4 to 6 g m 2 the color former and color developer reagents are prepared as described in example no 1 where the pigment paste is based on calcium carbonate prepared by moisturizing as described in example 3 the resulting paste is finished at 50 solids in this example the purpose is to make the aging resistant paper achieve a lasting image which is developed through antioxidant papers which avoid yellowing and a loss of image the final mixture comprising the thermo sensitive layer is deposited through the coating rod mechanism the preparation of the reagents color former and color developer are prepared as described in example no 1 in this example the pigment paste is based on calcined kaolin prepared by moisturizing as described in example 3 this example shows the difference between papers presenting a resistance to aging as in the thermo sensitive layer of example 4 each one of these examples was prepared according to example no 1 utilizing the equipment described the size of the particle should be between 2 0 and 2 5 microns thermal color preparations developed in this way were applied on two types of paper using rod no 6 to deposit an average of 4 to 6 g m 2 viscosity was adjusted in every results of these examples appear in the following table densitometer were used to evaluate the image intensity examples 1 to 6 were covered over two different types of paper one pre coated with a kaolin coat and natural and synthetic adhesives such as starch and styrene butadiene latex and a paper without coating but presenting high smoothness on one of the faces which as mentioned elsewhere occurs mainly because during the manufacturing process and.