Giving a room a new lease of life by freshening up walls and ceilings starts with a step that precedes painting: plastering. This essential operation prepares the substrate by smoothing it and removing any irregularities that would stand out even more once paint is applied. But this stage can sometimes be tedious. To save time and energy while still producing quality work, several tools are available.
What is a flat box?
This is particularly true for the complex operation of bonding joint tapes, which is essential for high-quality plastering. In all, three steps are required: taping, filling and finishing. For bonding joint tapes on walls and ceilings with a clean finish without spending too much time, the flat box emerges as a very interesting tool.
Also called a finishing box, the flat box is perfect for applying the fill and finish coats over taped joints. Its advantage is that it applies compound evenly in a minimum of time. In essence, a drywall flat box is an automatic taping tool that simultaneously applies joint compound while feathering the edges of the seam, significantly speeding up the finishing process?
How do you apply compound with a flat box?
A little preparation is necessary to apply compound to joint tapes using a flat box. First, make sure you choose a compound suited to the type of job and to the machine you are going to use. For flat-box work, ready-mixed compounds that are easy to apply are often recommended.
The professional should also equip themselves with a trowel or jointing knife to smooth the compound after application. They can also take along 220-grit sandpaper to sand the surface once the compound is dry until an optimal finish is achieved.
Of course, the essential element when applying compound to joint tapes with a flat box is the box itself. The tool is fairly simple: it consists of a compound reservoir and an adjustable head for application. Using it is relatively straightforward compared with other joint-tape application tools. You can fill it with a loading pump, as with a bazooka, a mudshot or sometimes a banjo, but also simply by hand with the help of a syringe.
What technique should be used with a flat box?
The flat box or finishing box is ideal for finishing. Manoeuvrable and easy to use, it accompanies the professional wherever they go without being cumbersome. The compound is deposited and spread along the joint tape using the adjustable head in a single pass. You simply place the flat box along the wall and lay down the compound over the tape by rolling it along with the small wheels on the tool.
Care must be taken, however. Before applying compound to the joint tape, several preliminary steps are necessary, as with any plastering operation. You must first check that the surface to be treated is clean and thoroughly dry. If not, it must be cleaned, dusted and dried. The compound is then prepared in a dedicated bucket, or a ready-mixed compound is used, and the flat box reservoir is filled.
After making the proper adjustments, the professional can use the tool. For a flawless application, they must make slow, steady movements. The aim is precision rather than speed.
Once the compound has been applied, the finish is completed by running a trowel or jointing knife over the fresh compound to smooth out any remaining imperfections. After drying – be sure to follow the manufacturer’s recommended drying time – you can finish by sanding the surface.
Flat box: pitfalls to avoid, tips to know
Even though the flat box is easier to use than bulky devices like the bazooka, mistakes can still be made.
The first is incorrect adjustment before application. The flat box must be properly set up before use; a correct adjustment prevents digging in too much when depositing compound and thus ensures a smooth, even finish.
Attention should also be paid to the amount of compound laid down, which must be even and consistent. This sometimes requires a little practice, but above all regular, precise movements.
The advantage of the flat box is that, in addition to boosting productivity and quality, it lets you work at ground level. It is also easy to clean – which is a plus, because proper maintenance and cleaning are essential for continuing to use the tool in good condition.