German Glass Industry Report 21 on

German Glass Industry 104 After September 1945


  Target No.
Map Ref.
Name of Target A.G. der Gerresheimer Glashüttenwerke vorm. Ferd Heye.
Address Betriebsstätte Ettlingen in Baden
Date of Visit 22nd August, 1945
Products 1. Continuous glass yarns
2. Staple glass yarns
3. Glass Fibre thermal insulation.
Present Position This factory was a paper mill which was purchased by the Gerresheimer Company and is now being converted to a glass fibre producing unit. Production of Textile fibres started about 15th January, 1945. At the present time, the continuous fibre department is only partly in shape to operate (25%). No staple fibre is being made although the equipment appeared to be ready to operate at short notice provided enough platinum is available. The manufacture of thermal insulating glass wool cannot be started for several months since the re-arrangement of the buildings has only just started and the Military Government is not yet ready to allocate the needed fuel.
Plant 16 furnaces and winding drums for continuous fibre production 14 furnaces with blowers and perforated collecting drums and spinning devices for staple fibre production.
Key Personnel Herr Claus Siegfried, Manager (Oberingenieur und Betriebsführer.)
Herr Krannick, Plant Superintendent.
Employees At present

Estimated total for)
full operation )

(From Time-clock)

( Production



German Glass Industry 105 After September 1945

Description of Plant, processes, etc.

1. Continuous Fibre

This production unit when completed will consist of 16 forming machines; glass marbles melted and formed at the Company’s main plant at Gerresheimer-Düsseldorf are fed into small melting units made of platinum about 1/16" thick and about 8 cm. x 20 cm. x 12 cm. deep and tapered at the bottom so as to converge to about 2 cm. x 20 cm. in the centre of which are two rows each of fifty-one 1 mm. holes. At opposite ends of the rows of holes and oriented vertically are electrical control lugs about 2œ mm. x 4 mm. to which water cooled bus bar connections are made. A platinum - platinum rhodium thermo-couple is welded to the centre of one side of the metal furnace housing for control use. This metal is all enclosed in special sillimanite refractory shapes the outside of which is insulated with about 3 cm. of insulating cement. To operate this unit the current from a special transformer at 4 to 6 volts is fed into the water cooled lugs and this heats the platinum which in turn melts the glass fed in at the top. By control of the current flow, the temperature of the molten glass is held at such a point that it will flow through the holes but not drop off. To start the formation of fibre, a metal tool is pushed up into each hole and the fibre drawn out. An air blower is directed downwards along the fibre to assist the operation. When all holes have fibres hanging from them they are pulled together and passed over a cloth pad wetted with a binding mixture of benzene and plexigum from which the strand so formed is drawn on to a 25 mm. paper tube on a mandrel turning at 6,000 R.P.M. The fibre being drawn is traversed on to this tube by a rotating traveller device. 10 kilograms of fibre thus formed is produced in 8 hours. Current consumption is about 6 amps. at 440 volt. Samples of the marbles were taken.

2. Staple Fibre

This is to be made by 14 production units none of which are now in operation. Each unit consists of a platinum melting unit similar to the continuous forming device except for the fact that 28 holes, 0.7 mm. diameter are used and the fibres are formed by blowers rather than by mechanical drawing on a drum. This fibre falls on to a perforated drum 80 cm. in diameter and 40 cm. face width. This drum revolves slowly (about 60 R.P.M.) and is slightly evacuated internally. The fibre falls thus through a mist of emulsified mineral oil and is pulled off the drum through a revolving tube and over a traversing device on to a paper tube. 20 kilograms of fibre is thus formed in 24 hours. The blower is fed by steam at 250 lbs. pressure.

German Glass Industry 106 After September 1945

3. Thermal insulating wool

This will be made by the process already established at Gerresheimer

4. Fabrication

Conversion of the fibre made for textiles into yam is accomplished on standard twisting and plying machines. Multiple winding is also done on standard machines. The weaving operation is done at outside points; some fibre is sent to the associated plant at Hamburg-Bergedorf known as Deutsche Kap Asbest. (See Report XXV.

5. Applications of Products

(a) Continuous yarns are multiple wound at Ettlingen for wire covering.

(b) Continuous yarns are woven into cloths by contract and sale outright to others for use in many applications such as varnished electrical tapes, laminated plastic reinforcement, admixture with asbestos for increased yarnstrength and flame-proof curtains.

(c) Staple yarns are adaptable where thicker and more absorbent cloths are used. In Germany they are apparently used to a considerable, extent in combination with asbestos. Such yarns are used for acid filtration cloths. The yarns are also used where bulk is needed as a filler or where thermal insulation is needed.

(d) The glass wool to be made will follow the description and uses of that made previously at Gerresheim. The product will go into all kinds of thermal insulation, such as is used in buildings, pipe covering and the like.

(e) Fibre cloth can be impregnated with plastic and pressed to give a satisfactory mica substitute for electrical insulation purposes.

German Glass Industry 107 After September 1945


  Target No.
Map Ref.
Name of Target Glasfabrik Wittekind (branch of A.G. der Gerresheimer Glashuttenwerke vorm. Ferd Heye.)
Address Minden, (Westf.), Friedrich-Wilhelm Strasse, 105.
Date of Visit 8th August, 1945
Products Bottles in pale green and dark green, including demijohns and carboys. Wicker cases for larger bottles. Carboy stoppers (ground.)
Present Position The plant is ready to operate one furnace with a production of 18 tons per day when fuel is available. Estimated it would start in October. A second furnace was being rebuilt completely with new foundations. Raw materials in stock were estimated by the management to be sufficient for some four to six weeks run.
Key Personnel Herr Friedrich Jacobsen (Director)
Herr Walther Baumann (Works Manager)

(Herr Werner Kollmann from adjacent furniture Works acted as interpreter.)

Plant 1 tank furnace feeding four Roirant “B” and one Roirant demi-john machines (ready to work.) Capacity 18 tons per day.
1 tank furnace to feed seven Roirant “B” machines in course of erection (estimated ready in five months time.)
2 slat type lehrs, gas-fired, 3 m. broad, hand-fed from conveyor belts discharging into lehr front.
2 mixing m/cs (one as standby to the other);
one weighing m/c.
2 carboy stoppering spindles
1 bottom grinder (or mouth grinder.)
Employees Pre-war
(If one furnace operated need 220 men; if two Present 170 furnaces 320 men.)
German Glass Industry 108 After September 1945

Description of Plant, Processes, etc.

1. Tank Furnace

The one ready for operation had a melting end of 5.7 m. breadth x 5.2 m. length with a glass depth of 1.12 m. There were two throats in the bridge and the working end was semicircular with a short straight section joining to the bridge wall. The overall length of the tank was 9.7 m. One feature of the construction was the small size of the blocks used, namely 50 cm. thick x 43 cm. x 20 cm Another was the use of magnesite blocks 7 cm. thick as a lining on the bottom of the tank. It was stated that this worked well in protecting the tank bottom. A life of seven to eight years was claimed for the bottom whilst the top two or three courses of the walls lasted one to two years before needing renewal. The refractories were said to be made of Westerwalder clay (32% Al2O3.)

Revolving Pot A small revolving pot was provided in the centre of the working end to feed the demi-john m/c. It was approximately 80 cm. diameter.

2. Batch and Glass Compositions

These were given as follows:

Recently Formerly
Sand 170   SiO2 69.7   69.70  
Limestone 30   TiO2 0.15   0.15  
Dolomite 28   Al2O3 0.50   1.80 $
Soda Ash 38   Fe2O3 0.40   0.40  
Salt Cake 20   MnO 0.04   0.04  
Phonolite 15   CaO 11.2   12.0 $
      MgO 1.70   1.70  
      K2O 0.70   0.70  
      Na2O 14.7   12.60 $
      SO3 0.50   0.50  
        99.6   99.6  
        $ Modified recently
German Glass Industry 109 After September 1945

There was no laboratory control in the Works, samples being sent periodically (fortnightly) to the Gerresheim Works for analysis.

3. Forming Machines

These were standard and call for no comment.

4. Carboys

Stoppering A spindle (belt driven) carried a three jaw self-centering chuck in which the stopper was gripped. The carboy was slung from a frame work which had grooved wheels running on an overhead track so that the carboy was easily moved up to and away from the revolving stopper. Abrasive slurry was fed to the stopper in the usual way.

Blowing This was done by 12 blowers by “hand” methods, but it is believed that an automatic blowing process is to be introduced.

German Glass Industry 110 After September 1945


  Target No.
Map Ref.
Name of Target Glaswatte Gesellschaft m.b.H
Address Bergisch-Gladbach
Date of Visit 21st September, 1945
Products Glass Fibre (Centrifugal Process)
Bonded Fibre (Semi-rigid)
Insulating blankets and pipe lagging strip
Sectional pipe lagging (rigid)
Present Position Only partly working
Key Personnel Director: Herr John Gustav Campbill
Plant 20 machines with cullet melting furnaces supplying 1, 2 or 3 machines
2 compacting machines for sectional pipe insulation.
Employees For full production 300
Production at Full Capacity 6,000,000 Kg. per annum.

Description of plant, Processes, etc.










1. Centrifugal Machines

See Hamburg-Bergedorf (Oscar Gossler Glasgespinnst-Fabrik) Report XXIV.

The melting furnaces are essentially as in the Bergedorf plant but are built to supply 1, 2 or 3 machines.

2. Glass Composition

No fixed composition was stated. Cullet alone was melted, principally window glass with a little bottle glass added.

3. Products and Fabrication

Hand sewn blankets with paper and metallic mesh facing; sewn strip 3 - 6 in. wide for wrapping insulation.

German Glass Industry 111 After September 1945

Bonded wool produced by impregnation with starch on other binder. Sectional rigid pipe lagging. The latter was made by spreading loose fibre over a wire conveyor belt 10 ft. long x 3 ft. 4 in. wide. At the point where the belt turned over the roller at the discharge end there was located a second similar roller of 12 in. diameter, and a smaller roller of the diameter of the piping to be covered was placed to rest above these so that the wool could be guided under it and be wrapped around it by hand. Feeding waa allowed to continue until the desired thickness of covering was built up, whilst a moving spray gun applied binder as the wool was wound on. The assembly was then removed, dried in an oven and the glass layer cut off the former. Two machines handled the output of nine fibre producing machines working at the same time.

German Glass Industry 112 After September 1945


  Target No.
Map Ref.
Name of Target Oscar Gossler Glasgespinnst Fabrik G.m.b.H.
Address Bergedorf 1, Kampchausse 71 (near Hamburg)
Date of Visit 6th August, 1945
Products Drawn glass thread (drum wound) ) Raw
Glass wool by centrifugal process ) Products
Thermal insulation blankets, pipe laggings. Sound insulation cement for mixing with water to apply to walls to deaden echoes. Filters, tape, accumulator separators.
Present Position Plant running at about 10-20% of capacity (1 out of 6 m/cs on centrifugal process and 1 out of 12 on drawing process working at time of visit.) Short of labour and fuel.

The Company is associated with Deutsche Kap-Asbest-Werke G.m.b.H. at No. 9 in the same street (see Report XXV.) and is apparently a subsidiary of A.G. der Gerresheimer Glashuttenwerke vorm. Ferd Heye in Düsseldorf - Gerresheim.

Key Personnel Dr. Ing Wilhelm Esser (Director)
Herr Karl Arlt (Sales Manager)
Herr Heinrich Wett (Works Manager)
Herr Albert Bahn (Works Superintendent)
Plant 6 Centrifugal machines and furnaces to feed them.
12 Fibre drawing machines and furnaces to feed them.
2 Stitching machines in working order
1 Stitching machine in course of erection
2 Sewing machines for smaller jobs 1 baling press for loose baling of “centrifugal” fibre for storage in factory 1 baling press for smaller jobs
Output The production of raw glass fibres was quoted as:
(1) 42 Kg per m/c per 8 hr. shift for centrifugal process.
(2) 120-140 Kg. per m/c per 8 hr. shift for drawing process
German Glass Industry 113 After September 1945
  (3) The total maximum output of the plant was said to be approximately 300 tons per month.
Employees Pre-war

Description of Plant, Processes, etc.

1. Centrifugal Process

The Furnace This consisted of a firebrick structure approximately 30" wide by 54' long by 48" high fired by premixed town gas and air introduced at the top right hand side at the end nearer the centrifugal machine (as seen when looking from discharge end.) Each furnace consumes ca. 1,000 cu. m. gas per 24 hours. (5,500 cu. m. for the 6 furnaces.)

The Pots There were two in number set in cascade. In the first (about 34" long x 22" wide x 15" deep of egg-shaped section) cullet was melted to discharge from a lip at the narrow (front) end into the second which was about 30" long x 20" wide x 8" deep, also of egg-shaped section and with a discharge spout moulded in the nose to deliver a thin stream of glass to the centrifugal machine. The thickness of the walls of the pots was about 2" at the top and of the bottoms was 2œ-3". They were of Didier clay and were fired in the furnace.

The Batch The mixture melted consisted of bottle glass 4 parts, window glass 1 part, with optical glass (type not stated) when obtainable. Very little of the latter could be seen at the time of the visit.

The Centrifugal Machine This consisted of a vertical spindle driven at about 3,500 R.P.M. by a 4 H.P. motor. At the top end was fixed a horizontal refractory disc, 200 mm. diameter provided on the upper surface with about 300 radial grooves approximately 2 mm. deep. The glass stream fell on this and was thrown off as a fine fibre. A jet of air at 400 mm. W.G. from 3 slits in the casing surrounding the revolving disc blew the fibres through a funnel shaped opening in the casing directed towards a wire mesh cage on the factory floor in which it collected and from which it was periodically removed. Any “slugs” of glass not attenuated to fibre were thrown clear of the stream of fibres by their greater weight. A circular saw revolving in a vertical plane at 1,200 R.P.M. at the back of the casing, cut up the fibre into short lengths to facilitate removal by the blast. An emulsion of oil and water was sprayed into the casing to lubricate the fibres. (See Figure 4.)

German Glass Industry 114 After September 1945

2. Continuous Fibre Spinning Process

The Furnace This consisted of a central thin-walled cylindrical dish-like refractory receptacle, made by Didier and bought ready burnt, of 400 mm. diam. x 90 mm. deep x about 8 mm. thick, having some 240 circular apertures 4.6 mm. diam. in the bottom arranged in 4 concentric circles (see Drawing No. 5 which however shows 5 such circles.) This was fed with window glass cullet only from 3 horizontal refractory cylinders applied to the periphery so that 2 discharge holes in each registered with similar holes in the wall of the “dish” A feed hole through which the cullet was dropped by hand was located in the centre of each such cylinder at the top. The whole was mounted in a sheet metal casing and was packed around with a mixture of grog and plaster. The casing could be rotated in its bearing by means of a lever engaging ratchet teeth on the bottom of the casing to facilitate (a) feeding the cullet (b) reaching the “spinnarets” or discharge holes to draw off a fresh thread in the event of one breaking. Premixed towns gas and air were injected through a cover on top of the “dish” to give a temperature of 1,200° and the burnt gases escaped via the 6 side holea through the 3 feed holes in the horizontal cylinders. The refractory parts had a 7 days life on average. (See also Figures 5, 6 and 7.)

The Winding (Spinning) Drum This had a diameter of 1 m. and a length of about 1 m. Two were used with each furnace so that one could be running at 250 R.P.M. whilst the fibre was being removed in hanks from the second in the usual way.

Diameter of Product It was said that fibre down to 20 microns diam. could be made.

3. Making up Fibre into Fabricated Products

Insulating “blankets.” These were made by standard equipment by placing on a backing sheet (paper, asbestos, fabric etc.) a layer of fibre and then stitching the two together. As seen on the occasion of the visit paper was thinly covered with continuous fibre, then a thick layer of glass wool (centrifugal process) was laid on and covered with another thin layer of continuous fibre laid at right angles to the direction of stitching. The whole was then stitched together and cut into 3 m. lengths (1 m. wide) by means of a mechanically operated circular saw swung in an arc across the table. The “blanket” thickness was lœ"-2". A little was made with no backing material at all.

Special Shapes e.g. Boiler Insulation Asbestos fabric or asbestos-glass fabric jackets were stuffed with glass fibre and sewn up like cushions. Strong “eyes” were sewn to the fabric so that the cushions could be fixed to the object to be insulated. For some purposes aluminium foil (bright - very thin) was used top and bottom of the fibre.

German Glass Industry 115 After September 1945

Oscar Gossler Glasgespinnst
Fabrik G.m.b.H.


Figure 4 Centrifugal Fibre Process

German Glass Industry 116 After September 1945

Oscar Gossler Glasgespinnst
Fabrik G.m.b.H.


Figure 5 Continuous Fibre Spinning Process (I) perforated “saucer” in position. (Taken from vertically above.)

German Glass Industry 117 After September 1945

Oscar Gossler Glasgespinnst
Fabrik G.m.b.H.


Figure 6 Continuous Fibre Spinning Process (II).

Showing one of the three side chambers in position to register with holes in the “saucer.”

German Glass Industry 118 After September 1945

Oscar Gossler Glasgespinnst
Fabrik G.m.b.H.


Figure 7 Continuous Fibre Spinning Process (III)

Showing covering details in position. A mixture of refractory grit and powder is then rammed in to hold the parts firmly in the casing.

German Glass Industry 119 After September 1945


  Target No.
Map Ref.
Name of Target Deutsche Kap Asbest Werke G.m.b.H.
Address Bergedorf 1, Kampchaussee 9 (bel Hamburg.)
Date of Visit 8th August, 1945
Products Asbestos string, rope, cloth, gland packings, brake linings etc. Mixed fabrics (e. g. asbestos with wood cellulose fibre of glass fibre as "diluents", to save asbestos; up to 80% glass fibre was sometimes incorporated.) Firefighting suits were made from the firms products.
Present Position The factory was in full working order but full data concerning production was not obtained as the visit was only incidental to that paid to the associated firm of Oscar Gossler in the same street, which supplied glass fibre.
Plant Plant Spinning and weaving machinery of standard type (no inventory attempted.)
Key Personnel Dr.-Ing. Wilhelm Esser (Director)
Herr Ernst Wedekind (Asst. Manager)
Employees Pre-war


(1) The plant was visited in an attempt to follow up a rumour concerning the production of a special heat protecting glass said to have been developed by a Dr. Baier of Hamburg, after it was learned at the Oscar Gossler plant that Deutcshe Kap Asbest Werke G.m.b.H. made asbestos firefighting suits. It appeared however that usually the fire fighter wore separate heat protecting goggles of the Sekurit type made by the Jena firm of Schott & Genossen though some suits were made to take visors of some kind about which the firm professed ignorance.

(2) No claims were made that the use of glass fibre instead of asbestos gave a better product. It was stated that glass was purely a substitute material used because of the scarcity of asbestos in Germany.

German Glass Industry 120 After September 1945


  Target No.
Map Ref.
Name of Target Glaswolle Kommanditges. W. Schuller u. Co.
Address Coburg
Date of Visit 10th September, 1945
Products Glass fibre by drawing from rod
Present Position Not working, since the rod was previously obtained from factories in Czechoslovakia and Haselbach, Thuringia and supplies are now cut off.
Key Personnel General Manager Herr Werner Schuller
Furnaces, Plant, etc. 30 drawing machines each operating on 75 rods.
Electric Power (100,000 K.W.h. per month) or gas for heating.
Employees Pre-war
Subsidiary or Associated Companies Faser Industrie, Coburg (An administrative office for the French plant.)
Schuller & Co., Neues (Storage for 20 machines evacuated from the Russian zone.) Faser Industrie G.m.b.H., Mulhausen, Alsace (40 machines gas heating.)
Glasfabrik Wernerhütte, Haselbach, Thuringia (started during the war for U-boat thermal insulation; 20 machines now stored at Neues.)
R. Riedel, Unterpolaun, Sudetenland (a licensee allowed to operate one third the number of machines used by Schuller & Co.)

Description of Plant, Processes, etc.

1. General

The machines employed consisted of a heating furnace through which the rods were fed side by side, appropriately spaced, by passing between a pair of rubber-covered rollers whilst directed by guide eyes. Until the present time the heating was by gas flames but now

German Glass Industry 121 After September 1945
a heater has been developed comprising a pair of half-inch diameter electrical heating coils of resistance wire set in an insulating brick housing. The rods were fed to the space between the coils; the device, now being worked experimentally, was claimed to give better results than gas heating.

The fibres were pulled from the softened ends of the rods by a winding drum 1.2 m. diameter running at a surface speed of 2,400 m. per minute. The individual threads were kept separate from each other and guided on to the drum by sheet metal partitions. Lubricating oil on a flannel pad was applied to the fibre before winding. Winding was continued to give hanks, of approximately Ÿ inch diameter, which were cut off, bundled and sold.

Fibre Size Diameters of regular sizes were:-

No. Diam.
G.R. 30 15-18 microns
G.R. 18 9 microns (This was the standard product.)
G.R. 8 5 - 6 microns

2. Applications

Sales During the war 70% of the product went to Hardt u. Poconne, of Dahlhausen-Remschied (Map Ref. M54/U00) to make yarn as did 20% to Merkel and Kienlin of Esslingen (L49/S11.) The yarns were woven by other Companies e.g. Ruckert of Oberschonau. (There are 19 Schonaus in the G.S.G.S. 4346 gazetter; probably Map Ref. N51/K43.)

Possible Uses for Fibre Herr Schuller felt that glass fibre was not well suited for making, textiles. He considered there was a future for a loosely woven blanket material using Œ - œ in. diameter bundles of fibre to produce a material of appearance similar to the back of a cheap door mat. This would be in his opinion excellent for thermal insulation.