the frying pan shown in fig1 is of conventional overall design and comprises a body 2 and a handle 4 . the body has a lower heat receiving surface ( not visible in fig1 but shown as 22 in fig3 ), and an upper cooking surface 6 . the upper cooking surface 6 is formed with a pluarity of closely spaced corrugations 8 , shown more clearly in fig2 and 3 . the pan body itself is normally made from a single piece of material , either cast or machined , and can be adapted for use either with open flame stoves ( gas ) or electric ( unit or &# 34 ; smooth - top &# 34 ;) cookers where the underside of the pan will be machined flat to ensure good contact with the electric heat source . the corrugations shown in fig2 are in the form of concentric circles , although any pattern may be adopted . circular corrugations have the attraction of being easily machined into the surface of the pan and having no sharp bends therein . straight corrugations can be adopted , particularly in square or rectangular pans . a pan made of a suitable material and being formed with corrugations according to the invention offers substantial advantages over known flat surfaced pans . these benefits can be enhanced , however , by the application of a &# 34 ; non - stick &# 34 ; material to the corrugated surface . the construction of a pan base according to the invention , and with such a surface , is shown in more detail in fig3 . as shown in fig3 the body of the pan is formed with surface corrugations 8 . these can be ground or machined into the surface by conventional means , and the sharp corners at the peaks and troughs have been removed . a continuous layer 10 of polytetrafluorethylene is then applied to the corrugated surface , also in a manner known per se . again , these sharp corners at the peaks and troughs of the corrugations are removed such that the exposed cooking surface is relatively smooth . towards the right of the figure , the results of long use and abrasive cleaning is illustrated . as can be seen , the peaks of the two corrugations 8a and 8b have been worn away , but only the peak corrugation 8b is worn away to such an extent that the base metal of the body 2 is exposed . initial wear increases the exposed area of &# 34 ; non - stick &# 34 ; surface , and even after prolonged wear only a small area of the base material is exposed . once the base material is exposed , then as this material ( e . g . anodized aluminium ) is considerably harder and more resilient than the &# 34 ; non - stick &# 34 ; material , the rate of further erosion of the corrugation peaks is reduced . it will be noted that in the valleys of the corrugations , the &# 34 ; non - stick &# 34 ; material will suffer little if any erosion . benefits similar to those described above can be achieved by forming a generally rough base surface , rather than one which is specifically corrugated . in this context , &# 34 ; rough &# 34 ; means the creation of distinct spaced peaks and recesses , as against merely a key for the subsequent application of a &# 34 ; non - stick &# 34 ; surface . in a surface roughened in accordance with this aspect of the invention , the peak to valley spacing will be for example , of the order of 1 to 2 mm , normally no more than 1 . 5 mm , and the exposed &# 34 ; non - stick &# 34 ; surface can be substantially smooth . once again , the use of cleaning tools will predominantly erode the &# 34 ; non - stick &# 34 ; material , but erosion will be reduced once the peaks of the base material become exposed . it will be appreciated that the rough or corrugated surface can extend into and up the side wall or side walls of a cooking pan , and this will be a particular benefit in ovenware . while the invention has been particularly described above in connection with a frying pan , it is readily adapted for use in other pans or indeed , any cooking utensil in which adherence of foodstuffs to a surface is a problem . for example , it may also be embodied in griddle pans which are a permanent component of a piece of cooking apparatus . another example is shown in fig4 where a saucepan or baking pan is provided with a cooking surface 6 having a pattern of corrugations in the form of a plurality of concentric circular grooves 12 superimposed on an overall pattern of grooves 14 . the side wall 16 of the pan is formed with straight corrugations 18 . between the corrugations 16 and the grooves 12 and 14 at the junction between the side wall and the cooking surface , a smooth annular area 20 is formed . this region is least subject to contact by cooking implements , and a smooth surface here is sufficient to minimize adherence of foodstuffs thereto . all the inner surfaces may be coated with a non - stick surface to achieve the additional benefits of the invention as described above . the inclusion of a smooth annular region 20 can be incorporated in all embodiments of the invention between the contact surface 6 and a side wall of the pan . the embodiments of the invention described are by way of example only . various modifications thereto may be made within the spirit and scope of the invention . particularly features of one embodiment may be adopted in the other or individually while still benefiting from the invention defined herein .
in order to reduce the tendency of foodstuff to adhere to a cooking surface , that surface is provided with an uneven surface formed with closely - spaced peaks or corrugations , normally in the form of concentric grooves . the surface may additionally include a layer of &# 34 ; non - stick &# 34 ; material which further reduces the likelihood of foodstuffs sticking thereto .