Blueboard is analogous to drywall but is used as a base for plaster finishes. It is very similar to drywall in the sizes they come in, the fact that it is cut with a knife, it is fastened to the wall the same way as drywall, and it has the same core material. But the similarities stop there as the main difference is the paper the sheeting is covered with. The Blueboard's name refers to the color of the special paper that covers it and which is chemically treated to bond well with a skim coat of specially formulated plaster. When you finish Blueboard, a quick tape-and-plaster approach is used on the joints seams followed with one or two coats of plaster veneer to the entire wall surface.
To install blueboards inside a room, measure the width, length, and height of the walls and ceiling. Obtain a supply of boards and cut them to fit. Screw the blueboards into the studs with drywall screws. Push double-sided tape into the joints between sheets. At this point, however, the job takes a different turn. The paper used to coat blueboard is slightly different than the paper that coats sheetrock. Drywall paper absorbs paints readily but blueboard paper is designed to chemically bond to a plaster veneer. Blueboard with the veneer plaster can run 20 to 30 percent more than drywall installation and requires specialized equipment and skills.
Step 1 – Prepare Blueboard and Plaster
Cut any necessary openings for plumbing and electrical fixtures, then screw the blueboard into place and tape the joints to prevent the wall from cracking later. Measure the surface area of the room and obtain enough plaster to finish the job. Use specially formulated veneer plaster, which contains lime and other additives to catalyze the binding reaction. The job will cost 55 to 70 cents per square foot. Do not mix the plaster before you're ready to begin applying it. The plaster hardens quickly so the operation is very time-sensitive.
Start at the ceiling and work your way down. On the ceiling, begin by plastering along the taped joints. Lay large dollops of plaster mix on the ceiling and smooth them out with the trowel. Try to spread out a layer that is 1/16-inch to 1/8-inch thick. Doing this correctly takes practice. Work quickly, but use long, fluid motions. Depending on the season and weather, the plaster will begin to harden in 1 to 2 hours. You will notice it developing a brownish tint as it hardens. After this time, you can moisten the plaster by spraying it with water and brushing the water in. This technique can help you finish up but you don’t want to overuse it or the quality of the finished wall could suffer.
Step 3 – Apply Second Coat
After you have plastered all of the ceiling and walls, start a second coat from the beginning. The second coat is not as thick as the first. In fact, as you are applying the second coat, use your trowel to remove excess lumps and smooth out the plaster.
Step 4 – Allow to Dry
There is no need to sand the plaster in between coats. The plaster will dry completely in 1 to 3 days depending on humidity. Paint the wall once the plaster is dry. Sanding the wall before painting is optional.