Abstract: An improved clot activator system for reducing the clotting time for blood samples in serum separation tubes, and the like, as well as increasing the degree of clotting, while at the same time, reducing the cost of production. This is achieved by the addition of glass pieces to the tube which pieces are formed in a particular way by a sol-gel process. The particles are pieces of glass, and are a porous substantially rigid amorphous inorganic sponge with substantial reactive surfaces. When a blood sample is introduced into a serum separation tube containing such pieces, the blood enters the interstices of the pieces causing fragmentation thereof, which fragmentation causes sound and shock waves which, in turn, enhance the clotting of the blood.

Abstract: A process is provided for enhancing the uniformity of silica coatings on substrates, such as evacuated blood collection tubes for example, which increased uniformity results in a substantial increase in the active surface area of the silica for improved clot activation. The process includes hydrolyzing a mixture of ethylsilicate and isopropyl alcohol in the presence of an acid or alkaline solution to precipitate out the silica. The silica sol which results is applied to the substrate, and dried in the presence of low heat application. Alternatively, the silica sol may be mixed with a water soluble carrier such as polyvinyl pyrrolidone, if desired, prior to application to the substrate, if the silica is to be released into a water based substance, such as blood, for example subsequently introduced into the coated container.