Brick mortar takes around 48 hours to dry to a point known as touch dry. However, brick mortar needs 28 days to reach its highest level of curing. Brick mortar drying time also depends on the type of mortar being used, weather conditions, airflow, and the thickness of the applied mortar. 

Questions like mortar drying time, color changes in mortar, and the different types of mortar are all answers we at Lontto will be answering. These facts will help you take the right steps when applying mortar to your building project.

Key Takeaways

  • Mortar becomes touch dry in 48 hours but needs 28 days to fully cure. Misting during the 7 days helps prevent cracks and ensures strength.
  • From ultra-strong Type M (2,500+ psi) for foundations to delicate Type K (75 psi) for historic restorations, each mortar type suits a specific purpose. 
  • Mild conditions (50 to 70 °F, 40 to 60% humidity) speed up drying, whereas heat, cold, or moisture can slow curing or cause cracks.
  • Mortar lightens as it dries, but factors like weather and mix consistency can affect the final hue. Test small batches and wait 28 days for the true color.

What are the Different Kinds of Mortar and Their Drying Times? 

Different kinds of mortar include Type M, Type O, Type N, Type K, and Type S (M.O.N.K.S. makes this easy to remember). Each mortar has a different psi, but drying times for all mortar types are generally the same (28 days to fully cure). 

how long does brick mortar take to dry

how long does brick mortar take to dry (mobile)

Mortar Type Compressive Strength (PSI) Best Use Cases Factors Affecting Drying Drying & Curing Time
M 2,500+ – Foundations

– Retaining walls

– Driveways

 – Temperature

– Moisture

– Thickness

– Ventilation

 Touch Dry: 12 to 24 hrs

Full Cure: ≈ 28 days
S 1,800+ – Exterior walls

– Patios

– Below-Grade Projects

 – Temperature

– Humidity 

– Air Exposure

 Touch Dry: 12 to 24 hrs

Full Cure: ≈ 28 days
N 750+ – Chimneys 

– Exterior Walls

– General Use

 – Weather 

– Joint Thickness

– Water Content

 Touch Dry: 12 to 24 hrs

Full Cure: ≈ 28 days
O 350+ – Interior Walls

– Non-Load-Bearing Repairs

 – Temperature

– Airflow 

– Moisture Retention

 Touch Dry: 12 to 24 hrs

Full Cure: ≈ 28 days
K 75+ – Historical Restorations 

– Soft Stonework

 – Low Strength

– Requires Slow Drying

 Touch Dry: 12 to 24 hrs

Full Cure: ≈ 28 days

When using the above table, it’s important to remember that:

  • Touch dry means that the mortar is dry and reasonably firm to the touch but not fully hardened.
  • When the mortar is fully cured, it reaches its maximum strength.
  • Environmental conditions must be balanced because high humidity slows down the drying process. On the other hand, extreme heat causes premature cracking in the mortar.
  • Keep brick mortar slightly moist for the first 48 hours to prevent shrinkage and cracks.

Type M: The Strongest PSI Mortar

Type M mortar is the hardest and strongest of all mortar types (over 2,500 psi). It’s often used in load-bearing walls, building foundations, and driveway paving. This type of mortar should be misted 3 times a day for the first 7 days after its application because it’s prone to cracking in overly dry conditions. 

Type S: Exterior Mortar

Type S brick mortar is typically used on exterior builds to withstand harsh weather conditions after it has fully cured (28 days). Thanks to its 1,800 psi, it can endure heavy weight, damp environments, and seismic force. Mixing Type S mortar correctly is important for it to maintain its durable properties, and misting for the first 7 days is also beneficial.  

Type N: General Use Mortar

Type N brick mortar is what most DIY enthusiasts use to renovate their homes. It has a medium psi of 750, making it perfect for fixing up walls, chimney repairs, and ground-level brick layering. It’s generally fine to use for most light construction work, but you should not use it for heavy load-bearing walls. 

Type O: Decorative and Interior Mortar

Type O mortar is what you would typically use for the inside of your house. It only has a psi of 350, so the cured result of Type O mortar can be crumbly. This type of mortar is usually painted over after its application because sealing it is essential for preserving its shape.

Type K: Restoration Mortar

Type K mortar is almost exclusively used for the restoration of non-load-bearing structures. It’s not commonly used for any type of light or heavy construction because it takes a long time to cure, and remains soft even after its integrity is established. With a low psi of only 70, Type K mortar is good for preserving historic masonry. 

Does Mortar Change Color When it Dries?

Yes, mortar changes color when it dries. It goes lighter the dryer it gets, but it can also be affected by weather conditions, mixing consistency, and the amount of salt content in the atmosphere. If the final color of cured mortar is a concern, you should test a small batch first and give it 28 days to fully cure. 

What’s the Difference Between Touch Dry and Fully Cured Mortar?

The main difference between touch-dry and fully cured brick mortar is the time it takes to reach those stages. Within 48 hours, your mortar will be touch dry and have some integrity. But it becomes more solidified as time goes by and only becomes “fully cured” after 28 days, regardless of the type of mortar. 

Mortar PSI: Why is it Important?

Mortar psi is important because using the wrong psi mortar will not have enough hardness to withstand load-bearing or harsh weather conditions. You should always use higher psi mortar for heavy construction, while lower psi is fine to use indoors or for masonry restoration purposes. 

The team at Lontto has over 30 years of experience in brick-making, so contact us for all of your brick-drying, brick-making, and machinery questions. We’re always happy to help and provide guidance where we can. We offer a wide range of high-quality brick-making machines, with training and installation included! Contact us today! 

How Long Does Brick Mortar Take to Dry? | FAQs

What are the ideal weather conditions for drying mortar?

The ideal weather conditions for drying mortar are:

  • Temperatures of between 50 and 70 °F (≈ 10 to 21 °C)
  • Humidity of 40 to 60%
  • Low wind conditions of 10 mph or less
  • No rain for the first 48 hours
  • Partial shade from the sun if possible

What makes mortar dry faster?

Mortar dries faster when less water is used to mix it. However, most mortar types dry at the same pace: 48 hours until touch dry, and 28 days until fully cured. Mortar also dries faster when weather conditions are optimal, such as mid-temperature, low wind conditions, medium humidity, and no rain. 

Should I spray mortar with water while it dries?

Yes, you should spray mortar with water while it dries to prevent cracking; this is called misting. You can do this after 4 to 8 hours of applying the mortar — a light mist or water is sufficient. You can mist your mortar 2 to 3 times a day for the first 7 days.

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Author: Chao Zhang

I am Chao Zhang, I have been working in the brick making industry for over 10 years. I have a deep understanding and research on various models of block making machines, especially automatic brick machines, concrete block machines, compressed earth block machines, clay brick machines, cement brick machines. I have a special understanding of this industry. I can help my clients choose the suitable brick machine and assist them in designing and building a brick production factory. If you want to know everything about brick making machines, please contact me. I am happy to help you.