After about 30 minutes to an hour the basecoat will begin to change color, to “brown” as it begins its to? setĪt this time, some minor imperfections in the surface can be ironed out with the trowel. The basecoat is held off a small distance from the very corner of the bead. This is applied either as a single pass or you can double up with a “sweetcoat” of a small amount of additional plaster if it helps to get a more even coverage of approximately 1/8-inch or just a bit less. This allows the joint area to firm up while a larger mix is prepared for the entire surface. Next is a breakdown of a basic two-coat veneer plaster application over a blueboard substrate that has had mesh tape applied to the joints and cornerbeads on the corners, assuming the substrate is relatively planar and ready to go.Ī small mix of the sanded veneer plaster basecoat is prepared and applied to the joints having mesh tape. Alternatively, in some situations such as when there are curvilinear terminations such as found with windows, various openings and transitions it can be advantageous to customize corners out of gypsum molding plaster, using them as screeds for the veneer plaster to form edges. There are also straight cornerbeads that are specifically made for one and two coat veneer plaster systems. Special fiberglass mesh tapes that have additional, diagonally running threads are also manufactured that provide additional strength for use where the plasterboards abut. The bonding agent can sometimes also be used for other surfaces receiving veneer plasters such as cast concrete. If blueboard is not available, particularly for the thickness of plasterboard sometimes needed, regular drywall can be substituted but should receive a coat of glue known as a bonding agent. The paper for these boards is typically a darker greyish blue color and are known as “blueboard” among plasterers. Unlike regular drywall, veneer base plasterboards are faced with a highly absorptive paper that contributes to a strong bond for plaster. Plasterboards with a special paper are manufactured especially for use with veneer plasters. Veneer Plaster Systems Means, Methods and Specifications It is even possible to forego the basecoat and apply the finish as a single coat veneer. Both the basecoat and finish veneer plasters come ready mixed with retarders that control the set time.Īdditional retarder is likewise available to extend the setting time even further, sometimes useful for large surfaces and production work.
Though, traditional lime gauged with gypsum can and occasionally is still used over the veneer basecoat, a purely gypsum finish plaster was formulated that was a bright white and that could be readily brought up to a polish. The brown coat was replaced with a basecoat, a blend of gypsum and finely sieved sand that allowed the plaster to be applied to a consistent thickness of under 1/8-inch thickness. The gypsum core of the plasterboards began to be entrained with air and mixed with fillers. Within a couple of decades, the veneer plaster systems became thinner and more lightweight.
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