Verificou-se a expansão de um revestimento em função do tempo de vazamento de uma segunda mistura sobre o mesmo. As alterações dimensionais do revestimento interno foram verificadas através de um microscópio de mensuração. Determinou-se que a expansão de presa do revestimento interno é afetada ao ser coberto por outro revestimento, encontrando-se maiores valores quando a aplicação é feita no momento da sua presa

The purpose of this work was to verify the influence of pouring time variation of the second mixture of investment on the inner investment expansion, when the double investing technique is employled. The dimensional changes of the inner investment was measured through the use of a Carl Zeiss microscope, 00,1mm precise. A shield of acrylic resin was made on a glass slab and 50 mm from it a slider transmited the dimensional changes. The shield and one end of the slider were covered with investment. the second mixture of investment was poured 5 minutes before the setting time, during the setting time and 5, 10, 15 Jand 20 minutes after the setting time of first mixture. The analysis of variance allowed us to conclude that: 1) the expansion that follows the setting reaction of the investment is affected by the second pouring of investment: 2) this expansion depends on the time of pouring the second mixture of investment; the highest values occur when the second mixture is poured during the setting time of the first one; 3) all the values obtained are higher in relation to the setting expansion and lower to the hygroscopic expansion of the first mixture of investment; 4) a half an hour should be allowed before pouring the second mixture to avoid an exagerated influence on the expansion of the first mixture.