Casting Methods discussion

Discussions on various technical aspects of carillon instruments and standards.

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Casting Methods discussion

Postby JohnGouwens on Sun Dec 29, 2013 9:12 pm

More than nine years ago, I launched a discussion about the two basic methods of casting bells. The following excerpts are the meat of the responses I got, which sure were interesting!

October 7, 2004, I fired the first shot:

I have noticed with some interest that in addition to the tradition of bellfounders of certain countries to use a distinctive shape for the lip of their bells (English and French in particular are opposites in this respect), there is also a difference in casting methods between that used by the continental European founders and those in Great Britain. (So far as I can tell, Whitechapel and Taylor are relatively similar in this respect, and I do know that Gillett & Johnston was as well.) Since I have personally witnessed pourings at both Dutch foundries (and at Paccard, if memory serves correctly), and have visited Taylor and Paccard, and become familiar with what they do, I am really curious about why the tradition is different, and the relative merits of each approach. You will note that I decided to “liven this up” by making sure that representatives from the four major bellfoundries receive this message!

There are no doubt some details that are different, but Eijsbouts, Petit & Fritsen, and Paccard all build a “false bell,” usually out of a relatively sandy material with a waxed outer surface, upon the core (inner mold), which usually is shaped with some variation of a strickle (a shaping tool on a spindle). The decoration is applied, often using cast wax ornamentation, the entire “false bell” is finished in wax, and the outer mold (known as the “cope”) is then build up over the “false bell.” Once the molds have been properly formed, they are separated, the “false bell” broken up and removed, and the molds are reassembled in preparation for casting. (A bit of heat applied melts the wax, which facilitates removing the false bell, and leaves a nice, smooth surface inside the mold. If I have misrepresented anything, please let us know. (This invitation is extended particularly to the bellfounders.) My understanding of it is probably too simplistic, and I would appreciate being educated on the matter, as would others, I suspect.

Now, the English method also involves a core and a cope, but both are formed with strickles rotating on a spindle, one formed to the shape of each part of the mold. No false bell is used at all. Lettering and other decorations are stamped directly into the cope (in reverse, of course, so the lettering comes out correctly on the bell.) As I understand it, both Whitchapel and Taylor line the molds with graphite, which enables the bell to be removed fairly neatly from the molds when the casting is complete, and which gives the bells a bit of a “gunmetal” coloring when brand new. (The graphite eventually wears off, of course.) Whether G&J used graphite I really don’t know. (I would be interested in learning about that, actually.)

The act of pouring the bronze into the assembled molds is probably relatively similar at all of the bellfoundries. What interests me is why some use the “false bell” and some do not. I work with, know, and love examples of carillons made both ways (Ball State’s Paccard and of course Culver’s Gillett & Johnston in particular), and I would never buy the argument that either method produces inferior results, musically. I also want it understood that while I do have my own preferences for a favorite type of instrument, I greatly appreciate the best work of all of the major founders active today. I have had the pleasure of working with three of them on some level in a consulting capacity, and I follow with great interest the innovations all of them bring with their newest installations. I really am not “partisan” on this question at all.

I gather that from the standpoint of decoration, the “false bell” method has advantages, particularly in viewing the ornate bells that have come from many European foundries. (This comment would apply also to the musically very poor bells of Bollée at Notre Dame University and the Michiels bells at Saint Jean-Baptiste in Ottawa, Canada, which despite their sound are lovely to behold.) So, this leads me to some questions, which, I am hoping, might bring some lively, interesting responses. Here they are, and those who know real answers to this are invited to respond:

1. Which method (or is it even known) did the great founders of the baroque period use (Hemony, Witlockx, van den Gheyn, de Grave)?
2. Did the English founders always use the method they use today, or was that a development of the 19th century – or when? Who started it?
3. Have any founders tried the “other” method (the one they don’t normally use) to see if there were any advantages or disadvantages that would apply to them, or do they prefer to trust in their established methods and traditions (most likely believing them to be the “better way”)?
4. What thoughts or insights could the bellfounders share with us about making bells – not just this “false bell” question, but any other insights?

I recognize that some bellfounders may be inclined to keep a few “secrets,” though not as tightly-guarded as those of the Hemonys, so of course if some decline to respond, that should be respected. In advance, I ask the bellfounders to forgive any inaccuracies in my description of what they do. My main interest in this question is the difference between the way the English do it and the way the Dutch and French do it, and how it turned out that way.

Thoughts? Insights?

(Thought this might infuse a bit of life into the GCNA discussion list.)

- John Gouwens

Henk van Blooijs, from Petit & Fritsen, responded immediately:

Dear John,

We think that it might be good to pose your questions to Mr. Andre Lehr. I think he might be able to answer most of your questions.

Concerning your third question: there are many methods and many types of materials to be used. In the world of foundries, every year several new materials are brought to the market. We tried many things, but basically didn’t change much so far. Which is good doesn’t need change.

Enjoy the weekend

Kind regards

Henk van Blooijs
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Re: Casting Methods discussion

Postby JohnGouwens on Sun Dec 29, 2013 9:13 pm

The following is from Dr. André Lehr, posted with his permission:

DearJohn,
About the four questions I can give the following answer. There are four methods to model bells:
A. The false bell entirely of wax. This method was used till about the 12th century.

B. The false bell of loam covered with a thin layer of wax and on it the inscriptions and decorations in wax. Also the canons (crown on the bell) are in wax. This method is common in Europe till the present day. It was used by all bell founders of the past, for instance Hemony, Van den Gheyn etc.

In England this method was used till the beginning of the 20th century. See: H.B. Walters, "Church Bells of England" (London, 1912), p.36-45. On the end of his description of moulding a bell, he wrote: "The methods [with false bell] here described are now in some respects old-fashioned and various improvements have been adopted by modern founders."

Which method is used (strickle inside without false bell or strickle outside with false bell) can also be seen on the fineness of the inscriptions and especially on the decorations. This criterion confirms the caesura [change to a technique that does not use the false bell – Dr. Lehr clarified this more recently] in the beginning of the 20th century.

Outside of England there is no European bell founder who uses the English moulding technique. Moreover, they have never tried it. They don't do it because it is very difficult to make fine decorations. But in Tokyo I saw the English way of working by a Japanese bell founder!

best regards,
André Lehr
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Re: Casting Methods discussion

Postby JohnGouwens on Sun Dec 29, 2013 9:13 pm

The following response, from Andrew Higson, Bell-Master (casting department head) of John Taylor Bellfounders, is posted with his permission. – JG


John

I'm sorry not to have responded earlier - too busy making bells!

!. Which method (or is it even known) did the great founders of the baroque period use (Hemony, Witlockx, van den Gheyn, de Grave)?
AH: Pass

2. Did the English founders always use the method they use today, or was that a development of the 19th century – or when? Who started it?

AH: As far as I am aware and judging by the appearance of the vast majority of old bells that I have seen either here or in their respective towers, the loam and strickle technique seems to be standard in the UK. That includes bells that are reputed to be 11th and 12th century when the casting was undertaken at monastic foundations. From a purely practical viewpoint, as most of the bells cast for English towers were of a reasonable size, allowing the moulder to get inside the case to letter the bell, the concept of making a false bell would have seemed an unnecessary process. That begs the question - was lost wax casting on the continent common before carillons were developed? If the founder were suddenly required to make a lot of bells less than, say, 12" in diameter there would be a good deal of incentive to change techniques to allow him to put decoration on the little bells which he would then have extended to the larger bells.

3. Have any founders tried the “other” method (the one they don’t normally use) to see if there were any advantages or disadvantages that would apply to them, or do they prefer to trust in their established methods and traditions (most likely believing them to be the “better way”)?

AH: JT certainly dabbled with lost wax in the late 19th and early 2oth century - the bells at Lougborough parish church were lost wax castings as were the treble bells at Lincoln cathedral and a few others. Sadly, it was never pursued as anythig other that an oddity. As above, I think that as most of the bells we make are big enough to get into to put the inscription and decoration on and the finish isn't that bad, there wasn't much incentive to invest in the equipment needed. Consequently, almost all our little bells are plain, probably only having the date and badge on them. As far as I know G&J never tried lost wax. WBF (and JT) made a number of "Liberty Bells" using wax canons, but loamed bells. The bells we have cast recently with canons on we have used ceramic shells for the canons which give a better result even than lost wax.


Regards

Andrew
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Re: Casting Methods discussion

Postby JohnGouwens on Sun Dec 29, 2013 9:14 pm

Rick Watson (Meeks & Watson) sent along the following extensive response:

Thank you, Rick, for sharing from your knowledge and experience! – John Gouwens


Dear John:
John Widmann sent me a copy of your message sent to the GCNA list (apparently not the one I am on, as I didn’t get it directly, but did get your earlier messages and the replies concerning associate member voting and related matters). I do have some comments to contribute, and if you should want to copy any of them to other members, please feel free to do so. [Thus I am doing so here – JG]

One preliminary observation I would have is that I have found many carillonneurs who believe the use of loam molding, with the mold formed through the use of sweeps or strickle boards to be confined to bell founding; in fact, this has been a well known and widely used technique for making molds to cast a great variety of other things possessing rotational symmetry. Many foundries in this country once practiced this technique, at least upon occasion, which probably also explains why there were so many foundries who occasionally cast bells. Until comparatively recently, there was a great foundry engaged in loam molding at Milwaukee, owned by Allis-Chalmers. Loam molding was also used in making the huge bronze runners (turbine blades) for major hydroelectric installations, and the Allis-Chalmers foundry made many of these.

The matter of the adoption of the use of an outer iron shell or molding case to sweep the cope up in seems to have originated in the 19th century with Warner’s foundry in London. This is discussed in Trevor Jennings’s book Master of My Art, a very interesting history of the Taylor foundry. As I recall, he found some references in notes made at their foundry about some bells they said were "moulded Warner's way". I believe later on, they said that they had independently thought of this method of molding. Of course it is always somewhat difficult to determine just who may have been "first" in such matters, as several people often were working on the same problems at about the same time. You are quite right in pointing out these two important variations in the technique of loam molding: the original method still practiced, though with variations, by some of the continental founders, and what has come to be thought of as the English manner, still using a brick and loam core, built in that case on a cast iron plate, but using no false bell, instead sweeping the loam for the cope up directly inside the molding case or flask.

This English technique was eventually adopted by the four major founders of the late 19th-early 20th century in that country, Warner, Taylor, Whitechapel and Gillett & Johnston. (Side comment: I believe Warner’s never made a carillon, but they came close-- e.g. the 21 bell chime at Timothy Eaton Memorial Church, Toronto. As I recall, the largest bell is nearly as large as the bourdon of the G&J carillon at Metropolitan Church.)

You are no doubt aware that several of the earlier American founders, including both Meneely foundries and the McShane foundry, used a further
variation: rather than making a brick core on a metal plate as do the English founders cited, these Americans made use of a full two-part molding case or flask, having an iron core on which a loam coating was swept using a sweep or strickle board cut to the inner curve of the bell. Generally, both parts of the case were perforated to allow the escape of gasses. It also should be noted that it is possible to have a core that is too strong, which can be a cause of hot tearing of the metal as it cools and shrinks. The European and English brick cores tend to crush to a sufficient extent, I believe, to take care of what could be a problem; and the West Troy Meneelys described wrapping the iron core with straw rope prior to applying the loam to it, giving somewhere for the core loam to go as the bell shrank on cooling.

I really don’t know just who came up with the use of a full iron molding case first; it is possible it may have been Andrew Meneely. Perhaps Bill DeTurk or Carl Zimmerman may be able to shed some light on that point.
I do have in my personal collection a catalog issued by Andrew Meneely's Sons; it contains a description of their technique of molding using complete iron molding cases, and there is a woodcut of such a case alongside the description. The catalog is undated, but it must have been printed between
1851 and 1863, as this firm name was used only during that 12-year period.
This catalog was given me by the late Frank Johnson, and may have been given to him by Jim Corbett, who was a close friend of Alfred and Ernest Meneely.

I also am not sure if any of the other American founders made use of this method of the full iron molding case, but some may have done; again, Carl Zimmerman may be able to speak to that point.

There are minor variations in the European founder's use of the loam molding technique; two related ones that come to mind is the use of a steel outer flask or shell, and the use of a backing sand in this cope shell or flask to back up the loam; after coating the false bell to a thickness of perhaps 3/4" to 1" or so, the more recent practice is then to place the iron case around the mold under construction, and tamp in backing sand; sometimes this is cement-bonded sand, and some may use more modern chemical bonded sands for this.

A word might be said about the use of loam; many carillonneurs I have found do not know what this material is. In general, it is a mixture that is approximately half sand and half clay or clay and silt; there exist some natural loam sands that can be used as-is for such molding, or nearly as-is.
Often chopped straw or chopped horse-manure was used to obtain a mixture that was sufficiently porous to allow gasses generated in pouring to pass through it as the casting cools, instead of being trapped to form gas bubbles or holes in the casting. Loam mixtures in actual use for bell founding and general sorts of casting have varied widely over the years.

A more recent, and I think unique, variation of sweeping a mold up and using also a false bell is the technique described and shown in a video by Ole Christian Olsen Nauen at the World Congress a few years ago in Springfield.
He may perhaps have demonstrated this for visitors to this year’s World Congress. He has made some large bells by directly sweeping up a core, then a false bell and making the cope all without the use of loam at all, but instead using a modern chemically-bonded sand known as Alphaset, a trade name of the Borden Company.

Several founders today are making some or all of their bells using a permanent or semi-permanent false bell, or bell pattern. I have seen variations of this technique in use at two of the European foundries, but this was over twenty years ago (1983), so their present practice may differ.
At that time, one of these founders was using sand mixed with sodium silicate, and hardened in the mold by gassing with carbon dioxide; this is known generally as the CO2 process, and I believe may have originated in England for general foundry use. The other foundry was using a proprietary chemical bonding process to prepare the sand to use with permanent aluminum patterns. In our foundry, we use a process similar to the first, making use of a catalyst to harden a sodium silicate binder; this binds the sand grains with silica gel, and is a very environmentally friendly process, generating no unpleasant gasses when the molds are poured. We use steel cases to hold the sand molds for the larger sizes, and have some aluminum cases for the smallest bells.

I hope some of these observations may be of interest, and I would be interested to see some of the other responses you may receive or have already received. The history of various bell founding techniques is certainly of very great interest to me. [I am sending those earlier responses on to Rick directly. – JG]

Regards,
Rick.
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Re: Casting Methods discussion

Postby JohnGouwens on Sun Dec 29, 2013 9:15 pm

Gideon Bodden (Het Molenpad Expertise, The Netherlands) offered the following responses:



JG: I have noticed with some interest that in addition to the tradition of bellfounders of certain countries to use a distinctive shape for the lip of their bells (English and French in particular are opposites in this respect),
there is also a difference in casting methods between that used by the continental European founders and those in Great Britain. (So far as I can tell, Whitechapel and Taylor are relatively similar in this respect,
GB: No, Whitechapel and Taylor use different techniques. Whitechapel for instance does not burry the mold in the ground, Taylor does. In this respect Whitechapel does exactly what Eijsbouts does,

(JG, continued): and I do know that Gillett & Johnston was as well.) Since I have personally witnessed pourings at both Dutch foundries (and at Paccard, if memory serves correctly), and have visited Taylor and Paccard, and become familiar with what they do, I am really curious about why the tradition is different, and the relative merits of each approach. You will note that I decided to “liven this up” by making sure that representatives from the four major bellfoundries receive this message!
GB: one could say that the continental European founders basically use variations on ancient European bell casting methods. Eijsbouts has always tried to be a modern foundry, but despite little differences (for instance they shape the core by building in on a turning disk, not by a strickle turning around it) basics are just the same as all founders do. I believe the English founders in the 19th century took advantage from the great innovations the Industrial Revolution brought in that country in those years, and that is the reason their casting methods radically differ from the traditional European methods. Older English bells I believe were cast in a way very much similar to what the continental founders did. The Hemony’s by the way cast several bells for English customers (towns and wealthy churches).

JG: . . . . Now, the English method also involves a core and a cope, but both are formed with strickles rotating on a spindle, one formed to the shape of each part of the mold. No false bell is used at all. Lettering and other decorations are stamped directly into the cope (in reverse, of course, so the lettering comes out correctly on the bell.) As I understand it, both Whitchapel and Taylor line the molds with graphite, which enables the bell to be removed fairly neatly from the molds when the casting is complete, and which gives the bells a bit of a “gunmetal” coloring when brand new. (The graphite eventually wears off, of course.) Whether G&J used graphite I really don’t know. (I would be interested in learning about that, actually.)
GB: graphite has been used standard by very many European bell founders for centuries.


JG: The act of pouring the bronze into the assembled molds is probably relatively similar at all of the bellfoundries. What interests me is why some use the “false bell” and some do not. I work with, know, and love examples of carillons made both ways (Ball State’s Paccard and of course Culver’s Gillett & Johnston in particular), and I would never buy the argument that either method produces inferior results, musically. I also want it understood that while I do have my own preferences for a favorite type of instrument, I greatly appreciate the best work of all of the major founders active today. I have had the pleasure of working with three of them on some level in a consulting capacity, and I follow with great interest the innovations all of them bring with their newest installations. I really am not “partisan” on this question at all.
GB: Taylor used the false bell method for a short time, examples of those bells can be seen in their museum (wildly ornamented!) The false bell method allows for decoration as rich as anyone would want, and the direct molding does not. Also the construction of a crown on top of the bell is extremely difficult in direct molding. But as far as I know, the method of directly creating the mold leads to much stronger molds, and it is certain that such a mold behaves differently during casting and cooling. The results on the sound you know.

Shorter answers to the original questions:

JG: Which method (or is it evenknown) did the great founders of the baroque period use (Hemony, Witlockx,van den Gheyn, de Grave)?
GB: false bell.

JG: Did the English founders always use the method they use today, or was that a development of the 19thcentury – or when? Who started it?
GB: yes, I believe a 19th century change.

JG: Have any founders tried the“other” method (the one they don’t normally use) to seeif there were any advantages or disadvantages that would apply to them, ordo they prefer to trust in their established methods and traditions (mostlikely believing them to be the “better way”)?
GB: Taylor has worked with the false bell method. I don’t know anything about the other english founders. I have never heard of any continental founder experimenting with the English direct molding method. Eijsbouts, when requested by me in about 1993, refused to put any energy in this. They said it would require extensive study and experimenting before they would be able to cast with the direct molding principle. They said there are no customers asking for it. Nevertheless they continue to produce “replicas” of Taylor bells. (Philips Academy in Andover will be their next victim).

JG: What thoughts or insights couldthe bellfounders share with us about making bells – not just this“false bell” question, but any other insights?
GB: I do not expect one of the bellfounders you wrote is willing to answer.

(Note: Gideon later commented that he was impressed by the range of very interesting responses this discussion generated!)

The conversation seemed to die out after that, but of course, please feel free to add something!!
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Re: Casting Methods discussion

Postby CarlSZimmerman on Mon Dec 30, 2013 12:15 am

John's expectation that I could contribute to this discussion must be fulfilled! While I do not claim any expertise in the casting process, I have observed much in more than half a century of climbing towers, looking at old bells, and gathering information from various sources. So here, in no particular order, are a few notes on the subject.

The McShane Bell Foundry, Baltimore, Maryland, USA, used the separate case and core molding process, with loam (a special sand plus dried horse manure) as the molding material. At least, they were using this process during the last decades of actually casting bells, and possibly from their beginning in 1856. (They still have the cases and matching inside/outside strickles, though they haven't used them for years.) The argument for using this material was that it was both firm enough to withstand the pouring of molten metal and porous enough to let the casting gasses escape. They also managed the widely differing melting points of copper and tin in a way that I have not seen described elsewhere. They melted the copper and tin in separate vessels; when both were ready, they poured the molten copper into the molten tin, stirred them together using a green sapling, and immediately poured the mix into the bell molds. I must add that every McShane bell I have seen was an excellent casting, with a smooth finish, crisp lettering and ornamentation, and no evidence of porosity.

Sometimes, close examination of a bell will reveal evidence of how it must have been molded.

If the lettering has rough edges that look like wax residue turned into metal, it shows that the false bell method was used, and that whoever applied the cast wax letters to the false bell was a sloppy worker. This is unfortunately common on the bells of The Henry Stuckstede Bell Foundry Company, of Saint Louis, Missouri, USA. Sometimes one finds individual letters that drifted out of position as the cope was being built up over the false bell, or part of a letter is "bent" out of alignment. (Bells from the earlier phase of this foundry's history, carrying the name J. G. Stuckstede & Bro., almost never show these errors, indicating that much more care was taken in their molding.) Another bit of evidence for this molding practice is finding that the tops of letters have been knocked off by a sweep.

Evidence for the two-part molding method can also be found on bells. I've seen a school bell from the Fulton foundry (Pittsburgh, Pennsylvania, USA) in which an ornamental decoration on the waist of the bell was obviously double-stamped into the cope mold. (Incidentally, the Fulton foundry made more different shapes of bell than any other I know.) More subtle evidence for this method is lettering that is too shallow to have been made by the application of cast wax. Such lettering can be either rounded (as in the case of the second Stuckstede foundry of Saint Louis - Stuckstede & Bro., operated by the sons of J.G.Stuckstede) or square (as in the case of late bells from the Buckeye Bell Foundry, Cincinnati, Ohio, USA).

I specified "late" in the preceding sentence because the Buckeye Bell Foundry is one which I am reasonably confident changed their molding method at some point. This foundry was begun in 1837 by George Washington Coffin, and bells made during his management of the foundry are consistently the most highly decorated of any produced by any American bellfounder. The very high relief of the ornamentation on these bells convinces me that G.W.Coffin used the lost wax method. When the partnership of Vanduzen & Tift took over management of this foundry in 1866, the same method must still have been in use, as early V&T bells are as ornate as G.W.Coffin's work. But some time in the next quarter century, they must have shifted to the two part molding method, because late V&T bells, as well as all those made by The E.W.Vanduzen Company (successor to V&T) are of simple design with very shallow (albeit square-edged) lettering.

Much remains to be learned about the practices of other American bellfounders, but this gives you an idea of the variety of methods used in this country.
Carl Scott Zimmerman
Saint Louis, Missouri, USA - home of at least 36 bell foundries or bell sellers, 1821-1961.
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Re: Casting Methods discussion

Postby JohnGouwens on Mon Dec 30, 2013 1:02 am

Very interesting, Carl, thank you! (I think you responded back in 2004, but I lost track of that.) Do you really mean "lost wax" as in the entire model for the bell being made of wax throughout, or are you referring to bells cast with a false bell (built of sandy clay, with a thin coating of wax on its exterior)?
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Re: Casting Methods discussion

Postby CarlSZimmerman on Thu Feb 20, 2014 7:54 am

I doubt that it's possible to distinguish between the two types of false-bell method based on examination of the resulting bell. One would have to observe the molding process in operation, either directly or through historical documentation (photographic or written).
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