found that mulling the mixture for about five minutes yields a very satisfactory product after the coreactant has been added the mixture should be mulled for another short period but care should be taken not to heat up the mixture by excessive mulling because such heating could accelerate polymerization of the resin fig2 shows a block 19 formed by combining granular material colored by three different paint colors but instead of having the colors separated from each other in flat layers as in fig1 the colored materials 21 23 are intermingled with each other the intermingling is done carefully so that each small region is visibly distinct and has relatively sharp boundaries this is achieved by forming at the same time three different slurries of granular material colored by three different paint colors and mixing all three together while all are still in the liquid state the mixing must not stir the three colors so intimately together that the block 19 will appear to have just one color which is the additive result of the three color components the colors should be kept separate so that the visual effect is that the block 19 somewhat resembles marble with a main region 21 that appears white in this figure and other regions 22 and 23 colored by two different paints.