Does Masonry Paint Need a Primer? (Explained)

Priming before applying paint helps the paint adhere better. But what if you are working on masonry? Does masonry paint need a primer? Here is the answer to that.

Yes, masonry paints need a primer or undercoat before they are applied. This is because masonry surfaces have increased moisture retention. If you apply masonry paint without sealing or priming the stone surface first, the paint will not dry well.

Also, masonry is usually rough and sometimes riddled with cracks and holes. So if the masonry paint is applied directly to the masonry, the finish will not be smooth.

But there is more to know about applying masonry paint and this post digs right into the topic.

Let’s dive in.

Can You Paint Straight Onto Masonry?

You shouldn’t paint straight onto masonry. This is because masonry surfaces are not ideal for paint application. If you paint straight onto masonry either with regular paint or masonry paint, the paint will not stick.

Also, the finish will be filled with paint pimples and slits. Eventually, the whole finish will peel off the masonry.

Masonry is one of the toughest finishes in building and construction. The finish is made from a combination of materials like rocks, sand, cement, and the likes. All of these materials are mixed to produce a finish with improved moisture retention. This means that masonry does well to hide and retain water.

So if you apply paint directly onto masonry without priming the masonry first, the paint coating will be severely affected by moisture. The moisture content of the masonry surfaces will prevent the paint coating from having good adhesion to the masonry.

Also, masonry is usually rough. Old masonry surfaces especially are usually riddled with cracks, holes, and sometimes nail holes. If the paint is applied over such a surface, the finish will be very rough and bumpy. So it’s not advised to paint directly on masonry.

Does Masonry Paint Need an Undercoat?

Masonry paint needs an undercoat or primer to adhere properly and provide a fine finish. Without an undercoat, masonry paint when dry will have bumps and eventually peel off.

The undercoat or primer helps to seal the masonry to prevent moisture from affecting the masonry paint coating. It helps to provide a smooth surface that the masonry paint can be applied on.

Also, masonry paint needs an undercoat because masonry is a bit porous due to hairline cracks. This means that the masonry surface will require more paint coatings to be fully covered. But an undercoat seals the masonry preventing paint wastage.

When it comes to painting masonry or stone surfaces, an undercoat is always necessary before applying the paint. This is because masonry paint will not stick without an undercoat. For paint to stick, the material to be painted shouldn’t be rough.

However, masonry as explained earlier is usually rough. The rough texture of masonry will not allow masonry paint to bond. It will also produce a rough finish when the paint dries. The undercoat helps to cover this rough surface and when dry, will provide a smooth surface for the masonry paint to bond to.

The masonry material after a while will also have tiny holes and hairline cracks. Hairline cracks are those thin lines you see on old masonry surfaces. These lines as small as they are suck paint. Without an undercoat, you’ll end up using way more paint on the masonry.

However, an undercoat helps to seal these cracks and holes so you use as little paint as possible. This means you can cover more areas and have more coatings.

So unless you want a bad finish with way more paint used; yes. Masonry paint needs an undercoat.

Another thing to know is if masonry paints need a topcoat. Let’s find out.

Does Masonry Paint Need a Top Coat?

Masonry paints don’t need a top coat or sealant. This is because masonry paints are specially designed with solvents to be tough given the type of material and environment they are used in.

Also, masonry paints when dry have a very thick texture. The thickness of the finish is not only durable enough without a top coat but it also prevents top coats and sealants from adhering well. However, this goes for solvent-based masonry paints.

Acrylic and latex masonry paints are usually sealed with a top coat to prevent the colors from fading due to the effects of the weather. This is because these masonry paints are water-based and not as durable as solvent or chemical-based masonry paints.

Masonry paint is commonly used on not just masonry but concrete, brick, stucco, and cinder blocks. Many of these materials are very rough. Asides from that, these materials are mainly used for building exteriors. It’s very common to see masonry fences, concrete walls, and the likes.

As such, the paints used on these rough exterior surfaces are designed to be very strong and durable. Durable enough to last several years without a top coat.

But this is usually for solvent-based masonry paints. Solvent-based masonry paints have additives and resins that make the paint coating extra tough and weather friendly. So no top coat is needed.

Acrylic and latex masonry paints on the other hand usually require a sealant like wax. This is because these paints are designed to be colorful and attractive. As such, they are mostly designed with extra pigments and are water-based.

The water-based nature makes this masonry paint less durable than the solvent-based versions. So you’ll need a sealant for acrylic and latex masonry paint.

Does Sandtex Masonry Paint Need a Primer?

Sandtex masonry paint will need a primer before it is applied especially on very rough masonry.

Sandtex is a leading paint type, especially for masonry. The paint uses micro-seal technology to provide unmatched results on masonry even without using a primer first. However, you can only get a smooth Sandtex finish on properly prepped masonry.

If the masonry is rough, you’ll need not just a primer but also the Sandtex ready mixed masonry filler. The filler is used to repair masonry before the masonry paint is used. The Sandtex masonry filler can also be used as a primer.

Sandtex masonry finish is one of the best even without a primer. This is why most DIYers feel the paint doesn’t need a primer. Though Sandtex masonry paint will still provide a good finish without a primer, the finish can only be gotten on well-sanded masonry.

If the masonry is smooth, then you can apply the Sandtex masonry paint without using a primer first. However, if the masonry is rough or riddled with hairline cracks, it’s advised to use a primer or the Sandtex masonry filler first. The primer will seal the masonry and provide a smooth surface for the paint to adhere to.

You can also know if you need a primer by trying the Sandtex tester pots. The tester pots are small paint cans that have different paint types for masonry. You can try the paint types on masonry without a primer and check out each finish.

What Type of Primer Do You Need For Masonry Paint?

You need an epoxy concrete primer for masonry paint. Epoxy primers will absorb and grip the masonry creating a firm and smooth surface for the masonry paint. Epoxy primers also treat the masonry material by sealing and covering cracks and holes that can suck paint.

Also, epoxy primer is ideal because oil-based primers are better than water-based primers for concrete. This is because oil-based primers like epoxy have chemicals and additives that help the primer coating bond well to masonry.

When you want to prime masonry for paint application, you need a primer designed to seal and repair tough surfaces like concrete. You also need a primer that has enough resins and additives to adhere to the porous texture of masonry.

Oil-based primers like enamel sometimes have resins that react and grip the masonry to provide a strong and smooth undercoat.

This is why latex primers aren’t ideal for masonry. Latex primers are water-based which means they don’t have chemicals or resins that improve paint bonding. This doesn’t mean you can’t use latex primer for masonry. It just wouldn’t be as strong as oil or solvent-based primers.

What Happens If You Don’t Prime Before Painting Masonry?

If you don’t prime before painting masonry, the paint coating(s) will peel off and tear. This is because the rough texture of the masonry material will affect the curing process of the paint. The paint particles will not bond together while curing.

Instead, the paint particles will be separated and they will cure in different segments. The paint separation occurs due to the presence of edges and bumps in the masonry.

These edges and bumps poke out of the paint coating after it is applied. Over time, the finish will appear torn. This will create gaps in the paint coating that will make the paint more susceptible to moisture and friction. The finish will eventually start to peel off the masonry and fall.

Sure, you can apply more coats of masonry paint to seal these edges but doing this will just result in paint wastage and uneven application. Also, the paint coating will not dry evenly and there will be color variations. The only way out of this is to prime the masonry before the paint is applied. So how do you do that? Let’s take a closer look.

Final Words

Overall, you need to prime before applying masonry paint. This helps the finish in so many ways and it also makes it easier to apply the masonry paint.

Also, you should remember to sand the masonry before applying the paint. Sanding and priming will guarantee a perfect finish.

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