US3523542A

US3523542A - Hair curling and straightening means including an electrical resistance heating surface film

Info

Publication number: US3523542A
Application number: US711416A
Authority: US
Inventors: Paul Eisler
Original assignee: Individual
Current assignee: Individual
Priority date: 1968-03-07
Filing date: 1968-03-07
Publication date: 1970-08-11
Anticipated expiration: 1987-08-11

Description

United States Patent [56] References Cited UNITED STATES PATENTS 8/1897 Rhodes.........................

Paul Eisler [72] Inventor 56 Exeler Road, London NW. 2, England 711,416

589,397 2,500,554 3/1950 MacDonaldetaL.

21 AppLNo. 221 Filed Mar.7,l968

Patented Aug. 11 Weitzner...................... continuation-in-part of Primary Examiner F. Barry Shay Ser. No. 293,953, filed Assistant Examiner- Jay N. Eskovitz July 10, 1963, which Attorney-Watson, Cole, Grindle and Watson is a continuation-in-part of Ser. No. 783,609, filed Dec. 29, 1958.

[54] AllSTRACT: 1n the curling or straightening of hair an electric HEATING SURFACE FILM res stance heating surface iilm operating at low voltage and 13 Claims 24 Drawin Fi 5 giving umform surface heating 18 used with a support such as a 8 g roller and clamping means for the hair, the structure having [52] 11.8. 132/33, perforations to permit the escape of fluid e.g. having matched lined with the film. A metal comb or brush has the film on the back. A tape cable meshes. A straightener has flat spring jaws 219/222, carries the supply and a set of curlers can be unplugged as a set from a variable transformer.

[501 FieldofSearch............................................

223, 224, 225, 226; 132/33; 34/1 (Misc) o. QQQQQ WQ H MQ MMH o o o o o o Patented Aug. 11, 1970 I Sheet INIVENTOR Patented Aug. 11, 1970 Sheet INVENTOR Pa uZ 5L5 Z61 wit; TTORNEYJ Patented Aug. 11, 1970 Sheet Fag Z Patenfed Aug. 11, 1910 3,523,542

INVENT R P5112 ELS er 4 Patented Augyll, 1970 3,523,542

Sheet 5 015 l N VENTOR Pd L /Z 5/5262 IIAIR CURLING AND STRAIGIITENING MEANS INCLUDING AN ELECTRICAL RESISTANCE HEATING SURFACE FILM This invention is a continuation-in-part of my application Serial N0. 293,953 filed my" I0, 1963 for Dryi ng Method and Means (now matured into Patent No. 3,372,487) which was itself a continuation-in-part of my application Ser. No. 783,609 filed December 29,1958 for Electric Foil Resistance Drier (now matured into Patent No. 3,099,540).

The invention relates to electric heating under conditions in which particular advantage can be taken of the characteristics of electric resistance heating films, that is to say heating elements comprising an'electric'ally' conductive surface pattern distributed over it. The film could be a thin layer of insulating material such as paper covered with a conductive coating of carbon or graphite particles to which connection is made by low resistance metallic foil busbars or terminals (see for example FIGURE l l of my Patent No. 3,033,970 and FIGURES 46 to 48 of my Patent No. 3,296,415) but preferably it is a patterned metallic foil as described in my Patents No. 3,033,970, No. 2,971,073, No. 3,020,378 and especially No. 3,283,284. Such films need not consist of more than the foil pattern itself but usually the foil will be coated or covered on one or both sides with insulation, e.g. lacquer or thin paper.

Such heating films can readily be made with a pattern which represents a substantially uniform surface loading and therefore substantially uniform development of heat over the surface area. ln particular cases the loading can be made different in different parts of the surface. They can be made thin and flexible and by crimping the foil madereadily deformable in their own plane as 'well as perpendicular thereto so that they can be disposed close to intrinsically curved surfaces. Their thinness gives them very low thermal inertia so that their temperature can be rapidly and accurately controlled. They are readily made so that they can be operated under voltages which are safe for human contact generally at a voltage below 50 and preferably considerably below 50, say 12, 6 or even lower. They are also cheap to make, using aluminium foil for the conductive pattern. The current used will generally be in the range of amperes while the resistance of the pattern will be in the range of ohms as distinct from milli-ohms or kilo-ohms. Desirably conditions are chosen so that the voltage drop across the pattern is of such a low value that it is not dangerous to human contact, that is usually below 50 volts.

Because of these characteristics they are specially useful in cases in which heat can speed up such an operation as drying or chemical reaction or both, without the risk of the disturbances which can occur if a certain critical temperature depending on the particular case is exceeded. The uniform heat distribution obtained with such films avoids hot spots and thus enables the film as a whole to be carried up to a temperature not far short of the critical temperature thus enabling the maximum of heat to be used with the minimum of risk.

a ti ularfi f us a e the shanaiasa t anatqta f t.

of hair (i.e., waving of straight hair and straightening of curly hair), the operation of absorption type refrigerators, and the drying, setting and curing of materials, especially those involving chemical reactions, such as paints, synthetic resins and other plastics, especially in cases in which the film remains part of the finished structure so that the structure can be reheated at any time.

In all cases in which it may be desirable the film and any layers which may be used on either side may be of mesh or otherwise perforated form to permit or facilitate the passage of fluid such as vapor through it, for instance a solvent in the .m sr a a d "saw The invention will be further described with reference to 7 FIGURE 4 illustrates the application of the invention tothe drying of paint,

FIGURE 5 illustrates the application of the invention tothe curing of plastics.

FIGURES 6 and 7 illustrate developments of the conductive pattern of the films of FIGURES l and 2 respectively,

FIGURE 8 is a detail section illustrating a further development,

FIGURE 9 illustrates the application of the invention to an absorber type refrigerator,

FIGURE l0 illustrates the application of the invention to a hair curler.

FIGURE ll illustrates the application of the invention to another form of hair curler, with the two parts separated,

FIGURE 12 illustrates a box to contain a set of the curlers shown in FIGURE 1 1,

FIGURE 13 illustrates two sets of the curlers in use,

FIGURE 14 is an enlarged detail of the transformer used in FIGURE 13. i

FIGURE l5 is a form of clamping member alternative to that of FIGURE 1 1,

FIGURE 16 is a plan view,

FIGURE 17 is a side view,

FIGURE 18 is an end view and FIGURE 18a is a section on the line XVIII-XVIII of FIGURE 16, of a device according to the invention for the straightening of hair.

FIGURE 19 illustrates the film used in the device of FIGURES 16 to 18 FIGURE 20 is a perspective view of a stackable plug member for use with the device shown in FIGURES 11,15 and 16 to 18.

FIGURE 21 is a side view and FIGURE 22 a section on-the line XXII-XXII of FIGURE 2] of a comb heatable in accordance with the invention, and

FIGURE 23 illustrates a stage in the preparation of the heating film used in the comb of FIGURES 2i and 22.

In the form shown in FIGURE 1 the conductive pattern is an electrical resistance means comprising a film including a thin flexible metallic foil 11 having a series of slots 12 which leave a plurality of parallel meandering paths extending from terminals 13 constituted by the areas along the sides of the pattern. If the width of the arms of the pattern is kept constant each meandering path from one terminal 13 to the other will present the same overall resistance and the same resistance per unit length and if a voltage is maintained between the terminal areas the same current will flow in each path whatever the length of the film. There will thus be a substantially constant dissipation of heat per unit area over the whole film. The film shown in FIGURE 1 can moreover be cut into narrower pieces since any portion between adjacent lines of slots can serve as a terminal. It will be clear that however many meander paths are left between the terminals the cross sectional area of the terminals is greater than that of the arms of the meander pattern so that the development of heat in the terminals is less then elsewhere. The same result can be obtained by adding metal of higher conductivity to the terminal areasas by clamping or plating.

In FIGURE 2 the pattern is similar to that in FIGURE 1 but the slots 14 extend across the foil 15 and the terminal areas -16 are at the ends. Such a film can be cut into piecesby 0 pie.

In general the structure in connection with which the film is used will be a multi-layer structure of which one layer is a layer containing an absorbed fluid to be heated, and the structure at the time the current is switched on will be at room temperature. Where the heating operation causes vapors to be driven off and these vapors have to escape on the same side as that to which the heating film is applied the heating film will have small passages through and it will be made porous or perforated as indicated at 19, FIGURES 1 and 2, to allow for the passage of vapor without harm to it or the structure on which the film is used. Such small passages may be useful in other cases. In many cases the heating film itself will be of cheap construction so that it can be thrown away after once using but the invention also includes cases in which the film is retained for repeated use whether in connection with the same layer or by transfer from one layer to another. Often the heating film is provided with an adhesive coating; for example, a self-adhesive pressure sensitive material to permit easy fixing to the structure.

It is desirable to ensure that if the film is to be used repeatedly but on different layers it can be transferred from one to another without suffering damage because if the pattern is damaged and is still conductive, the distribution of resistance will be affected and there will be a risk of hot spots. If on the other hand it is made of cheap construction so that it can be thrown away it should be desirably made so flimsy that it is practically impossible to avoid destroying it in removing it after use.

In all cases where the pattern can be contacted by a human operator it is so designed that the necessary heating effect can be obtained by a supply of electric current at a low voltage, that is to say at a voltage which does not constitute a risk to the operator if he comes into accidental contact with the matters. Such voltages are usually below 50 and often well below 50 say 12 volts, 6 volts or even lower. Such voltages also make it permissible in many cases e.g. where the layer to be dried is not conductive, to allow the layer to touch the bare pattern. These voltages have the advantage of simplifying the construction of the film and its use, since the insulating problems presented by high voltages do not arise. It also makes it possible to use the heating films for such domestic purposes as the drying of foot-wear, clothing, towels and the like or other textile fabrics.

Other fields of use are in connection with the drying and curing, or the drying, curing and heating of paint and similar materials, and of plastic structures and fabrics.

Thus one major field of application of the heating film is its incorporation in structures which are painted. The incorporation may be temporary or permanent. It is proposed for instance, to stick a heating film 21 FIGURE 4 on the underside of sheet metal work indicated at 22 before it is painted as at 23. Since the workpiece is metallic there must be an insulating layer between the actual pattern and the workpiece as at 24, but this may be part of the heating film. No insulating layer is shown on the other side of the film 21 but it can be provided if desired. The paint is now dried by supplying current to the heating film instead of by the present methods of stoving the panels or applying heat to them by other means. Since metal is a good heat conductor, the heat from the film 21 reaches the part 23 without a steep temperature gradient or in other words the part 23 brought to a temperature a little below that reached by the film 21 and due to the layout of the conductor in the film 21 the heating is substantially uniform over the whole surface. This not only gives an improvement in drying or curing conventional paints but it often permits the substitution ofstoving enamels for air drying paints.

Another major field of application is the incorporation of the film in plastic structures and fabrics such as low pressure laminates, articles made with potting resins, plastic castings and larger scale mouldings requiring heat for quick setting. FIGURE shows by way of example an embodiment with the heating film 25 (which here can be a bare foil pattern) between two layers 26 of fibre-glass and uncured resin i.e. within the thickness of a plastic structure. The slow drying and curing process of these plastic fabrics is at present hindering the use of these in many industries requiring speedy output from the moulds, presses or jigs for their formation. Thus the production of glass-fibre structures by the so called wet-lay process is restricted for mass production applications by the LII practical difficulty of and equipment required for accelerating the heat drying and curing of the structure. The incorporation of the heating film in such structures enables them to be dried and cured quickly and the moulds to be liberated more frequently with consequent saving in floor space and equipment. Heating films incorporated in plastics preferably have small passages (i.e., small holes or pores) through which the fluid resin can flow.

It should be mentioned that the term plastic is used herein to indicate not only materials which when cured are substantially rigid but also materials which are elastomeric, such as natural and synthetic rubber, and polyvinyl chloride.

The invention can be applied to twostep processes in which evaporation of a solvent is succeeded by curing. An example is a fabric such as cotton cloth coated or impregnated with thermosetting resin in a solvent. The resin may be an alcohol-soluble phenolic and the solvent an alcohol with, say, a boiling point at 78C. The resin layer alone may be one which can be cured suddenly, that is within seconds by raising it to 150C., while the fabric cannot safely be exposed to more than 150C. In such circumstances the heating film is first operated to raise the layer to say 70C which results in all alcohol evaporating quickly but gently before the resin can set and immediately the film is dry of solvent raising the heating film to 120C at which temperature the cure is complete after some minutes.

Other resinssolutions may be treated in a similar way. For instance, a surface coating to be produced on an aluminium sheet using the epoxy resin Araldite" 985 E (supplied by Ciba A.R.L. Ltd., Duxford, Cambridge) in a solvent mixture. The heating film (made with asbestos paper and sodium silicate as an insulating support for the conductive pattern) is fixed permanently or temporarily to the back of the aluminium sheet and first raised to below the boiling point of the solvents. If it were then raised to 340-350C it would effect the curing of the resin in less than one minute but tests at this temperature of sudden transition have resulted in uneveness, discoloration, local brittleness and adhesion failures. Raising the heating film to 240C however resulted in a good film in just over 10 minutes. Not all resin solutions require a two or more stage heating. A urea formaldehyde glue applied to a veneer which is laminated to a wooden base will serve as an example. The glue is an aqueous solution of a urea formaldehyde and a hardener such as ammonium chloride. It is not required to evaporate the water first; it disappears into the wood and the heating film can be operated to give a temperature of 120C at once. The sudden' curing temperature of the glue is much nearer to 150C but this temperature would damage the wood and be too great a risk for the urea which rapidly deteriorates around this temperature.

The following are examples of substances which have a much narrower range of temperature for the physical or chemical reaction characteristic of them.

a. Gelation of P.V.C. paste.

The paste consists of a paste polymer (suchas G eon 1 21 supplied by British Geon Ltd.) which is a powder with particles of 1 to 2 micron size, ester plasticiser (such as dioctylphthalate or trichresylphosphate) and a stabiliser (such as dibasic lead sulphate). It has a fusing temperature of 170C which is also the limit or near the limit of the temperature endurance of the gelled film. The heating film operated to attain C gells the paste within a few seconds in safety.

b. Sintering of Teflon emulsion.

This emulsion of polytetrafluoroethylene contains discrete fine particles which must be heated for a very short time only to 450C to sinter together. Local overheating causes breakdown of material while a temperature substantially lower fails to cause sintering.

C. CHEMICAL BLOWING AGENTS such as Genitron A.C. an axodicarbonamide (supplied by Whiffen & Sons, Ltd., North West House, Marylebone Road, London, N.W.1) are often incorporated in pastes or rubber mixtures. They decompose at a certain temperature and expand due to liberation of nitrogen. When, as it is usually the case, this blowing action is to be utilised to produce pores in the substance the time-temperature conditions of the cure have to be so related to the blowing temperature that the nitrogen does not simply escape because the substance is still too liquid when the blowing agent decomposes. Nor must the substance already be set and hardened and not permit the pores to form.

The blending of the various ingredients to match desired hardening and decomposition times and temperatures is particularly difficult for thin layers and in these cases the method of the invention is of great help. The very low thermal inertia of the heating film and its homogeneity and thinness often permit stepped heating and stepped cure. It is, for instance, possible to first heat the paste film to a viscous consistency which will still permit pore formation without danger of gas escape and then quickly raise the temperature to that of decomposition of the blowing agent and subsequently continuing the full cure at the same or at a lower temperature, if necessary.

Further examples comprise substances coming between the two previous groups. They are, for instance, solventless films of resins and hardeners or elastomeric compounds in which the method of the invention does not so much bring a marked improvement in the control of the physical and chemical reactions apart from their acceleration but does afford other savings and advantages.

The case of resin impregnated glass fibre mouldings is described in this specification at a later stage and the examples given are only typical. Usually the impregnant is a solventless polyester, epoxy, silicone resin or another compound the cure of which can be accelerated by heat below the rate at which the setting and hardening is a matter of seconds for a thin film.

in the case of an absorption refrigerator, since the method of the invention enables the heat to be applied over a very large area, the times of the alternate phases of absorption of the vapor and of regeneration of the solid can be substantially shortened. In this particular application the film will be porous or perforated and is preferably made into flat bags which enclose a very thin layer of the absorbent solids and therefore presenting a maximum surface of the solids both to the vapor coming from the evaporator and to the heat carried at a high rate to the solid from the large surface area of the film.

A suitable arrangement is shown in FIGURE 9. Between a pipe line 35 leading from the evaporator and a pipe line 36 leading to the condenser, the pipe is formed into two

branches

37, 38 interlinked change-over valves being provided at 39, 41 so that at any instant one branch is connected to the evaporator and the other to the condenser. In the position shown the branch 37 is connected to the evaporator and the branch 38 to the condenser. in each branch is carried a heating film bag 42, 43 confining the absorbent powder in a thin layer. The film is porous but the pores must be of such size that they do not become choked by the powder. In the position shown the film 43 is being heated so driving off the absorbed vapour to the condenser while the film 42 is not supplied with current and the solids are absorbing the vapours coming from the evaporator. The supply of electricity to the two films is controlled by switches interlinked with the valves 39, 41. The two-branch arrangement and the cycle of operations provides for a constant flow from the evaporator to the condenser, but by using 4, 6 or 8 branches instead of only two and arranging for the periods to overlap, the vapour flow can be made still smoother.

The branches are preferably very shallow metal bodies with very large surfaces which may be air or water-cooled. Cooling fins are diagrammatically indicated at 44. it will be understood that the figure shows the narrow depth and the length of the branches and that they also extend to a considerable width in the plane perpendicular to the drawing. The bags constituted by the film 42, 43 are of flat form fixed in the central plane of the branches and extend practically over the whole length and width of the branches. The heating film temperature need not rise much above the temperature required for regeneration and the small mass of the film enables it to cool and heat rapidly so that changes from one phase to another both on the film and in the powder can take place very quickly. This property together with the large surface area of the film enables absorption refrigerators of larger capacity to be built than at present possible.

The present invention can also be applied to the drying of wearing apparel of any kind from hat to shoe. Such devices as inserts or covers for all sorts of clothing including tiestretchers, shoe-trees and shoe-cases, may be provided with the heating film. At present such devices are mainly used as purely mechanical aids to fix, stretch or hold the clothing in position or bring it into a desired shape while it is air drying. For these purposes a porous or perforated heating film with ample openings is used which is connected to a source of very low voltage (battery or secondary of a transformer) to be incorporated in or attached to the above devices either permanently or as a dispensable item (to save cleaning or the expense of making them robust).

In the hair curler shown by way of example in FIGURE 10 a plastic material reinforcing and supporting the heating film is made thick enough to form the ovoid body 45 round which the hair is wound and fixed, the connecting cable being indicated at 46, a plug connection at 47 and the supply here being exemplified by the secondary of a transformer 48. It will be un' derstood that both the film and the plastic reinforcing material have square or similarly shaped openings giving them the same meshed form and that the reinforced film itself is rolled up and shaped to form the ovoid body 45. The same scheme is equally applicable to other well known forms of hair curler, e. g. cylindrical or fiat.

Another and preferred form of curler is shown in FIGURE ll. Here there is a meshed roller 51 of conventional form forming a support for the hair when wound on it, while theheating film not visible as such is embodied in a spring clamp 52 of part cylindrical form which can be sprung over the roller after the hair has been wound on the latter, not only applying heat but also pressure. The clamp is meshed to match the pattern of the film so that the vapour from the solution commonly used in hair curling can readily escape through the roller and through the clamp. A tape form connecting cable is indicated at 53.

A set of say ten such rollers and clamps may be stored in a box 54 provided with a shoulder strap 55. The several cables 53 from the clamps are carried into the box which is provided with an external lead 56 for connection to the supply and a switch 57, suitably a four position switch giving off, low, medium and full heat. in the low position all the clamps could be in series or two groups each of five in series could be in parallel. in the medium position two groups each of five in series could be in parallel, or five groups each of two in series could be in parallel. in the full position, five groups each of two in series could be in parallel or all ten be inparallel. Even under full heat, no point in the clamp should rise to a temperature at which damage will be done to the hair or skin of the user, but the film will enable a substantially uniform temperature to be reached over the whole area of the clamp. Other numbers than ten per box may be used with corresponding changes in grouping for the various heats. There may be fewer or more heats. Also the heat control could be in the transformer instead of in the boxes.

FIGURE l3 illustrates the rollers and clamps associated with two boxes 54 in use simultaneously, one box being hung over each shoulder. The supply is drawn from conventional AC mains by a plug and socket 58 and its voltage reduced by a transformer 59. As shown in FIGURE l4 the transformer has a pilot lamp 61 to indicate when it is live and two sockets 62 ,to receive plugs 63 associated with the leads 56 for the two boxes 54. The time and extent of heating are under the immediate control of the subject or of a hair dresser. Also the subject can at any time move away temporarily without disturbing the curlers by withdrawing the plugs 63. I

An alternative to the external clamp 52 of FIGURE ll is shown in FIGURE 15. This is a heated expanding spring car tridge 64 of thin sheet material meshed to match the heating shown. This thin sheet material of the cartridge is shaped into 'a substantially heart shaped cross section and is of such size that it is compressed slightly when in position within the roller. To facilitate its sliding entry into the roller it is slightly tapered longitudinally as can be seen in FIGURE 15. The taper could be confined to the leading end. When such a cartridge is used other means such as an elastic band may be necessary to hold the hair on the roller.

It will be understood that curlers employing the cartridge of FIGURE can be boxed connected and controlled as described with reference to FIGURES l l to 14.

There is a demand not only for hair curling devices but also for hair straightening devices and the invention provides those. The straightener shown in FIGURES 16 to 18 comprises two flat jaws 65 hinged together and urged together by a spring 67 of C section. Each jaw is integral with a handle 68, and the parts so far are held together by the spring 67 which also serves as a hinge, as in a well known type of paper clip, except that the jaws are moulded of hard plastic so that they are of insulating character. A heating film 66, see also FIGURE 19, is of generally U form with its limbs lining and secured to the jaws 65 say by adhesive or even moulding in near the surface. Parts 69 of the busbars of the film are partially severed and carried out to an external part cylindrical shroud 71 to which they are secured by screws 72 embodying press stud halves by which connection can readily be made by leads 73 to the supply. The shroud 71 is of thermally (and electrically) insulating material e.g. a moulded plastic, and is sufficiently spaced from the jaws 65 to avoid hindering opening of the jaws and sufficiently embracing to avoid external contact with the jaws thus preventing burning of the subject's skin or damage to furniture on which the device may be temporarily laid.

In use, the hair will be held straight with a comb and the jaws 65 closed upon the hair while so closed. Heating is then effected, usually after prior application of a solution just as in curling, curling and straightening being inherently physically indentical processes in that they give the hair a predetermined form differing from that which it has naturally.

A plurality of straightening devices can be stored in a box or boxes and the heat controlled just as above described with reference to FIGURES 12 to 14.

Instead of being separately connected to the control switch or transformer, each curler or straightener can be provided with its own plug fitting such plug fittings being stackable, for example as shown in FIGURE 20 with two pins 74 and two sockets 75 to receive the next fitting. [n the simplest case these fittings may simply establish parallel connection to each connected curler or straightener or groupings (in which cases the transformer secondary may be switchable for fast control but they may be designed to provide alternatives as by the incorporation of switches or alternative pairs of sockets. With any of these control arrangements for a set of curlers or straighteners the control may be operated by an automatic timing arrangement or there may be individual thermal cut outs followed by a timed switch off. The timing can be so programmed that the hairdresser can undo the first curler or straightener just after he has put in the last. The timed switchoff would proceed however irrespective of the hairdresser keeping to schedule. Thermostats or heat sensing elements in the curlers or straighteners are alternative safety provisions.

Another device by which heat or pressure can be applied to the hair (while if desired a solution is also applied) is a metal comb shown in FIGURES 21 and 22.

The comb has a back 76 which is wide in the direction of the length of the prongs or teeth 77 and of substantial thickness so that there is good heat conductive connection from the back to the teeth which are mechanically rigidly connected together, being made integral; a suitable metal is brass.

An electric heating film 78 is bent in U form and embraces and makes good heat conductive contact with, but is electrically insulated from the greater part of the area of the comb back 76 on both faces. A triple layer film i.e. metallic foil with thin insulation on both sides may be used and it may be secured by adhesive. The outer faces are covered with a layer 79 of plastic foam thermal insulation thus conserving the heat while to protect the user the comb is provided with a plastic handle 81.

To make good connection to the film, before it is folded (on the line 82 FIGURE 23 the busbars are bared at 83 and apertured at 84. When folded onto the comb back as in FIGURE 22, screws 85 are put through, and metallic washers 86 are drawn up tight by nuts 87 forming press stud halves by which leads 88 to a supply are readily connected. To avoid short circuiting to the comb itself, the screws 85 are insulated by filler pieces 89 of larger diameter than the washer 86.

A similar scheme may be used to provide a heatable hair brush. This will have metallic prongs forming the bristles mechanically rigidly secured, e.g. to a back plate or body e.g. integral therewith, the back or body being incorporated in a brush back say of plastics, and a heating in good heat conductive contact with the metal back plate and leads connected thereto similar to the leads shown in FIGURES 17 and 21.

I claim:

1. Device for bringing hair into a predetermined form which comprises a support on which the hair can be held in the predetermined form, means for holding the hair against the support whereby it is retained in the predetermined form, an electrical resistance means comprising a heating film secured to at least one of said two integers, namely said support and said holding means, said film and integers forming an assembly having perforations distributed over it on at least one side of the hair held therein to permit the escape of fluid, said heating film extending over an area approximating to the area of the support over which the hair is held and the major part of the area of the film being occupied by an electrically conductive material having a surface pattern uniformly distributed, the electrical characteristic of the film being such that when energised from a supply at a voltage under 50 volts, its temperature will be raised substantially without at any point on the film reaching a value which would cause the hair to be damaged, and connecting leads for connecting the film to a supply of electrical energy.

2. Device as claimed in Claim 1 for waving hair wherein said support being of meshed form for the hair, the film being secured to the support and being meshed to match the support.

3. Device as claimed in Claim 1 for waving hair wherein said support is a roller support of meshed form on which the hair can be wound and said holding means comprises a spring clamp adapted to be sprung on after the hair has been wound on the roller support, said heating film being secured to said clamp and said clamp and said film being meshed to match one another.

4. Device as claimed in Claim 1 for waving hair wherein said support is a roller support of meshed form on which the hair can be wound and retained and said hair holding means is an expanding spring cartridge slidable within said roller support and expanding thereagainst, said cartridge and film being meshed to match one another.

5. Device as claimed in Claim 4 therein said cartridge is of thin sheet material shaped into a substantially heart-shaped cross section and has a slight longitudinal taper to facilitate sliding entry into said roller support 6. Device in accordance with Claim 1 comprising a plurality of said supports for hair held in the predetermined form, said holding means comprises a corresponding number of spring urged meshed members each carrying one of said heating films meshed to match therewith and each adapted under the spring action to ensure good heating conductive connection of the heating film over substantially its whole area with the hair on the corresponding support, a transformer whereby a supply drawn from conventional electricity mains is transformed down to the requisite voltage for the heating films, tape cables connecting all of said films to the secondary winding of the said transformer, and regulating means whereby the voltage supplied to the individual heating films canbe regulated.

7. Device as claimed in Claim 6 wherein said regulating means comprises means for switching said heating films into a selected one of a plurality of electrical groupings selected from series, series-parallel, and parallel connection.

8. Device as claimed in Claim 6 also including at least one box each adapted to contain a plurality of said supports and spring members when not in use, the films on the spring members associated with the box being connected to said voltage regulating means carried in the box, and said regulating means having a single tape cable lead and plug and socket connection to said transformer.

9. Device as claimed in Claim 1 for straightening hair wherein said support and said holding means constitute flat jaws, hinged together, said device also including a spring urging said jaws together.

10. Device as claimed in Claim 1 for straightening hair wherein said support and said holding means constitute flat jaws of two combined jaw and handle members hinged together between the junction of the jaws and handles by a C- section spring engaging said jaws and urging them together, and an external part-cylindrical shroud of thermal insulating material sufficiently spaced from said jaws to avoid hindering the opening thereof and sufficiently embracing to prevent undesired external contact with said jaws.

11. Device for applying heat and pressure to hair comprising prongs of metal, a substantial metal body connected in good heat conductive and mechanically rigid connection with said prongs, an electrical resistance means comprising a heating film, means holding said heating film in firm heat conductive contact over substantially the whole area of the film with said body, the major part of the film being occupied by an electrically conductive material having a surface pattern uniformly distributed but insulated from said body, the electrical characteristic of the film being such that when supplied with energy from a supply at a voltage under 50 volts its temperature will be raised substantially without any point on the film reaching a value which would cause the prongs to damage hair or skin with which it comes into contact, and connecting leads whereby said material can be connected to a supply of electrical energy. I

12. Device as claimed in Claim 11 wherein said prongs are metallic brush bristles and said body is incorportated in a hairbrush back.

13. Device as claimed in Claim 11 wherein said prongs are comb teeth and said body constitutes a comb back integral with said teeth, of substantial thickness and of substantial width measured lengthwise of the teeth, and said film is of U form with the limbs clamped against opposite faces of the comb back, the comb also including thermal insulation on the outside surface of both limbs of the film.