the screen spacers of the mesh size and wire diameter described above are preferably 1 inch wide and are preferably located at 2 inch centres across the casting width of the objector they are attached to the fixed support structure and extended in the casting direction to about 1 4 inch short from the downstream edge of the refractory tip screen spacer strips are used for convenience of installation and replacement after use when wear of the wires at the contact points with the belt reaches a maximum limit however a continuous screen across the entire casting width may alternatively be used if desired for example to maximize the cycle between replacements when very high metallostatic pressures are employed because the screen structure accommodates thermal expansion differentials without significant warping which may result in localized excessive contact pressure and wear and in extreme cases in loss of reliability and accuracy of the spacing function as it has been found to occur sometimes with solid spacers further advantages of the screen spacer are that while the points of contact with the belt are small the weight of the injector is distributed over the considerable width of the spacers and so the actual loading on each wire 47 can be kept is reasonable therefore there is no observable scoring of the belt by the spacer further the screen spacer is very flexible so that it easily follows the contours of the belt surface coupled with the use of a flexible injector as described above this means that the.