Why Use Priming Slurry? (Pros & Cons) - Pavingsuperstore.co.uk

When it comes to preparing surfaces for various paving projects, priming slurry has become a popular choice among professionals and DIY enthusiasts alike. Priming slurry is a thin, cementitious material that is applied to a substrate before laying your paving slabs and serves several purposes, but like any construction material, it has its advantages and disadvantages. In this article, we'll delve into when priming slurry is needed and the pros and cons of using priming slurry to help you make an informed decision for your next project.

What is Priming Slurry?

Priming slurry is a thin, cementitious material used as a preparatory layer before applying paving slabs. It's sometimes known as a bond bridge, slurry primer and simply a primer. 

Adhesion For Non-Porous Stone, such as Porcelain and Low Porosity Stone such as Granite and Slate:

Its main purpose is to enhance the adhesion between the wet mortar bed and the paving, providing a strong bond for the overall construction. Priming slurry is particularly essential for certain situations, such as when working with non-porous and low porosity stones like porcelain, slate and granite. These materials have inherently smooth, non porous surfaces that can pose adhesion challenges for paving projects. By using priming slurry, the adhesion between the non-porous/ low-porosity stone and the mortar bed is significantly improved, ensuring a durable and long-lasting finish.

Mortar Bed Stain Prevention For Porous Stone, such as Sandstone, Limestone and Concrete:

With porous stone types, the process of the paving adhering to the mortar bed occurs by the stone drawing up the mortar into the tiny capilliaries and forming a bond, therefore priming slurry is not required for adhesion purposes. However, in drawing up moisture from the mortar (especially when a very wet mix has been used), occasionally the colour of the mortar can appear on the surface of the paving leaving patchy discoloured markings. Priming slurry is indispensable for dealing with 'through bed staining' on porous stone types. It acts as a moisture barrier, reducing the stone's porosity and preventing the bedding mortar from staining or drawing through to the surface of the stone. Whilst through bed staining is not apparent in many installations, it is often more noticable on stones with a light coloured or plain finish, for example sawn sandstone and is recommended in these applications. 

In both cases, using priming slurry ensures a solid foundation, better adhesion, and a visually appealing end result for a variety of construction projects.


How to Use Priming Slurry

Using priming slurry is a straightforward process, but it requires attention to detail and proper preparation to ensure its effectiveness. Below, we outline the step-by-step procedure for applying priming slurry:

Step 1: Surface Preparation Before applying the priming slurry, prepare your wet mortar bed. Slurry primer is deigned to work in conjunction with this as part of the process for installation. 

Step 2: Mixing the Priming Slurry Carefully follow the manufacturer's instructions for mixing the priming slurry. Usually, it involves adding a specific amount of clean water to the dry slurry mix and thoroughly blending the two components. Use a mixing paddle attached to a drill for consistent results. Avoid overmixing to prevent air bubbles from forming in the slurry.

Step 3: Application Using a brush or roller, apply the priming slurry thinly and evenly to the underside of the paving slab you ar about to lay. Work in small sections to ensure uniform coverage. The aim is to create a thin and uniform layer of priming slurry on the underside of the paving.

Step 4: Lay the Paving After applying the priming slurry, place the paving slab onto the mortar bed and press into place. 

Step 5: Cleaning Up Immediately remove and slurry primer from uppermost face of the paving slabs as it will quickly dry and mark the paving. Also note that the slurry mix can harden and become difficult to remove if left to dry on tools so be sure to clean these off before it has time to dry.

By following these steps and adhering to the manufacturer's guidelines, you can successfully use priming slurry to enhance the adhesion and through bed stain prevention of your paving project, whether it involves non-porous stones like porcelain and granite or porous stone types susceptible to through bed staining. Remember that each project may have specific requirements, so always adjust your approach accordingly and seek professional advice if needed.

What are the Pros and Cons of Using Priming Slurry?

Like any construction material, priming slurry comes with its own set of advantages and disadvantages that are worth considering before implementation. In this section, we will explore the pros and cons of using priming slurry, shedding light on its benefits and potential drawbacks for various applications.


  1. Improved Adhesion: One of the primary benefits of using priming slurry is that it significantly enhances the adhesion between the mortar bed and the paving. It creates a strong bond that reduces the risk of paving slabs detaching from their mortar bed. This is imperative to non porous paving such as porcelain and also beneficial to low porosity paving such as slate and granite. 

  2. Reduced Water Absorption: Priming slurry acts as a moisture barrier, reducing the porosity of the paving. This results in less water from the mortar bed being absorbed into the stone and potentially staining the surface of the paving, which is especially beneficial when applying to porous surfaces, such as sandstone, limestone and concrete paving. 

  3. Cost-Effectiveness: Priming slurry is relatively inexpensive compared to other construction materials. Considering the benefits it provides in terms of enhanced adhesion and reduced water absorption, using priming slurry can save costs by minimising the risk of potential rework due to adhesion failure or surface imperfections.
  4. Versatile: Priming slurry can be used to help bond difficult to adhere items such as wall coping, pier caps and step treads in addition to reinstalling individial paving slabs that may have worked loose from a previous installation.


  1. Additional Step: Introducing priming slurry into the construction process requires an extra step, which can be seen as a disadvantage for some projects where time is of the essence. However, this extra step is often offset by the time saved in the long run due to better adhesion.

  2. Skill and Experience Required: Proper application of priming slurry demands a certain level of skill and experience to ensure its effectiveness. Inexperienced individuals may struggle to prevent the slurry primer from running onto the surface of the stone, leading to markings on the uppermost face. It's crucial to follow the manufacturer's guidelines and best practices for application.

  3. Health and Safety Precautions: As with any construction material, using priming slurry requires appropriate safety measures. The dust generated during its preparation and application can be harmful if inhaled, so proper respiratory protection and ventilation are crucial.

Pavetuf Priming Slurry


In conclusion, priming slurry offers numerous advantages, such as improved adhesion, reduced water absorption, and a versatile adhesive suitable for many other landscaping projects. It is cost-effective and can save time in the overall construction process. However, it does require careful application and consideration of compatibility issues. By weighing the pros and cons, you can decide whether using priming slurry is the right choice for your specific construction or renovation project. Always follow the manufacturer's instructions and seek professional advice if needed to ensure successful results.