Drywall must be primed before it can be painted to ensure that the paint stays on and isn't affected by temperature changes in the room or environment. To prime your drywall, you need to clean it first by sanding it, vacuuming it, and rubbing it down with a black cloth to ensure that all dust is gone.
With that being said, the only real prep work that you need to do before priming the wall, is just sanding down the wall with some fine sandpaper. Anything above 200 grit should be fine. Make sure to wipe down all the dust with a moist towel after!
Whether you're priming a porous substance such as wood or a smooth substance such as metal, you need to sand the substance beforehand. Sanding a surface removes the top glossy layer, allowing the substance to receive the primer.
To prime your drywall, you need to clean it first by sanding it, vacuuming it, and rubbing it down with a black cloth to ensure that all dust is gone. Once that's complete, you can begin applying primer to your drywall so that you can ensure that your paint stays in place for a long time.
If you look online, which I did, there are 2 methods to removing drywall dust. 1. Brushing it off the wall and vacuuming (repeated 3x) or 2. Use a barely damp rag to wipe it down.
Preparing wood for a project is a multi-step process. After sanding a piece of wood, you'll need to clean it before adding a stain or paint. You can use a variety of tools and techniques to remove sanding dust from your wooden surface.
After sanding drywall, you need to vacuum again and again till the dust has been completely removed. If not, the dust will sit on your freshly painted walls. While sanding, you might see some imperfections which must be sealed.
A minimum of two coats of PVA primer is necessary when painting new drywall in order to prevent the paint finish from looking splotchy and uneven after drying. New drywall is like a sponge, and it's better to let it soak up inexpensive primer than expensive paint.
Back-rolling is typically most impactful when applying the primer for the interior walls of a home or a new construction build. While the primer is the coat that bonds with the substrate initially, airless spraying itself does not penetrate or enhance adhesion.
Drywall mud can take as long as 24 hours to dry for thick applications. The 24-hour drying time recommendation can be applied to nearly all factors. Some manufacturers will bring down that number to 12 hours if a few shortcuts are applied to help speed up drying time without affecting the finished product.
It's easiest to remove drywall dust when lightly wetted, but because drywall is faced with paper that does not react well to water, it's best to use dry methods to clean before wet. Using a hand brush, sweep dust from the drywall moving top-to-bottom.
It is always important to properly prepare the surface before applying primer. At the very least, the surface has to be clean and free of dust, dirt and debris. Failing to clean the surface prior to applying primer may compromise the adhesion of the primer to the surface – which could lead to peeling and blistering.
The Golden Rule of Sanding
The golden rule for choosing your sequence is to never skip more than 1 grit. For example, if you start with P80, and need to finish at P240, rather than using every grit from P80 – P220, you can do P80 – P120 – P180 – P240.
Wood dust becomes a potential health problem when wood particles from processes such as sanding and cutting become airborne. Breathing these particles may cause allergic respiratory symptoms, mucosal and non-allergic respiratory symptoms, and cancer.
Over time, breathing the dust from drywall joint compounds may cause persistent throat and airway irritation, coughing, phlegm production, and breathing difficulties similar to asthma. Smokers or workers with sinus or respiratory conditions may risk even worse health problems.
Many shop vacs on the market can handle drywall dust, but that may not be true for all shop vacs. That is why it is important to make sure a vacuum offers all of what makes a good shop vac for drywall dust.
Clean walls after sanding
If you've just sanded your wall, perhaps after applying a dollop of filler to a crack, then you'll need to clean it before going any further. This will prevent that stray plaster dust from nestling into the carpet or getting mixed up with your paint.