Painting by Immersion and by Compressed Air: A Practical Handbook

In Fig. 143 is shown very clearly the construction of the sprayer, which it will be understood comprises a combined melting and spraying jet and a feed mechanism. The metal, in the form of rod or wire, is fed to the melting flame. This, as already stated, is formed by coal gas burned in the air, or oxygen, water gas, acetylene, hydrogen, etc., may be employed instead of the coal gas. The gases are supplied at such a pressure as to prevent blowing out and to ensure a highly deoxidizing flame. The spraying jet can be of carbon dioxide, nitrogen, air, steam, etc., and it must be fed at such a pressure as to produce a sufficiently high velocity for successful coating. The usual gauges and reducing valves will, of course, be employed. The feeding of the wire is accomplished by a small pneumatic motor, driven by the spraying medium, either in series or parallel with the main jet. The dimensions of the wire nozzle, and feed mechanism vary with the different metals. To obtain a good adhesion between the metals being sprayed and the surface to which it is to be applied, the latter must be thoroughly clean and of an open nature, to give a key for the deposit. Sandblasting is sometimes employed to effect this.

Fig. 145 shows an enlargement of the nozzle with the different parts marked. The cost of the process is not prohibitive; the cost of the metal only on one square foot of a thickness of 0·001 inch is quite small with the cheaper metals. The process is put on the market by the British Metal Spray Co., Ltd., Queen Anne's Chambers, Tothill Street, Westminster, London, S.W.

In a paper read by Mr. R. K. Morcom before the Institute of Metals, the following interesting information was given:—

With a given design of jet there is only a certain volume left by the air-jet which can be filled with flame, and this flame has a limiting temperature which cannot be exceeded. The wire, passing through this cone of flame receives heat, partly by radiation, but chiefly by conduction, and becomes melted; but there is a definite limit to the amount of heat which can be picked up by the wire passing through the flame, and a definite limit to the rate at which it can be melted. This cannot be increased by forcing more gas into the flame, as the extra gas is merely blown away by the air-jet. It is possible to increase the rate of melting by shaping the nozzles so as to leave room for a larger cone of flame, and experiments are in progress on this point. There is, therefore, a most definite economical quantity of gas which should be used in the pistol, this quantity being about 1·5 cubic foot of hydrogen per minute, and 0·5 cubic foot of oxygen; or about 0·8 cubic foot of coal-gas to 0·65 cubic foot of oxygen for the present standard designs.

In refractory metals these quantities may be increased slightly, as a slightly higher temperature can be obtained if the burning gases are under a pressure greater than atmospheric, and this occurs if the gas quantities are increased, the inner surface of the air-jet acting to some extent as an enclosing wall to the flame. On the other hand, for the more easily fusible and oxidizable metals, such as tin, lead, and zinc, it is advisable to keep the gas quantities rather below the figure given, so as to avoid any possibility of overheating and burning any portion of the wire.

The outer jet performs a threefold purpose: it keeps the nozzles and wire cool, it cools the object, and it produces the requisite velocity.

The velocity of the air leaving the jet will be independent of the volume discharged, and depends only upon the pressure at the jet, so long as there is no disturbance due to the entraining of air from the surrounding atmosphere. This, of course, will actually occur in practice, and the layer of air must have a certain thickness in order to prevent its being broken up, and its velocity destroyed by mixing with the surrounding atmosphere.

As at present constructed the standard pistol uses about 0·55 to 0·6 cubic foot per minute for every 1 lb. per square inch air pressure, so that with an air supply at 80 lb. per square inch, which is a very suitable figure for ordinary spraying, the air consumption will be from 45 to 50 cubic feet per minute.

The bulk of this will be from 830 to 920 grammes, and the mass of metal sprayed by this air will be from about 8 grammes in the case of iron to about 200 grammes in the case of lead.

The action of deposition is probably a complex one. The minute particles of solid metal are driven with such force against the object that, in some cases, they fuse, but owing to their small relative size, are promptly chilled by the object to which they adhere. If any of the particles are molten or gaseous they will adhere. In addition, the suddenly chilled particles are possibly, or even probably, in the state of unstable equilibrium found in "Prince Rupert's Drops," and act like so many minute bombs, bursting on impact into almost molecular dimensions, and penetrating the smallest cracks and fissures of the object.

The process requires some care in manipulation, as, by varying the conditions, it is possible to spray porous or non-porous coatings, and, with some metals, anything from a pure metal to a pure oxide. With care, however, non-porous, oxide-free, adherent coatings can be produced, of almost any metal on almost any solid.

In addition to metals, it is possible to spray fusible non-metals, or, by stranded wires, alloys of metals or mixture of metals with non-metals.

The process is so new that its uses are still partly to be developed. But it is easy to see that it may have far-reaching value for protective coatings against weather or fire, for ornament, for electrical resistance and conductors, for the production of special alloys, for joint making, and for many other purposes.

Quite in a different category comes that of very fine casting. The surface of a pattern, polished or slightly greasy, is most minutely copied, and it is possible to produce process blocks very rapidly. It may be useful to line moulds before pouring in a metal. The application of the process to the production of very fine or coarse metallic powders is being investigated.

The bulk of the work has hitherto been carried on in laboratories, but the apparatus is gradually becoming used in the more progressive factories, where extended facilities, and the knowledge of specialised requirements, will ensure a rapid improvement in technique and results.

The research on the lower melting point metals has been greater than on the others, and undoubtedly the economy with them both can be greatly improved. Preheating of gases and air, supplementary flames acting in front of the main jet, and electrical methods of heating, are all still the subject of experiment.

The following metals are among those which have been successfully sprayed by this process:—Aluminium, brass, bronze, copper, cupro-nickel, iron, gold, nickel, silver, tin, zinc, lead.

It will be obvious that this method is a most useful one to employ when it is desired to prevent iron from rusting on machine parts which cannot possibly be treated by chemical or other anti-rust processes, and be rendered immune from rusting by treatment where they stand. To give some idea of the cost, it may be said that if the thickness of 0.001 of one inch of zinc is deposited, the cost of metal for coating 10 square feet would only be a fraction over 4d.; while for lead the cost would be about 2d. The amount of gas used is not a large item, being at the rate per minute of 0.50 cubic foot of oxygen and 0.55 cubic foot of coal gas when spraying zinc, and 0.101 cubic foot less in each case where lead is being used in the pistol. These figures are given on the authority of the "Daily Telegraph."

INDEX

• Accessories 121-133
• Advantages of Dipping 22
• Advantages of Dipping Piano Cases 46
• Aerograph 81
• Aerograph Air Pump and Tank Combined 118
• Aerograph Electric Motor Outfit 83
• Aerograph Spraying Cabinet 127
• Aerograph Turntable 134
• Aeron 85-87
• Agitating Apparatus 9-15
• Agricultural Implements, Dipping 58
• Air Drying Enamels 180
• Air-drying coloured Japans 157
• Air Heater 137
• Air Pump and Tank Combined 118
• Air Pump for Large Installation 119
• Air Transformer Set 93
• Airostyle 97
• Airostyle Air Compressor 115
• Airostyle Central Draught Fan 125
• Airostyle Plant 121
• Airostyle Plants for 16 Operators on Small Work 155
• Airostyle Plant Showing Ventilator 199
• Alabastine 29
• Apparatus for Dipping Piano Cases 42
• Application of Stoving Enamels 179
• Artistic Application of Paint Spraying 201
• Artists' Type of Invincible Sprayer 107
• Asbestine 73
• Auto Electric Air Heater 137, 139
• Auto Filter 93
• Automatic Control of Drying Room 68
• Automatic Electric Controller 111
• Automatic Finishing of Pianos 42
• Automobiles, Latest Method of Finishing 216
• Baird Machine Co. 249
• Baking Enamel 63
• Baking Heats, Safe for Pigment Colours 187
• Baking or Stoving, Hints on 180
• Barytes, Precipitated 70
• Baskets, Fancy 147
• Bean Spray Pump Co. 247
• Bearings, Paint Proof 13
• Bedsteads 33
• Bedsteads, Dipping 58
• Bedsteads, White Work 184
• Berkel and Parnall's Slicing Machine Co., Ltd. 167
• Bin for Spraying Light Articles 148
• Birmingham Small Arms Co. 147-164
• Black Japan Finishes 183
• Blinds for Paint Dipping Tank 10
• Block and Tackle 93
• Blooming of Varnish 68
• Blues 205
• Bone Black 70
• Bookbinding 146
• Brown, E. C. & Co. 246
• Brown Sprayer with Extension Rod, The 246
• Browns 207
• Bronzing 194
• Brush Graining 208
• Brushing versus Spraying 193
• Burnt Sienna 70
• Cabinets 127
• Cadby, G. & Sons 164
• Cans, Painting by Dipping 7
• Carriage Department, Woolwich Arsenal 54
• Carriages 146
• Carriers for Dipping Piano Cases 42
• Casements 7, 37
• Casements Dipping 60, 61, 65
• Casements, Steel 60
• Celluloid Buttons 3
• Celluloid Varnish, Recipe for 150
• Central Draught Fan 125
• Chicago White Lead and Oil Co. 188
• China Clay 73
• China Fruit Dish Decorated with the Airostyle 217
• Cleaning Metal Parts 41
• Coach Body Painting 55
• Coal Box, Metal Decoration done by Airostyle 241
• Coats of Paint, number 21
• Collapsible Gates 33
• Colour Glazing 202
• Colour on Bedsteads 33
• Colour Specimens, Spraying 153
• Colour Varnishes, Transparent 184
• Coloured Enamels 59
• Compressed Air, Painting by 78
• Compressed Air, Supply of 113
• Compressor for Airostyle Plant 165
• Concentric Form of Spray 79
• Construction of Airostyle 98
• Cost of Paint Dipping Plant 2
• Cover for Tank 11
• Crabs 18
• Crane Eureka 103
• Crane Record 104
• Crittall Manufacturing Co. 60
• Cycle Frames 197
• Cycle Parts 146
• Davis Gas Stove Co., Ltd. 161, 165
• Decorative Work, an Example of Sprayed 261
• Deed Boxes 38
• Demar Varnish 75
• Designs for Lamp Shades Done by Spraying 203
• De Vilbiss Air Compressor 115
• De Vilbiss Auto Cool Fan 125
• De Vilbiss Fumexer or Spraying Cabinet 131
• De Vilbiss Manufacturing Co. 85
• Diogrammatic Representation of Melting and Spraying
• Jets in Action 259
• Different Trades in Spraying, Requirements of 33, 141
• Dipping and Spraying Compared 197
• Dipping and Spraying Paints Compared 188
• Dipping Casements 61, 65
• Dipping Paints 7, 70, 72
• Dipping Process, Advantages of 22
• Dipping, Quantity of Paint Required for 77
• Dipping Sewing Machine Parts 34
• Dipping Tanks 57
• Dipping Troughs 238
• Dripping Platform 9
• Driving Gear for Tank 14
• Drying Room, Model 67
• Durability of Dipping Paints 1
• Dust, Excluding 64
• Electric Controller 111
• Electric Hoist for Heavy Goods 27
• Electric Motor Outfit 83
• Electrical Work 147
• Elevation of Spraying Plant 199
• Enamel, Stoving 63
• Enamelling, Slate 152
• Enamels 179
• Enamels, Air Drying 180
• Enamels for Steel Furniture 183
• Enamels, Heat Resisting and Slow Drying 180
• Enamels, Stoving 178
• Eureka Spraying Machine 103
• Evaporation of Turpentine 77
• Evolution of Spraying Apparatus 78
• Exhaust 113
• Exhaust Installation 122
• Fan, Central Draught 104, 124
• Fancy Baskets 147
• Files 38
• Filler for Iron 26
• Filler, Harland's 29
• Finishing of Pianos 42, 43
• Finishing Room 53
• Flash Point of Turpentine 76
• Fletcher, Russell & Co., Ltd. 167
• Floco Process 223
• Flowing-on System 25, 216
• Ford Motor Co., Ltd. 54, 59, 216
• Four Oaks Spraying Machine Co. 247
• Freight Car, Painting 250
• Frieze, a Sprayed 267
• Furniture, Metal 38
• Fumexer 86, 129, 135
• Gas Fires 197
• Gas Meter Co., Ltd. 172
• Gas Meters, Masks for 142
• Gas Meters, Spraying 148, 171
• Gas Light and Coke Co. 171, 181, 185, 191
• Gas Stoves and Ranges 149
• Gasometer, Painting 83
• Gates, Collapsible 33
• Gear Box, Paint Proof 13
• Gibbons, James 58
• Gittings, Hills and Boothby, Ltd. 168
• Glazing Colours 202, 205
• Gloss Paint 71
• Goodyear Stove, a Typical 237
• Golden Ochre 70
• Graining and Scumbling 208
• Graining Grounds 212
• Grays 207
• Greens 207
• Hanger, Iron 34, 38
• Hanging Apparatus 16
• Hard Wood, Primers for 74
• Hard Wood, White Dip for 75
• Harland, Wm. & Sons 29
• Harrison, McGregor & Co. 58
• Hart Patent Mask 143
• Hayward Bros. & Eckstein, Ltd. 60
• Heat of Drying Room 69
• Heat Resisting and Slow Drying Enamels 180
• Heavy Goods, Hoist for 27
• Henley's Telegraph Works, Ltd. 147
• Hickory Wheels 54
• Hints on Stoving or Baking 180
• Hoist for Heavy Goods 27
• Hoists 18
• Holden, Arthur & Co, Ltd. 167
• Holes in Woodwork, Stopping 29
• Hook for Suspending 17, 64
• Hot Air Method 235
• Illingworth on White Spirit 76
• Imitating Marbles 210
• Imitation Wood Effects 183
• Immersing Mangle Frames 35
• Immersion, Painting by 7, 11
• Implement Manufacturers 14
• Indian Red 70
• Introduction 1
• Invincible Sprayer 105
• Iron, Filler for 26
• Iron Hanger 38
• Iron Rods 34
• Iron Sashes 7
• Iron Window Frames 37
• Italian Raw Sienna 70
• Joist and Wheels Supplying Hanger 16
• Kerosene Oil 75
• Kettle Type of Spray 78
• Khaki Paint 57
• Kingsbury Manufacturing Co, Ltd. 168
• Lacquers for Spraying 80
• Lacquers, Paints, etc, for Spraying 177
• Lamp Shades, Designs done by Spraying 203
• Lime and Whitewash Sprayers 241
• Limewashing by Machine with 8ft. Bamboo Pole 245
• Limewhite Sprayer, Merryweathers 247
• Location of Work Cabinets 127
• Lockers 38
• Lowering Piano Cases into the Varnish Tank 47
• Lucas, John & Co. 188
• Lucas, Joseph, Ltd. 160, 169, 173, 175, 181
• Machine for Metal Spraying 256
• Making Stencils 144
• Mander Brothers 154
• Mangle Frames Immersing 35
• Marble Grounds 210
• Marshall Sons & Co, Ltd. 59
• Mask Hart Patent 143
• Masks and Stencils 141
• Masks for Gas Meters 142
• Masury, John W. & Son 189
• McLennan System 9
• Melting and Spraying Jets in Action 259
• Merryweather Limewhite Sprayer 247
• Metal Decoration 241
• Metal Furniture 38
• Metal Goods 38
• Metal Motor Parts 41
• Metal, Primers for 74
• Metal Sheets, Dipping 58
• Metal Sprayer, Details of 257
• Metal Spraying 255
• Metal Spraying Machine 256
• Metal, White Dipping for 75
• Midland Sprayer 108
• Model Drying Room 67
• Moller and Schumann Co. 180
• Morris, Herbert, Limited 21
• Morris Standard Electric Trolley Hoist 23
• Motor Bodies, The Floco System of Painting 224
• Motor Car Shops 231
• Motor Outfit for Spraying 83
• Motor Parts, Metal 41
• Motor Wheels 54
• Objections sometimes urged against Spraying 194
• Ochre 70
• Office Partitions 60
• Oil and Water Separator 111
• Oil in Dipping Paints 72
• Oxford Ochre 70
• Oven Baking Methods 232
• Overhead Rails 57
• Paasche Air Brush 109
• Paasche Automatic Electric Controller 111
• Paasche Motor Driven Fan 124
• Paasche Turn-Table 135
• Paint Dipping 7
• Paint Dipping Plant, Cost of 2
• Paint Dipping, Simple Form of 7
• Paint Dipping Tank 10
• Paint for Casements 37
• Paint for Metal Work 41
• Paint for Wagons 57
• Paint, Number of Coats 21
• Paint Proof Bearings 13
• Paint Sprayer, Portable 250
• Paint Spraying Apparatus Used by the Pennsylvania Railroad 252
• Paint Spraying, Artistic Application of 201
• Paint, Supply of 113, 122
• Paint Tank 8
• Painting a Freight Car 250
• Painting by Compressed Air 78
• Painting by Immersion 7, 11
• Painting Gasometer 83
• Painting Motor Bodies the Floco System of 224
• Painting Motor Wheels 54
• Paints Durability of 1
• Paint for Dipping 70
• Paints, Spreading Capacity of 77
• Part End Elevation of Plant for 12 Operators 159
• Pennsylvania Railroad Company 250
• Perkins System of Heating 235
• Phillips & Son 58
• Philorite 30
• Piano Cases, Lowering into the Varnish Tank 47
• Pianos, Finishing of 39
• Pickling Metal Parts 41
• Picture Frames 149
• Picture Mouldings 149
• Piece Work 145
• Pigment Colours, Safe Baking Heats for 187
• Pinchin Johnson's Drying Room 68
• Plants, Some Typical 54, 158
• Platform, Dipping 9
• Portable Paint Sprayer for Railing and other Work 250
• Precipitated Barytes 70
• Preparing Wood Before Painting 25
• Pressure in Spraying 80
• Primers and Surfacers 235
• Primers for Metal 71
• Primers for Soft Wood 74
• Protecting Parts not to be Painted 24
• Prussian Blue 70
• Purifying Air 114
• Quantity of Paint Required for Dipping 77
• Raido process 232
• Rails and Hanging Apparatus 16
• Rails for Overhead 57
• Railway Work, Portable Paint Sprayer for 250
• Raw Sienna 70
• Recipe for Celluloid Varnish 150
• Record Pistol 97, 99
• Reds 205
• Reducing Varnish 87
• Requirements of Special Trades 33, 141, 145
• Rims and Wheels 41
• Rods, Iron 34
• Rubbing Down 30
• Safe Baking Heats of Pigment Colours 187
• Scrubbing Air 114
• Scumbling and Colour Glazing 202
• Scumbling and Graining 208
• Second Coat Dipping Paints 74
• Sectional Drawing of Metal Spraying Machine 258
• Sewing Machine Parts, Dipping 34
• Shaded Effects produced by Spraying 213
• Shaded Work by the Aerograph 263
• Shafting for Tank 14
• Sheets Metal Dipping 38, 58
• Shellac Spraying 87
• Ships' Hulls Spraying 151
• Spraying Plant, Elevation of 199
• Spraying, Quantity of Paint Required 77
• Spraying Requirement of Different Trades 121
• Spraying Ships' Hulls 151
• Spraying versus Brushing 193
• Staircases 7
• Standard Hydraulic Immersion System 42
• Standard Varnish Co 42
• Steel Casements 60
• Steel Furniture Enamels 183
• Steel Implements 197
• Steel Office Partitions 60
• Steel Plate Fan 125
• Steel Sheets 1, 12
• Steel Wheels 41
• Steel Wool for Rubbing Down 30
• Stencils and Masks 141
• Stencils, Making 144
• Stirrers and Blinds for Paint Dipping Tank 10
• Stopping Holes in Woodwork 29
• Stove, a Typical Goodyear 237
• Stoving Blacks 179
• Show Card Done by Spraying 69, 209, 225, 239
• Shop Fronts 60
• Side Elevation of Plant for 12 Operators 158
• Skylights 60
• Slate Enamelling 152
• Sliding Doors 60
• Soft Wood, White Dip for 75
• Soft Woods, Primers for 74
• Spray, Concentric Form of 79
• Sprayed Decorative Work, An Example 261
• Spraying and Dipping Compared 197
• Spraying and Dipping Paints Compared 188
• Spraying Apparatus for Painting Freight Cars 252
• Spraying Apparatus, Types of 81
• Spraying Cabinets 127
• Spreading Capacity of Paints 77
• Spraying Colour Specimens 153
• Spraying Metal 255
• Spraying, Objections Sometimes Urged Against 194
• Spraying Plant, Cost of 2
• Stoving Enamel 63, 178
• Stoving or Baking, Hints on 180
• Stoving Temperatures 187
• Stoves, Notes on the Construction of 235
• Sub Frame for Tank 14
• Supply of Compressed Air 113
• Supply of Paint 122
• Suspending Hook 64
• Table Cover Decorated with the Airostyle 219
• Tank and Air Pump Combined 118
• Tanks for Dipping 57
• Tank for Dipping Metal Windows 63
• Tank for Painting Steel Sheets 12
• Tank Paint 8
• Tank, Special Form of 9
• Tank Used in Flowing on Paint 222
• Tapered Cans 7
• Temperatures for Stoving 187
• Test for White Spirit 76
• Three Tank Plant 15
• Thornley and Knight, Ltd. 157
• Time Saving 1
• Toys 1
• Trade, Requirements of Different 33
• Tramcars 154
• Transparent Colour Varnishes 184
• Trolley Hoist 19
• Troughs 41
• Tumbling Barrel Process 248, 249
• Turkey Umber 70
• Turn-Tables 129, 130, 134
• Turpentine, Flash Point of 76
• Type G Aeron 68
• Types of Spraying Apparatus 81
• Typical Hoist 19
• Typical Plants, Some 54, 158
• Ultra Airostyle 101
• Umber 70
• Varnish, Quantity Required for Piano Cases 46
• Varnishes for Spraying 80, 177
• Varnishes, Transparent Colour 184
• Venetian Red 70
• Ventilation of Paint Shop 67
• Ventilator for Plant 123
• Volume of Air in Spraying 80
• Wagons, Painting 54
• Wagons, Store Room 61
• Wells, A. C. & Co. 244
• Wheels, Rims of 41
• White Dipping for Meta 75
• White Paint for Dipping 71
• White Paste Primer 75
• "White Paints and Painting Materials" 72
• White Spirit 76
• White Work Bedsteads, etc. 33, 184
• Whitewash Sprayers 241
• Whitewashing Machines 78
• Whiting 73
• Wilkinson, Heywood and Clark 11
• Willys-Overland Automobile Factory 228
• Winch 18
• Window Frames, Iron 37
• Wood Effects, Imitation 183
• Woodwork Preparing before Painting 25
• Woodwork, Stopping Holes in 29
• Woolwich Arsenal, Carriage Department 54
• Woolwich Arsenal Store Room 61
• Work Cabinets 127
• Yellows 206
• Zinc Oxide 73
• Zinc Stencils 145