An important factor influencing sealant performance on the outside of buildings is the cyclic movement induced by daily and yearly temperature changes. Although the sealant itself expands and contracts with temperature, these dimensional changes are negligible and largely reversed by changes in the building elements surrounding the joint. At the present time sealant manufacturers suggest that for the best quality sealants, joints should be designed with such width that the movement produced in them by the surrounding building elements will not be more than plus/minus 25% of the joint width. The exposure rack here described produces various amounts of movement covering a range reaching beyond 25%. The cyclic movement of the rack is produced by changes in weather conditions that induce different amounts of movement in two kinds of metal used in the construction of the rack.