Organized 1864 For over 150 years the OPCMIA has represented and trained plasterers and cement masons for the purpose of protecting and promoting the quality of our industry and the livelihood of our members. Plaster and concrete are ageless building materials that will not fall out of favor as long as there is a sufficient amount of workers who are skilled in the arts of installation and finishing. These materials are as unforgiving as they are durable and beautiful. Skilled hands and competent management must work together to achieve the desired result and to promote and protect this vital construction resource. We dedicate ourselves to the promotion of these materials, the recruitment and training of skilled craftsmen to meet the demand of our industry, and hold ourselves responsible to this commitment for the future of our industry and the welfare of all those who earn their living in it.