Q&A Column

What is security sealant? How does it differ from other sealant?

Let me begin with a brief explanation of why security sealants are used. Prison inmates frequently try to remove or destroy anything they can. High schools and other public places are often subject to the same abuse. Sealants are an excellent target, as they are softer than other materials. Simple destruction is not the only problem that results from removing sealant; exposed cavities can be used to hide contraband, then hidden by re-inserting the sealant.

Although there is no universally accepted definition, two types of products are commonly used as security sealant. One is a semi-rigid epoxy, the other a urethane sealant that is much harder than others. The characteristic that sets them apart from other similar products is their greater hardness, measured on the Shore A scale. On this scale, a typical bathroom sealant might have a hardness of 18 to 20, while a car tire has a hardness of about 70.

Semi-rigid epoxies have a Shore A hardness of 85 to 90, yet have some flexibility. They are most often used in floor joints, but can also be used in vertical joints. These epoxies are two-component, 100% solids materials, mixed in a one-to-one ratio. Because of their hardness, they work better in compression than in tension.

Urethane security sealants have a Shore A hardness of at least 50. They are available in both single- and multi-component products. The former have the obvious advantage of being easy to use, but are limited in color range (though they can be painted). Multi-component products, which must be carefully mixed if they are to perform properly, have a much greater range of colors.

Both products are produced by several manufacturers, and are readily available.

Answer submitted by Marthe Sandvik, CSI, CDT, Sonneborn Building Products