This paper describes the test results on caulking compounds for buildings. 25 kinds of compounds manufactured by 12 manufacturers in Japan,were tested following to JIS A 5-751 "Caulking Compounds for Buildings,"and the tentative tests, concerning to water and weather resistability, were carried out additionally with some compounds which met to the require-ments of JIS.

According to the test results of JIS, 10 of 25 compounds were rejected.9 of 10 disqualified compounds were rejected by "Bond" test, which was one of the most important tests for caulking compounds.

As to the water resistability, it was recognized that the compound in a mortar joint had a tendency to separate from the surface of mortar,when the mortar got wet after the joint was filled with the compound.This failure has not yet generally been noticed in our country. In order to prevent this separation, it is effective to prime the surface of mortar with alkali resistive primer.

As to the weather resistability, even when the inner parts of all compounds, filled in mortar joints, remained still viscous, the skins of some compounds hardened and cracked. But there was not enough time to get final evaluations. Stains in the skins of the compounds due to oil bleedings,appeared in some compounds during out-door exposure. This was very noteworthy failure of compounds, but did not appear in the weather meter test and in any other tests in the laboratory. Several attempts to find out the cause of this discrepancy were tried but all were fruitless.

* Manuscript received on July 6, 1963.