The glaze on the surface of ancient porcelain is formed by firing and melting natural mineral materials at high temperatures. When repairing damaged porcelain artifacts, colorless and transparent paint is usually sprayed on the repaired parts to imitate the enamel layer on the surface of the porcelain. Currently commonly used imitation glaze coatings generally have two obvious defects:
First, the hardness of the coating film is not enough;
Secondly, the repairing paint has poor weather resistance and tends to suffer from aging and discoloration. Therefore, it is difficult for the coating film to form a good protective effect on the cultural relics after the restoration is completed, and the aging and discoloration of the material will affect the appearance of the cultural relics, and a secondary restoration is required.
Using fumed silica powder materials, the three commonly used imitation glaze paints (nitro paint, acrylic varnish and water-based paint) for ceramic restoration were modified experiments, and it was found that the addition of gas silicon had an effect on the surface hardness of the three paints. Both have a significant improvement effect, and the increase of the surface hardness of the coating film is proportional to the proportion of fumed silica. When the proportion of fumed silica reaches 3% (volume ratio), the pencil hardness of the coating film of the waterborne polyurethane varnish will increase To H; when the ratio is 5% (volume ratio), the pencil hardness of the acrylic varnish coating film is increased to H, and the pencil hardness of the nitro varnish coating film is increased to 3H.
The pencil hardness of the coating film is the core indicator in the research of imitation glaze coatings. Increasing the surface hardness of the imitation glaze coating can make it closer to the enamel layer on the surface of the original object in terms of touch. (According to the industry standard, the hardness of pencil refills is divided into 13 levels. From the hardest 6H to 5H, 4H, 3H, 2H, H, and then to the moderately soft and hard HB, then from B, 2B to the softest 6B).