How to Apply Mist Coating On a New Plaster?

Painting porous surfaces like wood, particleboard, concrete, new plaster, etc., is sometimes tricky due to how much paint they can soak.

You just bought a new 5-gallon paint tub, started applying it on the surface, and found it disappeared in the middle of the project without covering the entire surface.

If you have ever had this problem, a mist coat is the answer.

What’s a mist coat? what it does, and why it’s so important? Let’s find out in this today’s article.

What is a Mist Coat?

A mist coat is a very thin coat of paint used to seal the surface and prevent it from soaking up too much paint. This allows you to use less paint overall and still get even coverage.

Mist coat is typically made of watered-down paint, which must be applied on newly plastered walls, raw wooden beams, foundations, etc., for sealing and preventing peeling of the paint later in the future.

Once the surface has been properly sealed, less paint will be soaked in successive coats.

However, the paint should be prepared by watering down in the proper ratio to get a practical mist coat without worrying about enough absorption and cracks.

How to Prepare a Mist Coat?

Correctly making your “mist coat” is crucial for the success of the paint job.

If you make it too thick, it’ll take forever to dry and will not get absorbed as it should; too thin might not do the job at all.

Generally, the water-to-paint ratio for a mist coat should be 1:1; if you use one gallon of paint, you should add one part of water to it to make a mist coat.

That said, you do not have to be precise over here, as it can be customized according to the surface you are coating.

I typically use 60% paint to 40% water for wooden boards like MDF. But for concrete and fresh plaster mist coats, 50% paint to 50% water is what I use.

Here are the detailed steps and instructions you can follow to prepare your mist coat…

Step 1- Get the Paint for the Mist Coat

Choose a water-based emulsion paint that does not contain vinyl. For a mist coat, it should contain acrylic as the main ingredient.

For the color, you should select the one that matches your top coat best. If your top coat color, for example, is white, choose an emulsion paint that is also white.

The closer the hue of white you choose to the top coat, the better, because it will allow you to get the desired finish by applying only one layer of top coat.

To make matching them simpler, get the top coat and emulsion paint from the same manufacturer or brand.

Step 2- Use a 1:1 Ratio of Paint and Water for Your Mist Coat

To make 50/50 paint, combine one part water and one part paint in a plastic bucket.

Use a paint mixer to blend the two together until the mixture appears watery and runny.

This ratio of liquid to pigment will guarantee that the plaster is sealed well as the paint absorbs into it quickly.

I recommend mixing the mist coat just before you intend to paint since this will prevent it from sitting too long.

Also, I said before you need not be too exact with the ratios as they can be customized according to the surface.

For example, if you want a slightly thicker mist coat for better absorption on a very porous surface like new plaster, you might want to use two parts of water for one part of the paint. And that should do fine.

Step 3- Buy a Pre-Made Mist Coat Online or at Your Local Hardware Store

Many pre-made mist coat products are available for purchase if you do not want to make your own. Just be sure that the product is water-based and matches the color of your top coat.

You can also buy plaster paints, which can be used as mist coats. These will speed up the drying process and are made explicitly for application over plaster walls.

If you need help choosing a paint mist coat brand or color, you can always contact the manufacturer or speak with a representative at your local hardware store for better guidance.

How to Apply the Mist Coating Correctly?

Applying a mist coat on a new plaster is pretty straightforward and does not need any professional skills. Just follow the steps below, and you’ll be good to go…

Step 1- Prepare the Area

The mist coat can be messy to apply since the paint will be very wet and runny. So, lay down canvas tarps or paint sheets on the floor in the room for protection.

Remove any furniture in the room so that it won’t get covered with runny paint, or you can cover the furniture with a tarp or sheet.

Also, consider wearing old clothes you don’t mind getting dirty, like an old shirt and jeans for painting.

Step 2- Prepare the Surface for the Mist Coating

This includes cleaning the surface and checking for any holes, gaps, and damages.

If you plan to put the mist coat on wood or ply boards, check the edges and seal them properly with a wood filler.

For plastered walls, fill them with joint compound, and for any holes in the wall, use a patching compound.

Preparing the surface also means getting it thoroughly dried. Do not use the mist coat on wet plaster, as this will harm the plaster.

Plaster takes approximately one to two days to dry. To ensure no damp regions, touch the plaster with your hand and confirm before you proceed. If it still feels damp, give it some more time to dry.

Step 3- Pour the mixture into a Paint Tray and Load the Roller

Get your paint roller and fit it with a clean microfiber roller sleeve. The sleeve should be of the right size for the paint roller so that it can cover a broad area with one pass.

Pour the mist coat mixture into a paint tray and then dip the roller sleeve into the mixture.

Make sure you don’t fill the tray to the brim because you don’t want the paint to spill over when you roll it.

Roll off any excess paint on the sides of the tray to avoid dripping. The roller should have an even layer of paint and be wet enough to spread the paint onto the plastered wall but not too wet to drip.

Step 4- Begin Applying Mist Coat from the Bottom and Work Your Way Top

Paint the wall in smooth, upward strokes. Begin in the lower bottom corner of the room and work your way up.

If a mist coat doesn’t adequately cover an area, you may apply one more coat to it.

The aim is for the wall to be painted with an even layer of the mist coat to ensure that the plaster is adequately sealed.

Overlapping paint won’t seal the plaster well; just cover any gaps with paint and proceed to the next step.

Step 5- Using a Paintbrush, Seal all the Corners in the Room and Missed Spots

Any locations you can’t reach with the roller, such as the edges of the room, corners, or just above the baseboards, may be painted with a tiny paintbrush.

Use a small paint brush dipped in a mist coat to cover all these difficult-to-reach places and check for any missed spots.

Use a paintbrush to touch up and mist-coat any areas that seem to have been missed with the roller.

Tips for Applying the Top Coat Over Mist Mist-Coated Surface

The top coat should only be applied once the mist coat is dried correctly. So, do not touch or go near the mist coat for 24 hours till it dries.

Leave the windows open in the room to help with ventilation. You can also use small fans to circulate air and speed up drying time, but make sure they aren’t left in one spot, as that will cause uneven drying.

If you plan on leaving the windows open, check beforehand that there is no chance of rain or other wet weather conditions that can bring moisture indoors.

After the mist coat has dried and you have confirmed the dry-to-the-touch surface, apply two layers of your selected top coat using a clean roller in an upward motion.

Use a small paintbrush to reach any problematic spots, like above baseboards or in corners.

Let the first layer dry overnight before applying the second (and third, if desired, for extra color strength).

The Bottom Line

A mist coat is a crucial step in painting because it provides a layer for the paint to grip on, prevents the paint from sinking into the plaster, and creates an even surface for painting.

It is essential to take the time to do it right so that your paint job will be beautiful and last a long time.

So, ensure you learn the techniques beforehand and use the right paint type for a mist coat for a successful paint job.