side, across the bottom and up the other side to the shoulder. This demi is pictured in my home page blog – mainly because of the fold mark on the bottom which was created with a wooden tool to cool the glass bottom before it was set down on its bottom to apply the neck glass on and tooled for the tapered finish. This bottle has another bottle mystery that I can not resolve because the mold halves on one side seam has a 45º off set in the mold halves that is about an inch long and a good ¾†vertical difference, which had to be a method of vertical location of the mold halves. From this I have to assume that there was a dowel system on the other side mold parting face.

Another demi I have was made in a four part wooden mold. I also have some demi’s that have different blistered shoulders and glass surface differences that I feel were caused because of a different mold material having been used. What ? who knows? I know there were bisque fired clay molds used, but the books one reads, do not explain all the history of how early glass was made.

Also the job security of the early bottle makers was part of their job security if they didn’t tell others how the did everything. They only taught the members of their own shop team.

Well Jason asked me to get something started on Wooden Molds on the ABN FORUM, so here it is, for starters. My blog study is still in process. RED Matthews

 

[RED Matthews]

Hi again, This should have been the fourth paragraph in the dissertation above. I left it out some how.

When I was about seven years old I started hiking to my Uncles General Store in Logan, NY to visit and get some free candy or old fashioned barrel dill pickles for a snack. I also would visit and old Black Smith‘s Shop across the street. This mans work fascinated me no end. There was a wood lathe that had a big 5 ft. flywheel that turned the axels for wagons and the wheel hubs for wagons. It had a cross frame and a tool rest for his chisels. It also had a long wooden treadle that was hinges on the North wall of the shop and connected to the flywheel with a rod. He would turn the spindle flywheel and maintain its rotation by one foot on the treadle bar pumping the spindles rotation. I am sure that wooden bottle molds were turned the same way. REDM

 

[swizzle]

Ok, I think I may be a bit more confused about wooden molds. I always thought that they took 2 pieces of wood and hollowed them out in the shape they needed and then chiseled the needed words inside the hollows. I never thought about them actually turning the bottle molds on a lathe and then making bisque molds out of them. I'd love to see a series of video's on how the molds were made and how many different types of molds were used. I'm finding this all very fascinating. Thanx RED Matthews for starting this. I think it'll be a very cool thread. Swiz

 

[sandchip]

I guess you could mount the wooden blank on a faceplate, and turn out the insides, saw (rip) in half lengthwise, then turn a separate cup- or post-bottom piece.

 

[RED Matthews]

Back to you swiz, I didn't mean to say that the bisque molds had anything to do with the wooden molds. A bisque mold was made from a ceramic clay and fired to become a bisque (hard ceramic cavity). In the beginning of molding glass clay was used as a core and glass threads were wrapped around the clay and melted together. The clay inside had to be dug out of the vessel thus produced. A visit to the Corning Museum would let you see some of these developments of glass.

The wooden molds were made of fruit wood, like apple, cherry. I have read of them being made from iron wood, also. The objective of the fruit wood was to have a close wood without much grain in the wood. The soaked molds would absorb some of the
water and then, as the hot parison glass was blown against the wood there was a spacing action of steam generated which held the hot glass off of the woods surface. The wood surface would develop a chard surface that would then hold more water on the next mold use and actually do less damage to the mold because of the extra water in the molds surface. I have not seen a word about how many bottles could be made from these wooden molds, but I have been advised that the more modern reproduction molds get over a hundred marketable bottles. RED M..

 

[RED Matthews]

Now to you post, sandchip; I have been involved with all the machining of cast iron molds. This was my job in the Thatcher Glass Central Mold Shop. When I went there the parting face of a mold was being machined on ram type shapers. I made the smart a-- remark that was a question: "Don't you people know about milling machines? I had a chip on my shoulder because I was building a house for my mother next to our farm house. Twenty six weeks of unemployment money would have helped me get her house built.

As the manger took me through the shop I made several snotty remarks about their methods of doing things. I did get excited when I saw a Monarch engine lathe turning milk bottle molds - boring the square cavity with rounded corners. Any way when I got back to his office - he called his boss and said I am hiring this guy. I worked for them for 15 great years and learned a lot about a lot of glass making.

This description is regarding the process with cast iron molds for bottles:
The procedure was to machine the parting face and it had to include the locking devese of the two halves when fitted together. With a cast iron mold this was done on the shaper by leaving a raised tounge with 20º sides and then on the other half a matching groove with the fitting 20º female lock up. The pairs then had to be turned on the outside diameter of the mold halves by an operation called banding, which turned the outside diameter of the two mold halves. After that, the mold halves were placed in a pot-chuck and the face of a mold set-top was turned and the neck bored. The the pot chuck would be opened and the two mold halves would be placed back in it with the bottom end exposed for machining. The cavity was already cast in the mold half castings. The first thing to machine, was the cut out for letting the mold close around a bottom plate. Then a vertical sliding tool holder, set up with a boring bar and a template to lift and lower the vertical slide; would let the boring bar machine out the cavity of the mold up to the neck diameter. This often would take three or four paths of metal removal to clean up the cavity to the objective size.

The early molds had center bottom post on a plate base that the mold halves opened and closed on and controlled from a vertical pin the the hinge bosses. These molds I am telling you about above closed around a dovetailed ring around the bottom plate post.

I hope this helps explain the machining steps to get a glass mold ready to function.
RED M.

 

[RED Matthews]

Well I don't know what happened to the message I just wrote to you sand chip. It was a description of the machining steps of making a mold and bottom assembly. I don't have a clue as to where it went. I will have to check back and maybe even re write it for you. RED M.

Well this isn't needed now but I couldn't delete or Cancel it.

 

[swizzle]

Man what I wouldn't give for a time machine just to travel back and see how they made bottles and flask at the Mt. Vernon Glasshouse. What kind of molds do you think they used there? I know you said you did a bit of research on the Saratoga bottles. I scratch around up there from time to time and wonder how likely it would be to actually find one of the molds even if it was only half of one. Swiz

 

[RED Matthews]

Well swizzle, I am relatively sure that the molds were plain #3 mold iron with the type A graphite. The iron molds when they were junked would normally go back to the foundry to be remelted and cast into new molds. This practice is still used today for the scrapped molds in the industry. I know Dameron Alloy Foundries try to get all of their metal back from the glass that bought them.

When they started chilling the type A castings [approx 1863] against a cold half mold cavity chill set in the flask mold set-up, the chill created a type D graphite in the first half inch of the mold metal next to the chill. These chills had to be knocked out of the castings quickly, but the dendritic iron slowed the heat transfer speed and did away with the Cold Mold Ripple (generic whittle) in the glass.

Old molds are around and there was a post on the FORUM about some Coca-
Cola molds by someone I haven't been able to identify or find.
RED M.

 

[swizzle]

Is there any glasshouse relics that i might be able to find that would be of interest. I talked to one guy who was fortunate enough to find a blow pipe or two up there. I'd like to find anything of interest that had to do with the molding process in my old home town. Swiz